[R] Set number of threads in demos and tests. (#9591)

- Restrict the number of threads in IO.
- Specify the number of threads in demos and tests.
- Add helper scripts for checks.

R-package/.Rbuildignore

@@ -4,3 +4,5 @@
 ^.*\.Rproj$
 ^\.Rproj\.user$
 README.md
+^doc$
+^Meta$

R-package/R/callbacks.R

@@ -557,14 +557,18 @@ cb.cv.predict <- function(save_models = FALSE) {
 #'
 #' @examples
 #' #### Binary classification:
-#' #
+#'
+#' ## Keep the number of threads to 1 for examples
+#' nthread <- 1
+#' data.table::setDTthreads(nthread)
+#'
 #' # In the iris dataset, it is hard to linearly separate Versicolor class from the rest
 #' # without considering the 2nd order interactions:
 #' x <- model.matrix(Species ~ .^2, iris)[,-1]
 #' colnames(x)
-#' dtrain <- xgb.DMatrix(scale(x), label = 1*(iris$Species == "versicolor"), nthread = 2)
+#' dtrain <- xgb.DMatrix(scale(x), label = 1*(iris$Species == "versicolor"), nthread = nthread)
 #' param <- list(booster = "gblinear", objective = "reg:logistic", eval_metric = "auc",
-#'               lambda = 0.0003, alpha = 0.0003, nthread = 2)
+#'               lambda = 0.0003, alpha = 0.0003, nthread = nthread)
 #' # For 'shotgun', which is a default linear updater, using high eta values may result in
 #' # unstable behaviour in some datasets. With this simple dataset, however, the high learning
 #' # rate does not break the convergence, but allows us to illustrate the typical pattern of
@@ -594,9 +598,9 @@ cb.cv.predict <- function(save_models = FALSE) {
 #'
 #' #### Multiclass classification:
 #' #
-#' dtrain <- xgb.DMatrix(scale(x), label = as.numeric(iris$Species) - 1, nthread = 1)
+#' dtrain <- xgb.DMatrix(scale(x), label = as.numeric(iris$Species) - 1, nthread = nthread)
 #' param <- list(booster = "gblinear", objective = "multi:softprob", num_class = 3,
-#'               lambda = 0.0003, alpha = 0.0003, nthread = 1)
+#'               lambda = 0.0003, alpha = 0.0003, nthread = nthread)
 #' # For the default linear updater 'shotgun' it sometimes is helpful
 #' # to use smaller eta to reduce instability
 #' bst <- xgb.train(param, dtrain, list(tr=dtrain), nrounds = 50, eta = 0.5,

R-package/R/xgb.Booster.R

@@ -267,11 +267,16 @@ xgb.Booster.complete <- function(object, saveraw = TRUE) {
 #'
 #' data(agaricus.train, package='xgboost')
 #' data(agaricus.test, package='xgboost')
+#'
+#' ## Keep the number of threads to 2 for examples
+#' nthread <- 2
+#' data.table::setDTthreads(nthread)
+#'
 #' train <- agaricus.train
 #' test <- agaricus.test
 #'
 #' bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
-#'                eta = 0.5, nthread = 2, nrounds = 5, objective = "binary:logistic")
+#'                eta = 0.5, nthread = nthread, nrounds = 5, objective = "binary:logistic")
 #' # use all trees by default
 #' pred <- predict(bst, test$data)
 #' # use only the 1st tree
@@ -337,8 +342,14 @@ predict.xgb.Booster <- function(object, newdata, missing = NA, outputmargin = FA
                                 reshape = FALSE, training = FALSE, iterationrange = NULL, strict_shape = FALSE, ...) {
   object <- xgb.Booster.complete(object, saveraw = FALSE)
 
-  if (!inherits(newdata, "xgb.DMatrix"))
+  if (!inherits(newdata, "xgb.DMatrix")) {
-    newdata <- xgb.DMatrix(newdata, missing = missing, nthread = NVL(object$params[["nthread"]], -1))
+    config <- jsonlite::fromJSON(xgb.config(object))
+    nthread <- strtoi(config$learner$generic_param$nthread)
+    newdata <- xgb.DMatrix(
+      newdata,
+      missing = missing, nthread = NVL(nthread, -1)
+    )
+  }
   if (!is.null(object[["feature_names"]]) &&
       !is.null(colnames(newdata)) &&
       !identical(object[["feature_names"]], colnames(newdata)))
@@ -628,10 +639,15 @@ xgb.attributes <- function(object) {
 #'
 #' @examples
 #' data(agaricus.train, package='xgboost')
+#' ## Keep the number of threads to 1 for examples
+#' nthread <- 1
+#' data.table::setDTthreads(nthread)
 #' train <- agaricus.train
 #'
-#' bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+#' bst <- xgboost(
-#'                eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic")
+#'   data = train$data, label = train$label, max_depth = 2,
+#'   eta = 1, nthread = nthread, nrounds = 2, objective = "binary:logistic"
+#' )
 #' config <- xgb.config(bst)
 #'
 #' @rdname xgb.config

R-package/R/xgb.DMatrix.R

@@ -18,7 +18,12 @@
 #'
 #' @examples
 #' data(agaricus.train, package='xgboost')
-#' dtrain <- with(agaricus.train, xgb.DMatrix(data, label = label, nthread = 2))
+#' ## Keep the number of threads to 1 for examples
+#' nthread <- 1
+#' data.table::setDTthreads(nthread)
+#' dtrain <- with(
+#'   agaricus.train, xgb.DMatrix(data, label = label, nthread = nthread)
+#' )
 #' xgb.DMatrix.save(dtrain, 'xgb.DMatrix.data')
 #' dtrain <- xgb.DMatrix('xgb.DMatrix.data')
 #' if (file.exists('xgb.DMatrix.data')) file.remove('xgb.DMatrix.data')

R-package/R/xgb.load.R

@@ -22,14 +22,23 @@
 #' @examples
 #' data(agaricus.train, package='xgboost')
 #' data(agaricus.test, package='xgboost')
+#'
+#' ## Keep the number of threads to 1 for examples
+#' nthread <- 1
+#' data.table::setDTthreads(nthread)
+#'
 #' train <- agaricus.train
 #' test <- agaricus.test
-#' bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+#' bst <- xgboost(
-#'                eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
+#'   data = train$data, label = train$label, max_depth = 2, eta = 1,
+#'   nthread = nthread,
+#'   nrounds = 2,
+#'   objective = "binary:logistic"
+#' )
+#'
 #' xgb.save(bst, 'xgb.model')
 #' bst <- xgb.load('xgb.model')
 #' if (file.exists('xgb.model')) file.remove('xgb.model')
-#' pred <- predict(bst, test$data)
 #' @export
 xgb.load <- function(modelfile) {
   if (is.null(modelfile))

R-package/R/xgb.model.dt.tree.R

@@ -46,9 +46,12 @@
 #' # Basic use:
 #'
 #' data(agaricus.train, package='xgboost')
+#' ## Keep the number of threads to 1 for examples
+#' nthread <- 1
+#' data.table::setDTthreads(nthread)
 #'
 #' bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 2,
-#'                eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
+#'                eta = 1, nthread = nthread, nrounds = 2,objective = "binary:logistic")
 #'
 #' (dt <- xgb.model.dt.tree(colnames(agaricus.train$data), bst))
 #'

R-package/R/xgb.plot.deepness.R

@@ -45,10 +45,13 @@
 #' @examples
 #'
 #' data(agaricus.train, package='xgboost')
+#' ## Keep the number of threads to 2 for examples
+#' nthread <- 2
+#' data.table::setDTthreads(nthread)
 #'
-#' # Change max_depth to a higher number to get a more significant result
+#' ## Change max_depth to a higher number to get a more significant result
 #' bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 6,
-#'                eta = 0.1, nthread = 2, nrounds = 50, objective = "binary:logistic",
+#'                eta = 0.1, nthread = nthread, nrounds = 50, objective = "binary:logistic",
 #'                subsample = 0.5, min_child_weight = 2)
 #'
 #' xgb.plot.deepness(bst)

R-package/R/xgb.plot.importance.R

@@ -45,9 +45,14 @@
 #'
 #' @examples
 #' data(agaricus.train)
+#' ## Keep the number of threads to 2 for examples
+#' nthread <- 2
+#' data.table::setDTthreads(nthread)
 #'
-#' bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 3,
+#' bst <- xgboost(
-#'                eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic")
+#'   data = agaricus.train$data, label = agaricus.train$label, max_depth = 3,
+#'   eta = 1, nthread = nthread, nrounds = 2, objective = "binary:logistic"
+#' )
 #'
 #' importance_matrix <- xgb.importance(colnames(agaricus.train$data), model = bst)
 #'

R-package/R/xgb.plot.multi.trees.R

@@ -43,10 +43,15 @@
 #' @examples
 #'
 #' data(agaricus.train, package='xgboost')
+#' ## Keep the number of threads to 2 for examples
+#' nthread <- 2
+#' data.table::setDTthreads(nthread)
 #'
-#' bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 15,
+#' bst <- xgboost(
-#'                eta = 1, nthread = 2, nrounds = 30, objective = "binary:logistic",
+#'   data = agaricus.train$data, label = agaricus.train$label, max_depth = 15,
-#'                min_child_weight = 50, verbose = 0)
+#'   eta = 1, nthread = nthread, nrounds = 30, objective = "binary:logistic",
+#'   min_child_weight = 50, verbose = 0
+#' )
 #'
 #' p <- xgb.plot.multi.trees(model = bst, features_keep = 3)
 #' print(p)

R-package/R/xgb.plot.shap.R

@@ -74,9 +74,14 @@
 #' data(agaricus.train, package='xgboost')
 #' data(agaricus.test, package='xgboost')
 #'
-#' bst <- xgboost(agaricus.train$data, agaricus.train$label, nrounds = 50,
+#' ## Keep the number of threads to 1 for examples
+#' nthread <- 1
+#' data.table::setDTthreads(nthread)
+#' nrounds <- 20
+#'
+#' bst <- xgboost(agaricus.train$data, agaricus.train$label, nrounds = nrounds,
 #'                eta = 0.1, max_depth = 3, subsample = .5,
-#'                method = "hist", objective = "binary:logistic", nthread = 2, verbose = 0)
+#'                method = "hist", objective = "binary:logistic", nthread = nthread, verbose = 0)
 #'
 #' xgb.plot.shap(agaricus.test$data, model = bst, features = "odor=none")
 #' contr <- predict(bst, agaricus.test$data, predcontrib = TRUE)
@@ -85,12 +90,11 @@
 #'
 #' # multiclass example - plots for each class separately:
 #' nclass <- 3
-#' nrounds <- 20
 #' x <- as.matrix(iris[, -5])
 #' set.seed(123)
 #' is.na(x[sample(nrow(x) * 4, 30)]) <- TRUE # introduce some missing values
 #' mbst <- xgboost(data = x, label = as.numeric(iris$Species) - 1, nrounds = nrounds,
-#'                 max_depth = 2, eta = 0.3, subsample = .5, nthread = 2,
+#'                 max_depth = 2, eta = 0.3, subsample = .5, nthread = nthread,
 #'                 objective = "multi:softprob", num_class = nclass, verbose = 0)
 #' trees0 <- seq(from=0, by=nclass, length.out=nrounds)
 #' col <- rgb(0, 0, 1, 0.5)

R-package/R/xgb.save.R

@@ -25,14 +25,22 @@
 #' @examples
 #' data(agaricus.train, package='xgboost')
 #' data(agaricus.test, package='xgboost')
+#'
+#' ## Keep the number of threads to 1 for examples
+#' nthread <- 1
+#' data.table::setDTthreads(nthread)
+#'
 #' train <- agaricus.train
 #' test <- agaricus.test
-#' bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+#' bst <- xgboost(
-#'                eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
+#'   data = train$data, label = train$label, max_depth = 2, eta = 1,
+#'   nthread = nthread,
+#'   nrounds = 2,
+#'   objective = "binary:logistic"
+#' )
 #' xgb.save(bst, 'xgb.model')
 #' bst <- xgb.load('xgb.model')
 #' if (file.exists('xgb.model')) file.remove('xgb.model')
-#' pred <- predict(bst, test$data)
 #' @export
 xgb.save <- function(model, fname) {
   if (typeof(fname) != "character")

R-package/R/xgb.save.raw.R

@@ -16,13 +16,18 @@
 #' @examples
 #' data(agaricus.train, package='xgboost')
 #' data(agaricus.test, package='xgboost')
+#'
+#' ## Keep the number of threads to 2 for examples
+#' nthread <- 2
+#' data.table::setDTthreads(nthread)
+#'
 #' train <- agaricus.train
 #' test <- agaricus.test
 #' bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
-#'                eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
+#'                eta = 1, nthread = nthread, nrounds = 2,objective = "binary:logistic")
+#'
 #' raw <- xgb.save.raw(bst)
 #' bst <- xgb.load.raw(raw)
-#' pred <- predict(bst, test$data)
 #'
 #' @export
 xgb.save.raw <- function(model, raw_format = "deprecated") {

R-package/R/xgb.train.R

@@ -168,7 +168,8 @@
 #' than the \code{xgboost} interface.
 #'
 #' Parallelization is automatically enabled if \code{OpenMP} is present.
-#' Number of threads can also be manually specified via \code{nthread} parameter.
+#' Number of threads can also be manually specified via the \code{nthread}
+#' parameter.
 #'
 #' The evaluation metric is chosen automatically by XGBoost (according to the objective)
 #' when the \code{eval_metric} parameter is not provided.
@@ -237,17 +238,25 @@
 #' data(agaricus.train, package='xgboost')
 #' data(agaricus.test, package='xgboost')
 #'
-#' dtrain <- with(agaricus.train, xgb.DMatrix(data, label = label, nthread = 2))
+#' ## Keep the number of threads to 1 for examples
-#' dtest <- with(agaricus.test, xgb.DMatrix(data, label = label, nthread = 2))
+#' nthread <- 1
+#' data.table::setDTthreads(nthread)
+#'
+#' dtrain <- with(
+#'   agaricus.train, xgb.DMatrix(data, label = label, nthread = nthread)
+#' )
+#' dtest <- with(
+#'   agaricus.test, xgb.DMatrix(data, label = label, nthread = nthread)
+#' )
 #' watchlist <- list(train = dtrain, eval = dtest)
 #'
 #' ## A simple xgb.train example:
-#' param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = 2,
+#' param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = nthread,
 #'               objective = "binary:logistic", eval_metric = "auc")
 #' bst <- xgb.train(param, dtrain, nrounds = 2, watchlist)
 #'
-#'
+#' ## An xgb.train example where custom objective and evaluation metric are
-#' ## An xgb.train example where custom objective and evaluation metric are used:
+#' ## used:
 #' logregobj <- function(preds, dtrain) {
 #'    labels <- getinfo(dtrain, "label")
 #'    preds <- 1/(1 + exp(-preds))
@@ -263,12 +272,12 @@
 #'
 #' # These functions could be used by passing them either:
 #' #  as 'objective' and 'eval_metric' parameters in the params list:
-#' param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = 2,
+#' param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = nthread,
 #'               objective = logregobj, eval_metric = evalerror)
 #' bst <- xgb.train(param, dtrain, nrounds = 2, watchlist)
 #'
 #' #  or through the ... arguments:
-#' param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = 2)
+#' param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = nthread)
 #' bst <- xgb.train(param, dtrain, nrounds = 2, watchlist,
 #'                  objective = logregobj, eval_metric = evalerror)
 #'
@@ -278,7 +287,7 @@
 #'
 #'
 #' ## An xgb.train example of using variable learning rates at each iteration:
-#' param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = 2,
+#' param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = nthread,
 #'               objective = "binary:logistic", eval_metric = "auc")
 #' my_etas <- list(eta = c(0.5, 0.1))
 #' bst <- xgb.train(param, dtrain, nrounds = 2, watchlist,
@@ -290,7 +299,7 @@
 #'
 #' ## An 'xgboost' interface example:
 #' bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label,
-#'                max_depth = 2, eta = 1, nthread = 2, nrounds = 2,
+#'                max_depth = 2, eta = 1, nthread = nthread, nrounds = 2,
 #'                objective = "binary:logistic")
 #' pred <- predict(bst, agaricus.test$data)
 #'

R-package/man/cb.gblinear.history.Rd

@@ -35,14 +35,18 @@ Callback function expects the following values to be set in its calling frame:
 }
 \examples{
 #### Binary classification:
-#
+
+## Keep the number of threads to 1 for examples
+nthread <- 1
+data.table::setDTthreads(nthread)
+
 # In the iris dataset, it is hard to linearly separate Versicolor class from the rest
 # without considering the 2nd order interactions:
 x <- model.matrix(Species ~ .^2, iris)[,-1]
 colnames(x)
-dtrain <- xgb.DMatrix(scale(x), label = 1*(iris$Species == "versicolor"), nthread = 2)
+dtrain <- xgb.DMatrix(scale(x), label = 1*(iris$Species == "versicolor"), nthread = nthread)
 param <- list(booster = "gblinear", objective = "reg:logistic", eval_metric = "auc",
-              lambda = 0.0003, alpha = 0.0003, nthread = 2)
+              lambda = 0.0003, alpha = 0.0003, nthread = nthread)
 # For 'shotgun', which is a default linear updater, using high eta values may result in
 # unstable behaviour in some datasets. With this simple dataset, however, the high learning
 # rate does not break the convergence, but allows us to illustrate the typical pattern of
@@ -72,9 +76,9 @@ matplot(xgb.gblinear.history(bst)[[3]], type = 'l')
 
 #### Multiclass classification:
 #
-dtrain <- xgb.DMatrix(scale(x), label = as.numeric(iris$Species) - 1, nthread = 1)
+dtrain <- xgb.DMatrix(scale(x), label = as.numeric(iris$Species) - 1, nthread = nthread)
 param <- list(booster = "gblinear", objective = "multi:softprob", num_class = 3,
-              lambda = 0.0003, alpha = 0.0003, nthread = 1)
+              lambda = 0.0003, alpha = 0.0003, nthread = nthread)
 # For the default linear updater 'shotgun' it sometimes is helpful
 # to use smaller eta to reduce instability
 bst <- xgb.train(param, dtrain, list(tr=dtrain), nrounds = 50, eta = 0.5,

R-package/man/predict.xgb.Booster.Rd

@@ -132,11 +132,16 @@ Note also that converting a matrix to \code{\link{xgb.DMatrix}} uses multiple th
 
 data(agaricus.train, package='xgboost')
 data(agaricus.test, package='xgboost')
+
+## Keep the number of threads to 2 for examples
+nthread <- 2
+data.table::setDTthreads(nthread)
+
 train <- agaricus.train
 test <- agaricus.test
 
 bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
-               eta = 0.5, nthread = 2, nrounds = 5, objective = "binary:logistic")
+               eta = 0.5, nthread = nthread, nrounds = 5, objective = "binary:logistic")
 # use all trees by default
 pred <- predict(bst, test$data)
 # use only the 1st tree

R-package/man/xgb.DMatrix.Rd

@@ -38,7 +38,12 @@ Supported input file formats are either a LIBSVM text file or a binary file that
 }
 \examples{
 data(agaricus.train, package='xgboost')
-dtrain <- with(agaricus.train, xgb.DMatrix(data, label = label, nthread = 2))
+## Keep the number of threads to 1 for examples
+nthread <- 1
+data.table::setDTthreads(nthread)
+dtrain <- with(
+  agaricus.train, xgb.DMatrix(data, label = label, nthread = nthread)
+)
 xgb.DMatrix.save(dtrain, 'xgb.DMatrix.data')
 dtrain <- xgb.DMatrix('xgb.DMatrix.data')
 if (file.exists('xgb.DMatrix.data')) file.remove('xgb.DMatrix.data')

R-package/man/xgb.config.Rd

@@ -19,10 +19,15 @@ Accessors for model parameters as JSON string.
 }
 \examples{
 data(agaricus.train, package='xgboost')
+## Keep the number of threads to 1 for examples
+nthread <- 1
+data.table::setDTthreads(nthread)
 train <- agaricus.train
 
-bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+bst <- xgboost(
-               eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic")
+  data = train$data, label = train$label, max_depth = 2,
+  eta = 1, nthread = nthread, nrounds = 2, objective = "binary:logistic"
+)
 config <- xgb.config(bst)
 
 }

R-package/man/xgb.load.Rd

@@ -27,14 +27,23 @@ not \code{xgb.load}.
 \examples{
 data(agaricus.train, package='xgboost')
 data(agaricus.test, package='xgboost')
+
+## Keep the number of threads to 1 for examples
+nthread <- 1
+data.table::setDTthreads(nthread)
+
 train <- agaricus.train
 test <- agaricus.test
-bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+bst <- xgboost(
-               eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
+  data = train$data, label = train$label, max_depth = 2, eta = 1,
+  nthread = nthread,
+  nrounds = 2,
+  objective = "binary:logistic"
+)
+
 xgb.save(bst, 'xgb.model')
 bst <- xgb.load('xgb.model')
 if (file.exists('xgb.model')) file.remove('xgb.model')
-pred <- predict(bst, test$data)
 }
 \seealso{
 \code{\link{xgb.save}}, \code{\link{xgb.Booster.complete}}.

R-package/man/xgb.model.dt.tree.Rd

@@ -66,9 +66,12 @@ Parse a boosted tree model text dump into a \code{data.table} structure.
 # Basic use:
 
 data(agaricus.train, package='xgboost')
+## Keep the number of threads to 1 for examples
+nthread <- 1
+data.table::setDTthreads(nthread)
 
 bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 2,
-               eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
+               eta = 1, nthread = nthread, nrounds = 2,objective = "binary:logistic")
 
 (dt <- xgb.model.dt.tree(colnames(agaricus.train$data), bst))
 

R-package/man/xgb.plot.deepness.Rd

@@ -61,10 +61,13 @@ This function was inspired by the blog post
 \examples{
 
 data(agaricus.train, package='xgboost')
+## Keep the number of threads to 2 for examples
+nthread <- 2
+data.table::setDTthreads(nthread)
 
-# Change max_depth to a higher number to get a more significant result
+## Change max_depth to a higher number to get a more significant result
 bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 6,
-               eta = 0.1, nthread = 2, nrounds = 50, objective = "binary:logistic",
+               eta = 0.1, nthread = nthread, nrounds = 50, objective = "binary:logistic",
                subsample = 0.5, min_child_weight = 2)
 
 xgb.plot.deepness(bst)

R-package/man/xgb.plot.importance.Rd

@@ -77,9 +77,14 @@ with bar colors corresponding to different clusters that have somewhat similar i
 }
 \examples{
 data(agaricus.train)
+## Keep the number of threads to 2 for examples
+nthread <- 2
+data.table::setDTthreads(nthread)
 
-bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 3,
+bst <- xgboost(
-               eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic")
+  data = agaricus.train$data, label = agaricus.train$label, max_depth = 3,
+  eta = 1, nthread = nthread, nrounds = 2, objective = "binary:logistic"
+)
 
 importance_matrix <- xgb.importance(colnames(agaricus.train$data), model = bst)
 

R-package/man/xgb.plot.multi.trees.Rd

@@ -63,10 +63,15 @@ This function is inspired by this blog post:
 \examples{
 
 data(agaricus.train, package='xgboost')
+## Keep the number of threads to 2 for examples
+nthread <- 2
+data.table::setDTthreads(nthread)
 
-bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 15,
+bst <- xgboost(
-               eta = 1, nthread = 2, nrounds = 30, objective = "binary:logistic",
+  data = agaricus.train$data, label = agaricus.train$label, max_depth = 15,
-               min_child_weight = 50, verbose = 0)
+  eta = 1, nthread = nthread, nrounds = 30, objective = "binary:logistic",
+  min_child_weight = 50, verbose = 0
+)
 
 p <- xgb.plot.multi.trees(model = bst, features_keep = 3)
 print(p)

R-package/man/xgb.plot.shap.Rd

@@ -124,9 +124,14 @@ a meaningful thing to do.
 data(agaricus.train, package='xgboost')
 data(agaricus.test, package='xgboost')
 
-bst <- xgboost(agaricus.train$data, agaricus.train$label, nrounds = 50,
+## Keep the number of threads to 1 for examples
+nthread <- 1
+data.table::setDTthreads(nthread)
+nrounds <- 20
+
+bst <- xgboost(agaricus.train$data, agaricus.train$label, nrounds = nrounds,
                eta = 0.1, max_depth = 3, subsample = .5,
-               method = "hist", objective = "binary:logistic", nthread = 2, verbose = 0)
+               method = "hist", objective = "binary:logistic", nthread = nthread, verbose = 0)
 
 xgb.plot.shap(agaricus.test$data, model = bst, features = "odor=none")
 contr <- predict(bst, agaricus.test$data, predcontrib = TRUE)
@@ -135,12 +140,11 @@ xgb.ggplot.shap.summary(agaricus.test$data, contr, model = bst, top_n = 12)  # S
 
 # multiclass example - plots for each class separately:
 nclass <- 3
-nrounds <- 20
 x <- as.matrix(iris[, -5])
 set.seed(123)
 is.na(x[sample(nrow(x) * 4, 30)]) <- TRUE # introduce some missing values
 mbst <- xgboost(data = x, label = as.numeric(iris$Species) - 1, nrounds = nrounds,
-                max_depth = 2, eta = 0.3, subsample = .5, nthread = 2,
+                max_depth = 2, eta = 0.3, subsample = .5, nthread = nthread,
                 objective = "multi:softprob", num_class = nclass, verbose = 0)
 trees0 <- seq(from=0, by=nclass, length.out=nrounds)
 col <- rgb(0, 0, 1, 0.5)

R-package/man/xgb.save.Rd

@@ -31,14 +31,22 @@ releases of XGBoost.
 \examples{
 data(agaricus.train, package='xgboost')
 data(agaricus.test, package='xgboost')
+
+## Keep the number of threads to 1 for examples
+nthread <- 1
+data.table::setDTthreads(nthread)
+
 train <- agaricus.train
 test <- agaricus.test
-bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+bst <- xgboost(
-               eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
+  data = train$data, label = train$label, max_depth = 2, eta = 1,
+  nthread = nthread,
+  nrounds = 2,
+  objective = "binary:logistic"
+)
 xgb.save(bst, 'xgb.model')
 bst <- xgb.load('xgb.model')
 if (file.exists('xgb.model')) file.remove('xgb.model')
-pred <- predict(bst, test$data)
 }
 \seealso{
 \code{\link{xgb.load}}, \code{\link{xgb.Booster.complete}}.

R-package/man/xgb.save.raw.Rd

@@ -25,12 +25,17 @@ Save xgboost model from xgboost or xgb.train
 \examples{
 data(agaricus.train, package='xgboost')
 data(agaricus.test, package='xgboost')
+
+## Keep the number of threads to 2 for examples
+nthread <- 2
+data.table::setDTthreads(nthread)
+
 train <- agaricus.train
 test <- agaricus.test
 bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
-               eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
+               eta = 1, nthread = nthread, nrounds = 2,objective = "binary:logistic")
+
 raw <- xgb.save.raw(bst)
 bst <- xgb.load.raw(raw)
-pred <- predict(bst, test$data)
 
 }

R-package/man/xgb.train.Rd

@@ -250,7 +250,8 @@ customized objective and evaluation metric functions, therefore it is more flexi
 than the \code{xgboost} interface.
 
 Parallelization is automatically enabled if \code{OpenMP} is present.
-Number of threads can also be manually specified via \code{nthread} parameter.
+Number of threads can also be manually specified via the \code{nthread}
+parameter.
 
 The evaluation metric is chosen automatically by XGBoost (according to the objective)
 when the \code{eval_metric} parameter is not provided.
@@ -286,17 +287,25 @@ The following callbacks are automatically created when certain parameters are se
 data(agaricus.train, package='xgboost')
 data(agaricus.test, package='xgboost')
 
-dtrain <- with(agaricus.train, xgb.DMatrix(data, label = label, nthread = 2))
+## Keep the number of threads to 1 for examples
-dtest <- with(agaricus.test, xgb.DMatrix(data, label = label, nthread = 2))
+nthread <- 1
+data.table::setDTthreads(nthread)
+
+dtrain <- with(
+  agaricus.train, xgb.DMatrix(data, label = label, nthread = nthread)
+)
+dtest <- with(
+  agaricus.test, xgb.DMatrix(data, label = label, nthread = nthread)
+)
 watchlist <- list(train = dtrain, eval = dtest)
 
 ## A simple xgb.train example:
-param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = 2,
+param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = nthread,
               objective = "binary:logistic", eval_metric = "auc")
 bst <- xgb.train(param, dtrain, nrounds = 2, watchlist)
 
-
+## An xgb.train example where custom objective and evaluation metric are
-## An xgb.train example where custom objective and evaluation metric are used:
+## used:
 logregobj <- function(preds, dtrain) {
    labels <- getinfo(dtrain, "label")
    preds <- 1/(1 + exp(-preds))
@@ -312,12 +321,12 @@ evalerror <- function(preds, dtrain) {
 
 # These functions could be used by passing them either:
 #  as 'objective' and 'eval_metric' parameters in the params list:
-param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = 2,
+param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = nthread,
               objective = logregobj, eval_metric = evalerror)
 bst <- xgb.train(param, dtrain, nrounds = 2, watchlist)
 
 #  or through the ... arguments:
-param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = 2)
+param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = nthread)
 bst <- xgb.train(param, dtrain, nrounds = 2, watchlist,
                  objective = logregobj, eval_metric = evalerror)
 
@@ -327,7 +336,7 @@ bst <- xgb.train(param, dtrain, nrounds = 2, watchlist,
 
 
 ## An xgb.train example of using variable learning rates at each iteration:
-param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = 2,
+param <- list(max_depth = 2, eta = 1, verbose = 0, nthread = nthread,
               objective = "binary:logistic", eval_metric = "auc")
 my_etas <- list(eta = c(0.5, 0.1))
 bst <- xgb.train(param, dtrain, nrounds = 2, watchlist,
@@ -339,7 +348,7 @@ bst <- xgb.train(param, dtrain, nrounds = 25, watchlist,
 
 ## An 'xgboost' interface example:
 bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label,
-               max_depth = 2, eta = 1, nthread = 2, nrounds = 2,
+               max_depth = 2, eta = 1, nthread = nthread, nrounds = 2,
                objective = "binary:logistic")
 pred <- predict(bst, agaricus.test$data)
 

R-package/tests/helper_scripts/run-examples.R

@@ -0,0 +1,25 @@
+## Helper script for running individual examples.
+library(pkgload)
+library(xgboost)
+
+files <- list.files("./man")
+
+
+run_example_timeit <- function(f) {
+  path <- paste("./man/", f, sep = "")
+  print(paste("Test", f))
+  flush.console()
+  t0 <- proc.time()
+  run_example(path)
+  t1 <- proc.time()
+  list(file = f, time = t1 - t0)
+}
+
+timings <- lapply(files, run_example_timeit)
+
+for (t in timings) {
+  ratio <- t$time[1] / t$time[3]
+  if (!is.na(ratio) && !is.infinite(ratio) && ratio >= 2.5) {
+    print(paste("Offending example:", t$file, ratio))
+  }
+}

R-package/tests/testthat/test_basic.R

@@ -1,7 +1,7 @@
 context("basic functions")
 
-data(agaricus.train, package = 'xgboost')
+data(agaricus.train, package = "xgboost")
-data(agaricus.test, package = 'xgboost')
+data(agaricus.test, package = "xgboost")
 train <- agaricus.train
 test <- agaricus.test
 set.seed(1994)
@@ -9,15 +9,20 @@ set.seed(1994)
 # disable some tests for Win32
 windows_flag <- .Platform$OS.type == "windows" &&
   .Machine$sizeof.pointer != 8
-solaris_flag <- (Sys.info()['sysname'] == "SunOS")
+solaris_flag <- (Sys.info()["sysname"] == "SunOS")
+n_threads <- 1
+
 
 test_that("train and predict binary classification", {
   nrounds <- 2
   expect_output(
-    bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+    bst <- xgboost(
-                  eta = 1, nthread = 2, nrounds = nrounds, objective = "binary:logistic",
+      data = train$data, label = train$label, max_depth = 2,
-                  eval_metric = "error")
+      eta = 1, nthread = n_threads, nrounds = nrounds,
-  , "train-error")
+      objective = "binary:logistic", eval_metric = "error"
+    ),
+    "train-error"
+  )
   expect_equal(class(bst), "xgb.Booster")
   expect_equal(bst$niter, nrounds)
   expect_false(is.null(bst$evaluation_log))
@@ -46,26 +51,39 @@ test_that("parameter validation works", {
   d <- cbind(
     x1 = rnorm(10),
     x2 = rnorm(10),
-    x3 = rnorm(10))
+    x3 = rnorm(10)
+  )
   y <- d[, "x1"] + d[, "x2"]^2 +
     ifelse(d[, "x3"] > .5, d[, "x3"]^2, 2^d[, "x3"]) +
     rnorm(10)
-  dtrain <- xgb.DMatrix(data = d, info = list(label = y))
+  dtrain <- xgb.DMatrix(data = d, info = list(label = y), nthread = n_threads)
 
   correct <- function() {
-    params <- list(max_depth = 2, booster = "dart",
+    params <- list(
-                   rate_drop = 0.5, one_drop = TRUE,
+      max_depth = 2,
-                   objective = "reg:squarederror")
+      booster = "dart",
+      rate_drop = 0.5,
+      one_drop = TRUE,
+      nthread = n_threads,
+      objective = "reg:squarederror"
+    )
     xgb.train(params = params, data = dtrain, nrounds = nrounds)
   }
   expect_silent(correct())
   incorrect <- function() {
-    params <- list(max_depth = 2, booster = "dart",
+    params <- list(
-                   rate_drop = 0.5, one_drop = TRUE,
+      max_depth = 2,
+      booster = "dart",
+      rate_drop = 0.5,
+      one_drop = TRUE,
       objective = "reg:squarederror",
-                   foo = "bar", bar = "foo")
+      nthread = n_threads,
+      foo = "bar",
+      bar = "foo"
+    )
     output <- capture.output(
-      xgb.train(params = params, data = dtrain, nrounds = nrounds))
+      xgb.train(params = params, data = dtrain, nrounds = nrounds)
+    )
     print(output)
   }
   expect_output(incorrect(), '\\\\"bar\\\\", \\\\"foo\\\\"')
@@ -79,7 +97,8 @@ test_that("dart prediction works", {
   d <- cbind(
     x1 = rnorm(100),
     x2 = rnorm(100),
-    x3 = rnorm(100))
+    x3 = rnorm(100)
+  )
   y <- d[, "x1"] + d[, "x2"]^2 +
     ifelse(d[, "x3"] > .5, d[, "x3"]^2, 2^d[, "x3"]) +
     rnorm(100)
@@ -93,7 +112,7 @@ test_that("dart prediction works", {
     rate_drop = 0.5,
     one_drop = TRUE,
     eta = 1,
-    nthread = 2,
+    nthread = n_threads,
     nrounds = nrounds,
     objective = "reg:squarederror"
   )
@@ -105,7 +124,7 @@ test_that("dart prediction works", {
   expect_false(all(matrix(pred_by_xgboost_0, byrow = TRUE) == matrix(pred_by_xgboost_2, byrow = TRUE)))
 
   set.seed(1994)
-  dtrain <- xgb.DMatrix(data = d, info = list(label = y))
+  dtrain <- xgb.DMatrix(data = d, info = list(label = y), nthread = n_threads)
   booster_by_train <- xgb.train(
     params = list(
       booster = "dart",
@@ -113,7 +132,7 @@ test_that("dart prediction works", {
       eta = 1,
       rate_drop = 0.5,
       one_drop = TRUE,
-      nthread = 1,
+      nthread = n_threads,
       objective = "reg:squarederror"
     ),
     data = dtrain,
@@ -132,10 +151,13 @@ test_that("train and predict softprob", {
   lb <- as.numeric(iris$Species) - 1
   set.seed(11)
   expect_output(
-    bst <- xgboost(data = as.matrix(iris[, -5]), label = lb,
+    bst <- xgboost(
-                   max_depth = 3, eta = 0.5, nthread = 2, nrounds = 5,
+      data = as.matrix(iris[, -5]), label = lb,
-                   objective = "multi:softprob", num_class = 3, eval_metric = "merror")
+      max_depth = 3, eta = 0.5, nthread = n_threads, nrounds = 5,
-  , "train-merror")
+      objective = "multi:softprob", num_class = 3, eval_metric = "merror"
+    ),
+    "train-merror"
+  )
   expect_false(is.null(bst$evaluation_log))
   expect_lt(bst$evaluation_log[, min(train_merror)], 0.025)
   expect_equal(bst$niter * 3, xgb.ntree(bst))
@@ -164,9 +186,10 @@ test_that("train and predict softprob", {
     x3 = rnorm(100)
   )
   y <- sample.int(10, 100, replace = TRUE) - 1
-  dtrain <- xgb.DMatrix(data = d, info = list(label = y))
+  dtrain <- xgb.DMatrix(data = d, info = list(label = y), nthread = n_threads)
   booster <- xgb.train(
-    params = list(tree_method = "hist"), data = dtrain, nrounds = 4, num_class = 10,
+    params = list(tree_method = "hist", nthread = n_threads),
+    data = dtrain, nrounds = 4, num_class = 10,
     objective = "multi:softprob"
   )
   predt <- predict(booster, as.matrix(d), reshape = TRUE, strict_shape = FALSE)
@@ -178,10 +201,13 @@ test_that("train and predict softmax", {
   lb <- as.numeric(iris$Species) - 1
   set.seed(11)
   expect_output(
-    bst <- xgboost(data = as.matrix(iris[, -5]), label = lb,
+    bst <- xgboost(
-                   max_depth = 3, eta = 0.5, nthread = 2, nrounds = 5,
+      data = as.matrix(iris[, -5]), label = lb,
-                   objective = "multi:softmax", num_class = 3, eval_metric = "merror")
+      max_depth = 3, eta = 0.5, nthread = n_threads, nrounds = 5,
-  , "train-merror")
+      objective = "multi:softmax", num_class = 3, eval_metric = "merror"
+    ),
+    "train-merror"
+  )
   expect_false(is.null(bst$evaluation_log))
   expect_lt(bst$evaluation_log[, min(train_merror)], 0.025)
   expect_equal(bst$niter * 3, xgb.ntree(bst))
@@ -196,16 +222,19 @@ test_that("train and predict RF", {
   set.seed(11)
   lb <- train$label
   # single iteration
-  bst <- xgboost(data = train$data, label = lb, max_depth = 5,
+  bst <- xgboost(
-                 nthread = 2, nrounds = 1, objective = "binary:logistic", eval_metric = "error",
+    data = train$data, label = lb, max_depth = 5,
-                 num_parallel_tree = 20, subsample = 0.6, colsample_bytree = 0.1)
+    nthread = n_threads,
+    nrounds = 1, objective = "binary:logistic", eval_metric = "error",
+    num_parallel_tree = 20, subsample = 0.6, colsample_bytree = 0.1
+  )
   expect_equal(bst$niter, 1)
   expect_equal(xgb.ntree(bst), 20)
 
   pred <- predict(bst, train$data)
   pred_err <- sum((pred > 0.5) != lb) / length(lb)
   expect_lt(abs(bst$evaluation_log[1, train_error] - pred_err), 10e-6)
-  #expect_lt(pred_err, 0.03)
+  # expect_lt(pred_err, 0.03)
 
   pred <- predict(bst, train$data, ntreelimit = 20)
   pred_err_20 <- sum((pred > 0.5) != lb) / length(lb)
@@ -219,11 +248,13 @@ test_that("train and predict RF with softprob", {
   lb <- as.numeric(iris$Species) - 1
   nrounds <- 15
   set.seed(11)
-  bst <- xgboost(data = as.matrix(iris[, -5]), label = lb,
+  bst <- xgboost(
-                 max_depth = 3, eta = 0.9, nthread = 2, nrounds = nrounds,
+    data = as.matrix(iris[, -5]), label = lb,
+    max_depth = 3, eta = 0.9, nthread = n_threads, nrounds = nrounds,
     objective = "multi:softprob", eval_metric = "merror",
     num_class = 3, verbose = 0,
-                 num_parallel_tree = 4, subsample = 0.5, colsample_bytree = 0.5)
+    num_parallel_tree = 4, subsample = 0.5, colsample_bytree = 0.5
+  )
   expect_equal(bst$niter, 15)
   expect_equal(xgb.ntree(bst), 15 * 3 * 4)
   # predict for all iterations:
@@ -240,18 +271,24 @@ test_that("train and predict RF with softprob", {
 
 test_that("use of multiple eval metrics works", {
   expect_output(
-    bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+    bst <- xgboost(
-                   eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic",
+      data = train$data, label = train$label, max_depth = 2,
-                   eval_metric = 'error', eval_metric = 'auc', eval_metric = "logloss")
+      eta = 1, nthread = n_threads, nrounds = 2, objective = "binary:logistic",
-  , "train-error.*train-auc.*train-logloss")
+      eval_metric = "error", eval_metric = "auc", eval_metric = "logloss"
+    ),
+    "train-error.*train-auc.*train-logloss"
+  )
   expect_false(is.null(bst$evaluation_log))
   expect_equal(dim(bst$evaluation_log), c(2, 4))
   expect_equal(colnames(bst$evaluation_log), c("iter", "train_error", "train_auc", "train_logloss"))
   expect_output(
-    bst2 <- xgboost(data = train$data, label = train$label, max_depth = 2,
+    bst2 <- xgboost(
-                    eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic",
+      data = train$data, label = train$label, max_depth = 2,
-                    eval_metric = list("error", "auc", "logloss"))
+      eta = 1, nthread = n_threads, nrounds = 2, objective = "binary:logistic",
-  , "train-error.*train-auc.*train-logloss")
+      eval_metric = list("error", "auc", "logloss")
+    ),
+    "train-error.*train-auc.*train-logloss"
+  )
   expect_false(is.null(bst2$evaluation_log))
   expect_equal(dim(bst2$evaluation_log), c(2, 4))
   expect_equal(colnames(bst2$evaluation_log), c("iter", "train_error", "train_auc", "train_logloss"))
@@ -259,9 +296,11 @@ test_that("use of multiple eval metrics works", {
 
 
 test_that("training continuation works", {
-  dtrain <- xgb.DMatrix(train$data, label = train$label)
+  dtrain <- xgb.DMatrix(train$data, label = train$label, nthread = n_threads)
   watchlist <- list(train = dtrain)
-  param <- list(objective = "binary:logistic", max_depth = 2, eta = 1, nthread = 2)
+  param <- list(
+    objective = "binary:logistic", max_depth = 2, eta = 1, nthread = n_threads
+  )
 
   # for the reference, use 4 iterations at once:
   set.seed(11)
@@ -271,30 +310,33 @@ test_that("training continuation works", {
   bst1 <- xgb.train(param, dtrain, nrounds = 2, watchlist, verbose = 0)
   # continue for two more:
   bst2 <- xgb.train(param, dtrain, nrounds = 2, watchlist, verbose = 0, xgb_model = bst1)
-  if (!windows_flag && !solaris_flag)
+  if (!windows_flag && !solaris_flag) {
     expect_equal(bst$raw, bst2$raw)
+  }
   expect_false(is.null(bst2$evaluation_log))
   expect_equal(dim(bst2$evaluation_log), c(4, 2))
   expect_equal(bst2$evaluation_log, bst$evaluation_log)
   # test continuing from raw model data
   bst2 <- xgb.train(param, dtrain, nrounds = 2, watchlist, verbose = 0, xgb_model = bst1$raw)
-  if (!windows_flag && !solaris_flag)
+  if (!windows_flag && !solaris_flag) {
     expect_equal(bst$raw, bst2$raw)
+  }
   expect_equal(dim(bst2$evaluation_log), c(2, 2))
   # test continuing from a model in file
   xgb.save(bst1, "xgboost.json")
   bst2 <- xgb.train(param, dtrain, nrounds = 2, watchlist, verbose = 0, xgb_model = "xgboost.json")
-  if (!windows_flag && !solaris_flag)
+  if (!windows_flag && !solaris_flag) {
     expect_equal(bst$raw, bst2$raw)
+  }
   expect_equal(dim(bst2$evaluation_log), c(2, 2))
   file.remove("xgboost.json")
 })
 
 test_that("model serialization works", {
   out_path <- "model_serialization"
-  dtrain <- xgb.DMatrix(train$data, label = train$label)
+  dtrain <- xgb.DMatrix(train$data, label = train$label, nthread = n_threads)
   watchlist <- list(train = dtrain)
-  param <- list(objective = "binary:logistic")
+  param <- list(objective = "binary:logistic", nthread = n_threads)
   booster <- xgb.train(param, dtrain, nrounds = 4, watchlist)
   raw <- xgb.serialize(booster)
   saveRDS(raw, out_path)
@@ -309,11 +351,14 @@ test_that("model serialization works", {
 test_that("xgb.cv works", {
   set.seed(11)
   expect_output(
-    cv <- xgb.cv(data = train$data, label = train$label, max_depth = 2, nfold = 5,
+    cv <- xgb.cv(
-                 eta = 1., nthread = 2, nrounds = 2, objective = "binary:logistic",
+      data = train$data, label = train$label, max_depth = 2, nfold = 5,
-                 eval_metric = "error", verbose = TRUE)
+      eta = 1., nthread = n_threads, nrounds = 2, objective = "binary:logistic",
-  , "train-error:")
+      eval_metric = "error", verbose = TRUE
-  expect_is(cv, 'xgb.cv.synchronous')
+    ),
+    "train-error:"
+  )
+  expect_is(cv, "xgb.cv.synchronous")
   expect_false(is.null(cv$evaluation_log))
   expect_lt(cv$evaluation_log[, min(test_error_mean)], 0.03)
   expect_lt(cv$evaluation_log[, min(test_error_std)], 0.008)
@@ -326,15 +371,19 @@ test_that("xgb.cv works", {
 })
 
 test_that("xgb.cv works with stratified folds", {
-  dtrain <- xgb.DMatrix(train$data, label = train$label)
+  dtrain <- xgb.DMatrix(train$data, label = train$label, nthread = n_threads)
   set.seed(314159)
-  cv <- xgb.cv(data = dtrain, max_depth = 2, nfold = 5,
+  cv <- xgb.cv(
-               eta = 1., nthread = 2, nrounds = 2, objective = "binary:logistic",
+    data = dtrain, max_depth = 2, nfold = 5,
-               verbose = TRUE, stratified = FALSE)
+    eta = 1., nthread = n_threads, nrounds = 2, objective = "binary:logistic",
+    verbose = TRUE, stratified = FALSE
+  )
   set.seed(314159)
-  cv2 <- xgb.cv(data = dtrain, max_depth = 2, nfold = 5,
+  cv2 <- xgb.cv(
-                eta = 1., nthread = 2, nrounds = 2, objective = "binary:logistic",
+    data = dtrain, max_depth = 2, nfold = 5,
-                verbose = TRUE, stratified = TRUE)
+    eta = 1., nthread = n_threads, nrounds = 2, objective = "binary:logistic",
+    verbose = TRUE, stratified = TRUE
+  )
   # Stratified folds should result in a different evaluation logs
   expect_true(all(cv$evaluation_log[, test_logloss_mean] != cv2$evaluation_log[, test_logloss_mean]))
 })
@@ -342,40 +391,57 @@ test_that("xgb.cv works with stratified folds", {
 test_that("train and predict with non-strict classes", {
   # standard dense matrix input
   train_dense <- as.matrix(train$data)
-  bst <- xgboost(data = train_dense, label = train$label, max_depth = 2,
+  bst <- xgboost(
-                 eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic", verbose = 0)
+    data = train_dense, label = train$label, max_depth = 2,
+    eta = 1, nthread = n_threads, nrounds = 2, objective = "binary:logistic",
+    verbose = 0
+  )
   pr0 <- predict(bst, train_dense)
 
   # dense matrix-like input of non-matrix class
-  class(train_dense) <- 'shmatrix'
+  class(train_dense) <- "shmatrix"
   expect_true(is.matrix(train_dense))
   expect_error(
-    bst <- xgboost(data = train_dense, label = train$label, max_depth = 2,
+    bst <- xgboost(
-                   eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic", verbose = 0)
+      data = train_dense, label = train$label, max_depth = 2,
-    , regexp = NA)
+      eta = 1, nthread = n_threads, nrounds = 2, objective = "binary:logistic",
+      verbose = 0
+    ),
+    regexp = NA
+  )
   expect_error(pr <- predict(bst, train_dense), regexp = NA)
   expect_equal(pr0, pr)
 
   # dense matrix-like input of non-matrix class with some inheritance
-  class(train_dense) <- c('pphmatrix', 'shmatrix')
+  class(train_dense) <- c("pphmatrix", "shmatrix")
   expect_true(is.matrix(train_dense))
   expect_error(
-    bst <- xgboost(data = train_dense, label = train$label, max_depth = 2,
+    bst <- xgboost(
-                   eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic", verbose = 0)
+      data = train_dense, label = train$label, max_depth = 2,
-    , regexp = NA)
+      eta = 1, nthread = n_threads, nrounds = 2, objective = "binary:logistic",
+      verbose = 0
+    ),
+    regexp = NA
+  )
   expect_error(pr <- predict(bst, train_dense), regexp = NA)
   expect_equal(pr0, pr)
 
   # when someone inherits from xgb.Booster, it should still be possible to use it as xgb.Booster
-  class(bst) <- c('super.Booster', 'xgb.Booster')
+  class(bst) <- c("super.Booster", "xgb.Booster")
   expect_error(pr <- predict(bst, train_dense), regexp = NA)
   expect_equal(pr0, pr)
 })
 
 test_that("max_delta_step works", {
-  dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label)
+  dtrain <- xgb.DMatrix(
+    agaricus.train$data, label = agaricus.train$label, nthread = n_threads
+  )
   watchlist <- list(train = dtrain)
-  param <- list(objective = "binary:logistic", eval_metric = "logloss", max_depth = 2, nthread = 2, eta = 0.5)
+  param <- list(
+    objective = "binary:logistic", eval_metric = "logloss", max_depth = 2,
+    nthread = n_threads,
+    eta = 0.5
+  )
   nrounds <- 5
   # model with no restriction on max_delta_step
   bst1 <- xgb.train(param, dtrain, nrounds, watchlist, verbose = 1)
@@ -395,14 +461,16 @@ test_that("colsample_bytree works", {
   test_y <- as.numeric(rowSums(test_x) > 0)
   colnames(train_x) <- paste0("Feature_", sprintf("%03d", 1:100))
   colnames(test_x) <- paste0("Feature_", sprintf("%03d", 1:100))
-  dtrain <- xgb.DMatrix(train_x, label = train_y)
+  dtrain <- xgb.DMatrix(train_x, label = train_y, nthread = n_threads)
-  dtest <- xgb.DMatrix(test_x, label = test_y)
+  dtest <- xgb.DMatrix(test_x, label = test_y, nthread = n_threads)
   watchlist <- list(train = dtrain, eval = dtest)
   ## Use colsample_bytree = 0.01, so that roughly one out of 100 features is chosen for
   ## each tree
-  param <- list(max_depth = 2, eta = 0, nthread = 2,
+  param <- list(
+    max_depth = 2, eta = 0, nthread = n_threads,
     colsample_bytree = 0.01, objective = "binary:logistic",
-                eval_metric = "auc")
+    eval_metric = "auc"
+  )
   set.seed(2)
   bst <- xgb.train(param, dtrain, nrounds = 100, watchlist, verbose = 0)
   xgb.importance(model = bst)
@@ -412,9 +480,11 @@ test_that("colsample_bytree works", {
 })
 
 test_that("Configuration works", {
-  bst <- xgboost(data = train$data, label = train$label, max_depth = 2,
+  bst <- xgboost(
-                 eta = 1, nthread = 2, nrounds = 2, objective = "binary:logistic",
+    data = train$data, label = train$label, max_depth = 2,
-                 eval_metric = 'error', eval_metric = 'auc', eval_metric = "logloss")
+    eta = 1, nthread = n_threads, nrounds = 2, objective = "binary:logistic",
+    eval_metric = "error", eval_metric = "auc", eval_metric = "logloss"
+  )
   config <- xgb.config(bst)
   xgb.config(bst) <- config
   reloaded_config <- xgb.config(bst)
@@ -451,22 +521,26 @@ test_that("strict_shape works", {
     y <- as.numeric(iris$Species) - 1
     X <- as.matrix(iris[, -5])
 
-    bst <- xgboost(data = X, label = y,
+    bst <- xgboost(
-                   max_depth = 2, nrounds = n_rounds,
+      data = X, label = y,
-                   objective = "multi:softprob", num_class = 3, eval_metric = "merror")
+      max_depth = 2, nrounds = n_rounds, nthread = n_threads,
+      objective = "multi:softprob", num_class = 3, eval_metric = "merror"
+    )
 
     test_strict_shape(bst, X, 3)
   }
 
 
   test_agaricus <- function() {
-    data(agaricus.train, package = 'xgboost')
+    data(agaricus.train, package = "xgboost")
     X <- agaricus.train$data
     y <- agaricus.train$label
 
-    bst <- xgboost(data = X, label = y, max_depth = 2,
+    bst <- xgboost(
+      data = X, label = y, max_depth = 2, nthread = n_threads,
       nrounds = n_rounds, objective = "binary:logistic",
-                   eval_metric = 'error', eval_metric = 'auc', eval_metric = "logloss")
+      eval_metric = "error", eval_metric = "auc", eval_metric = "logloss"
+    )
 
     test_strict_shape(bst, X, 1)
   }
@@ -481,8 +555,10 @@ test_that("'predict' accepts CSR data", {
   x_csc <- as(X[1L, , drop = FALSE], "CsparseMatrix")
   x_csr <- as(x_csc, "RsparseMatrix")
   x_spv <- as(x_csc, "sparseVector")
-  bst <- xgboost(data = X, label = y, objective = "binary:logistic",
+  bst <- xgboost(
-                 nrounds = 5L, verbose = FALSE)
+    data = X, label = y, objective = "binary:logistic",
+    nrounds = 5L, verbose = FALSE, nthread = n_threads,
+  )
   p_csc <- predict(bst, x_csc)
   p_csr <- predict(bst, x_csr)
   p_spv <- predict(bst, x_spv)

R-package/tests/testthat/test_callbacks.R

@@ -6,6 +6,8 @@ data(agaricus.test, package = 'xgboost')
 train <- agaricus.train
 test <- agaricus.test
 
+n_threads <- 2
+
 # add some label noise for early stopping tests
 add.noise <- function(label, frac) {
   inoise <- sample(length(label), length(label) * frac)
@@ -15,15 +17,15 @@ add.noise <- function(label, frac) {
 set.seed(11)
 ltrain <- add.noise(train$label, 0.2)
 ltest <- add.noise(test$label, 0.2)
-dtrain <- xgb.DMatrix(train$data, label = ltrain)
+dtrain <- xgb.DMatrix(train$data, label = ltrain, nthread = n_threads)
-dtest <- xgb.DMatrix(test$data, label = ltest)
+dtest <- xgb.DMatrix(test$data, label = ltest, nthread = n_threads)
 watchlist <- list(train = dtrain, test = dtest)
 
 
 err <- function(label, pr) sum((pr > 0.5) != label) / length(label)
 
 param <- list(objective = "binary:logistic", eval_metric = "error",
-              max_depth = 2, nthread = 2)
+              max_depth = 2, nthread = n_threads)
 
 
 test_that("cb.print.evaluation works as expected", {
@@ -103,7 +105,7 @@ test_that("cb.evaluation.log works as expected", {
 
 
 param <- list(objective = "binary:logistic", eval_metric = "error",
-              max_depth = 4, nthread = 2)
+              max_depth = 4, nthread = n_threads)
 
 test_that("can store evaluation_log without printing", {
   expect_silent(
@@ -179,8 +181,10 @@ test_that("cb.save.model works as expected", {
   expect_true(file.exists('xgboost_01.json'))
   expect_true(file.exists('xgboost_02.json'))
   b1 <- xgb.load('xgboost_01.json')
+  xgb.parameters(b1) <- list(nthread = 2)
   expect_equal(xgb.ntree(b1), 1)
   b2 <- xgb.load('xgboost_02.json')
+  xgb.parameters(b2) <- list(nthread = 2)
   expect_equal(xgb.ntree(b2), 2)
 
   xgb.config(b2) <- xgb.config(bst)
@@ -267,7 +271,8 @@ test_that("early stopping works with titanic", {
     objective = "binary:logistic",
     eval_metric = "auc",
     nrounds = 100,
-    early_stopping_rounds = 3
+    early_stopping_rounds = 3,
+    nthread = n_threads
   )
 
   expect_true(TRUE)  # should not crash
@@ -308,7 +313,7 @@ test_that("prediction in xgb.cv works", {
 
 test_that("prediction in xgb.cv works for gblinear too", {
   set.seed(11)
-  p <- list(booster = 'gblinear', objective = "reg:logistic", nthread = 2)
+  p <- list(booster = 'gblinear', objective = "reg:logistic", nthread = n_threads)
   cv <- xgb.cv(p, dtrain, nfold = 5, eta = 0.5, nrounds = 2, prediction = TRUE, verbose = 0)
   expect_false(is.null(cv$evaluation_log))
   expect_false(is.null(cv$pred))
@@ -341,7 +346,7 @@ test_that("prediction in xgb.cv for softprob works", {
   set.seed(11)
   expect_warning(
     cv <- xgb.cv(data = as.matrix(iris[, -5]), label = lb, nfold = 4,
-                 eta = 0.5, nrounds = 5, max_depth = 3, nthread = 2,
+                 eta = 0.5, nrounds = 5, max_depth = 3, nthread = n_threads,
                  subsample = 0.8, gamma = 2, verbose = 0,
                  prediction = TRUE, objective = "multi:softprob", num_class = 3)
   , NA)

R-package/tests/testthat/test_custom_objective.R

@@ -2,10 +2,16 @@ context('Test models with custom objective')
 
 set.seed(1994)
 
+n_threads <- 2
+
 data(agaricus.train, package = 'xgboost')
 data(agaricus.test, package = 'xgboost')
-dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label)
+dtrain <- xgb.DMatrix(
-dtest <- xgb.DMatrix(agaricus.test$data, label = agaricus.test$label)
+  agaricus.train$data, label = agaricus.train$label, nthread = n_threads
+)
+dtest <- xgb.DMatrix(
+  agaricus.test$data, label = agaricus.test$label, nthread = n_threads
+)
 watchlist <- list(eval = dtest, train = dtrain)
 
 logregobj <- function(preds, dtrain) {
@@ -22,7 +28,7 @@ evalerror <- function(preds, dtrain) {
   return(list(metric = "error", value = err))
 }
 
-param <- list(max_depth = 2, eta = 1, nthread = 2,
+param <- list(max_depth = 2, eta = 1, nthread = n_threads,
               objective = logregobj, eval_metric = evalerror)
 num_round <- 2
 
@@ -67,7 +73,7 @@ test_that("custom objective using DMatrix attr works", {
 test_that("custom objective with multi-class shape", {
   data <- as.matrix(iris[, -5])
   label <-  as.numeric(iris$Species) - 1
-  dtrain <- xgb.DMatrix(data = data, label = label)
+  dtrain <- xgb.DMatrix(data = data, label = label, nthread = n_threads)
   n_classes <- 3
 
   fake_softprob <- function(preds, dtrain) {

R-package/tests/testthat/test_dmatrix.R

@@ -5,19 +5,21 @@ data(agaricus.test, package = "xgboost")
 test_data <- agaricus.test$data[1:100, ]
 test_label <- agaricus.test$label[1:100]
 
+n_threads <- 2
+
 test_that("xgb.DMatrix: basic construction", {
   # from sparse matrix
-  dtest1 <- xgb.DMatrix(test_data, label = test_label)
+  dtest1 <- xgb.DMatrix(test_data, label = test_label, nthread = n_threads)
 
   # from dense matrix
-  dtest2 <- xgb.DMatrix(as.matrix(test_data), label = test_label)
+  dtest2 <- xgb.DMatrix(as.matrix(test_data), label = test_label, nthread = n_threads)
   expect_equal(getinfo(dtest1, "label"), getinfo(dtest2, "label"))
   expect_equal(dim(dtest1), dim(dtest2))
 
   # from dense integer matrix
   int_data <- as.matrix(test_data)
   storage.mode(int_data) <- "integer"
-  dtest3 <- xgb.DMatrix(int_data, label = test_label)
+  dtest3 <- xgb.DMatrix(int_data, label = test_label, nthread = n_threads)
   expect_equal(dim(dtest1), dim(dtest3))
 
   n_samples <- 100
@@ -29,15 +31,15 @@ test_that("xgb.DMatrix: basic construction", {
   X <- matrix(X, nrow = n_samples)
   y <- rbinom(n = n_samples, size = 1, prob = 1 / 2)
 
-  fd <- xgb.DMatrix(X, label = y, missing = 1)
+  fd <- xgb.DMatrix(X, label = y, missing = 1, nthread = n_threads)
 
   dgc <- as(X, "dgCMatrix")
-  fdgc <- xgb.DMatrix(dgc, label = y, missing = 1.0)
+  fdgc <- xgb.DMatrix(dgc, label = y, missing = 1.0, nthread = n_threads)
 
   dgr <- as(X, "dgRMatrix")
-  fdgr <- xgb.DMatrix(dgr, label = y, missing = 1)
+  fdgr <- xgb.DMatrix(dgr, label = y, missing = 1, nthread = n_threads)
 
-  params <- list(tree_method = "hist")
+  params <- list(tree_method = "hist", nthread = n_threads)
   bst_fd <- xgb.train(
     params, nrounds = 8, fd, watchlist = list(train = fd)
   )
@@ -64,12 +66,12 @@ test_that("xgb.DMatrix: NA", {
   )
   x[1, "x1"] <- NA
 
-  m <- xgb.DMatrix(x)
+  m <- xgb.DMatrix(x, nthread = n_threads)
   xgb.DMatrix.save(m, "int.dmatrix")
 
   x <- matrix(as.numeric(x), nrow = n_samples, ncol = 2)
   colnames(x) <- c("x1", "x2")
-  m <- xgb.DMatrix(x)
+  m <- xgb.DMatrix(x, nthread = n_threads)
 
   xgb.DMatrix.save(m, "float.dmatrix")
 
@@ -94,7 +96,7 @@ test_that("xgb.DMatrix: NA", {
 
 test_that("xgb.DMatrix: saving, loading", {
   # save to a local file
-  dtest1 <- xgb.DMatrix(test_data, label = test_label)
+  dtest1 <- xgb.DMatrix(test_data, label = test_label, nthread = n_threads)
   tmp_file <- tempfile('xgb.DMatrix_')
   on.exit(unlink(tmp_file))
   expect_true(xgb.DMatrix.save(dtest1, tmp_file))
@@ -109,13 +111,17 @@ test_that("xgb.DMatrix: saving, loading", {
   tmp_file <- tempfile(fileext = ".libsvm")
   writeLines(tmp, tmp_file)
   expect_true(file.exists(tmp_file))
-  dtest4 <- xgb.DMatrix(paste(tmp_file, "?format=libsvm", sep = ""), silent = TRUE)
+  dtest4 <- xgb.DMatrix(
+    paste(tmp_file, "?format=libsvm", sep = ""), silent = TRUE, nthread = n_threads
+  )
   expect_equal(dim(dtest4), c(3, 4))
   expect_equal(getinfo(dtest4, 'label'), c(0, 1, 0))
 
   # check that feature info is saved
   data(agaricus.train, package = 'xgboost')
-  dtrain <- xgb.DMatrix(data = agaricus.train$data, label = agaricus.train$label)
+  dtrain <- xgb.DMatrix(
+    data = agaricus.train$data, label = agaricus.train$label, nthread = n_threads
+  )
   cnames <- colnames(dtrain)
   expect_equal(length(cnames), 126)
   tmp_file <- tempfile('xgb.DMatrix_')
@@ -129,7 +135,7 @@ test_that("xgb.DMatrix: saving, loading", {
 })
 
 test_that("xgb.DMatrix: getinfo & setinfo", {
-  dtest <- xgb.DMatrix(test_data)
+  dtest <- xgb.DMatrix(test_data, nthread = n_threads)
   expect_true(setinfo(dtest, 'label', test_label))
   labels <- getinfo(dtest, 'label')
   expect_equal(test_label, getinfo(dtest, 'label'))
@@ -156,7 +162,7 @@ test_that("xgb.DMatrix: getinfo & setinfo", {
 })
 
 test_that("xgb.DMatrix: slice, dim", {
-  dtest <- xgb.DMatrix(test_data, label = test_label)
+  dtest <- xgb.DMatrix(test_data, label = test_label, nthread = n_threads)
   expect_equal(dim(dtest), dim(test_data))
   dsub1 <- slice(dtest, 1:42)
   expect_equal(nrow(dsub1), 42)
@@ -171,16 +177,20 @@ test_that("xgb.DMatrix: slice, trailing empty rows", {
   data(agaricus.train, package = 'xgboost')
   train_data <- agaricus.train$data
   train_label <- agaricus.train$label
-  dtrain <- xgb.DMatrix(data = train_data, label = train_label)
+  dtrain <- xgb.DMatrix(
+    data = train_data, label = train_label, nthread = n_threads
+  )
   slice(dtrain, 6513L)
   train_data[6513, ] <- 0
-  dtrain <- xgb.DMatrix(data = train_data, label = train_label)
+  dtrain <- xgb.DMatrix(
+    data = train_data, label = train_label, nthread = n_threads
+  )
   slice(dtrain, 6513L)
   expect_equal(nrow(dtrain), 6513)
 })
 
 test_that("xgb.DMatrix: colnames", {
-  dtest <- xgb.DMatrix(test_data, label = test_label)
+  dtest <- xgb.DMatrix(test_data, label = test_label, nthread = n_threads)
   expect_equal(colnames(dtest), colnames(test_data))
   expect_error(colnames(dtest) <- 'asdf')
   new_names <- make.names(seq_len(ncol(test_data)))
@@ -196,7 +206,7 @@ test_that("xgb.DMatrix: nrow is correct for a very sparse matrix", {
   x <- Matrix::rsparsematrix(nr, 100, density = 0.0005)
   # we want it very sparse, so that last rows are empty
   expect_lt(max(x@i), nr)
-  dtest <- xgb.DMatrix(x)
+  dtest <- xgb.DMatrix(x, nthread = n_threads)
   expect_equal(dim(dtest), dim(x))
 })
 
@@ -205,8 +215,8 @@ test_that("xgb.DMatrix: print", {
 
     # core DMatrix with just data and labels
     dtrain <- xgb.DMatrix(
-        data = agaricus.train$data
+      data = agaricus.train$data, label = agaricus.train$label,
-        , label = agaricus.train$label
+      nthread = n_threads
     )
     txt <- capture.output({
         print(dtrain)
@@ -222,10 +232,11 @@ test_that("xgb.DMatrix: print", {
 
     # DMatrix with weights and base_margin
     dtrain <- xgb.DMatrix(
-        data = agaricus.train$data
+      data = agaricus.train$data,
-        , label = agaricus.train$label
+      label = agaricus.train$label,
-        , weight = seq_along(agaricus.train$label)
+      weight = seq_along(agaricus.train$label),
-        , base_margin = agaricus.train$label
+      base_margin = agaricus.train$label,
+      nthread = n_threads
     )
     txt <- capture.output({
         print(dtrain)
@@ -234,7 +245,8 @@ test_that("xgb.DMatrix: print", {
 
     # DMatrix with just features
     dtrain <- xgb.DMatrix(
-        data = agaricus.train$data
+      data = agaricus.train$data,
+      nthread = n_threads
     )
     txt <- capture.output({
         print(dtrain)
@@ -245,7 +257,8 @@ test_that("xgb.DMatrix: print", {
     data_no_colnames <- agaricus.train$data
     colnames(data_no_colnames) <- NULL
     dtrain <- xgb.DMatrix(
-        data = data_no_colnames
+      data = data_no_colnames,
+      nthread = n_threads
     )
     txt <- capture.output({
         print(dtrain)

R-package/tests/testthat/test_feature_weights.R

@@ -1,5 +1,7 @@
 context("feature weights")
 
+n_threads <- 2
+
 test_that("training with feature weights works", {
   nrows <- 1000
   ncols <- 9
@@ -10,8 +12,12 @@ test_that("training with feature weights works", {
 
   test <- function(tm) {
     names <- paste0("f", 1:ncols)
-    xy <- xgb.DMatrix(data = x, label = y, feature_weights = weights)
+    xy <- xgb.DMatrix(
-    params <- list(colsample_bynode = 0.4, tree_method = tm, nthread = 1)
+      data = x, label = y, feature_weights = weights, nthread = n_threads
+    )
+    params <- list(
+      colsample_bynode = 0.4, tree_method = tm, nthread = n_threads
+    )
     model <- xgb.train(params = params, data = xy, nrounds = 32)
     importance <- xgb.importance(model = model, feature_names = names)
     expect_equal(dim(importance), c(ncols, 4))

R-package/tests/testthat/test_glm.R

@@ -1,13 +1,19 @@
 context('Test generalized linear models')
 
+n_threads <- 2
+
 test_that("gblinear works", {
   data(agaricus.train, package = 'xgboost')
   data(agaricus.test, package = 'xgboost')
-  dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label)
+  dtrain <- xgb.DMatrix(
-  dtest <- xgb.DMatrix(agaricus.test$data, label = agaricus.test$label)
+    agaricus.train$data, label = agaricus.train$label, nthread = n_threads
+  )
+  dtest <- xgb.DMatrix(
+    agaricus.test$data, label = agaricus.test$label, nthread = n_threads
+  )
 
   param <- list(objective = "binary:logistic", eval_metric = "error", booster = "gblinear",
-                nthread = 2, eta = 0.8, alpha = 0.0001, lambda = 0.0001)
+                nthread = n_threads, eta = 0.8, alpha = 0.0001, lambda = 0.0001)
   watchlist <- list(eval = dtest, train = dtrain)
 
   n <- 5         # iterations
@@ -48,12 +54,16 @@ test_that("gblinear works", {
 test_that("gblinear early stopping works", {
   data(agaricus.train, package = 'xgboost')
   data(agaricus.test, package = 'xgboost')
-  dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label)
+  dtrain <- xgb.DMatrix(
-  dtest <- xgb.DMatrix(agaricus.test$data, label = agaricus.test$label)
+    agaricus.train$data, label = agaricus.train$label, nthread = n_threads
+  )
+  dtest <- xgb.DMatrix(
+    agaricus.test$data, label = agaricus.test$label, nthread = n_threads
+  )
 
   param <- list(
     objective = "binary:logistic", eval_metric = "error", booster = "gblinear",
-    nthread = 2, eta = 0.8, alpha = 0.0001, lambda = 0.0001,
+    nthread = n_threads, eta = 0.8, alpha = 0.0001, lambda = 0.0001,
     updater = "coord_descent"
   )
 

R-package/tests/testthat/test_helpers.R

@@ -171,6 +171,7 @@ test_that("SHAPs sum to predictions, with or without DART", {
     fit <- xgboost(
       params = c(
         list(
+          nthread = 2,
           booster = booster,
           objective = "reg:squarederror",
           eval_metric = "rmse"),
@@ -257,7 +258,7 @@ test_that("xgb.Booster serializing as R object works", {
   .skip_if_vcd_not_available()
   saveRDS(bst.Tree, 'xgb.model.rds')
   bst <- readRDS('xgb.model.rds')
-  dtrain <- xgb.DMatrix(sparse_matrix, label = label)
+  dtrain <- xgb.DMatrix(sparse_matrix, label = label, nthread = 2)
   expect_equal(predict(bst.Tree, dtrain), predict(bst, dtrain), tolerance = float_tolerance)
   expect_equal(xgb.dump(bst.Tree), xgb.dump(bst))
   xgb.save(bst, 'xgb.model')
@@ -363,7 +364,8 @@ test_that("xgb.importance works with and without feature names", {
     data = as.matrix(data.frame(x = c(0, 1))),
     label = c(1, 2),
     nrounds = 1,
-    base_score = 0.5
+    base_score = 0.5,
+    nthread = 2
   )
   df <- xgb.model.dt.tree(model = m)
   expect_equal(df$Feature, "Leaf")

R-package/tests/testthat/test_interaction_constraints.R

@@ -2,6 +2,8 @@ require(xgboost)
 
 context("interaction constraints")
 
+n_threads <- 2
+
 set.seed(1024)
 x1 <- rnorm(1000, 1)
 x2 <- rnorm(1000, 1)
@@ -45,11 +47,18 @@ test_that("interaction constraints scientific representation", {
   d <- matrix(rexp(rows, rate = .1), nrow = rows, ncol = cols)
   y <- rnorm(rows)
 
-  dtrain <- xgb.DMatrix(data = d, info = list(label = y))
+  dtrain <- xgb.DMatrix(data = d, info = list(label = y), nthread = n_threads)
   inc <- list(c(seq.int(from = 0, to = cols, by = 1)))
 
-  with_inc <- xgb.train(data = dtrain, tree_method = 'hist',
+  with_inc <- xgb.train(
-                        interaction_constraints = inc, nrounds = 10)
+    data = dtrain,
-  without_inc <- xgb.train(data = dtrain, tree_method = 'hist', nrounds = 10)
+    tree_method = 'hist',
+    interaction_constraints = inc,
+    nrounds = 10,
+    nthread = n_threads
+  )
+  without_inc <- xgb.train(
+    data = dtrain, tree_method = 'hist', nrounds = 10, nthread = n_threads
+  )
   expect_equal(xgb.save.raw(with_inc), xgb.save.raw(without_inc))
 })

R-package/tests/testthat/test_interactions.R

@@ -1,6 +1,7 @@
 context('Test prediction of feature interactions')
 
 set.seed(123)
+n_threads <- 2
 
 test_that("predict feature interactions works", {
   # simulate some binary data and a linear outcome with an interaction term
@@ -19,8 +20,10 @@ test_that("predict feature interactions works", {
 
   y <- f_int(X)
 
-  dm <- xgb.DMatrix(X, label = y)
+  dm <- xgb.DMatrix(X, label = y, nthread = n_threads)
-  param <- list(eta = 0.1, max_depth = 4, base_score = mean(y), lambda = 0, nthread = 2)
+  param <- list(
+    eta = 0.1, max_depth = 4, base_score = mean(y), lambda = 0, nthread = n_threads
+  )
   b <- xgb.train(param, dm, 100)
 
   pred <- predict(b, dm, outputmargin = TRUE)
@@ -99,11 +102,13 @@ test_that("SHAP contribution values are not NAN", {
     verbose = 0,
     params = list(
       objective = "reg:squarederror",
-      eval_metric = "rmse"),
+      eval_metric = "rmse",
+      nthread = n_threads
+    ),
     data = as.matrix(subset(d, fold == 2)[, ivs]),
     label = subset(d, fold == 2)$y,
-    nthread = 1,
+    nrounds = 3
-    nrounds = 3)
+  )
 
   shaps <- as.data.frame(predict(fit,
     newdata = as.matrix(subset(d, fold == 1)[, ivs]),
@@ -116,8 +121,12 @@ test_that("SHAP contribution values are not NAN", {
 
 
 test_that("multiclass feature interactions work", {
-  dm <- xgb.DMatrix(as.matrix(iris[, -5]), label = as.numeric(iris$Species) - 1)
+  dm <- xgb.DMatrix(
-  param <- list(eta = 0.1, max_depth = 4, objective = 'multi:softprob', num_class = 3)
+    as.matrix(iris[, -5]), label = as.numeric(iris$Species) - 1, nthread = n_threads
+  )
+  param <- list(
+    eta = 0.1, max_depth = 4, objective = 'multi:softprob', num_class = 3, nthread = n_threads
+  )
   b <- xgb.train(param, dm, 40)
   pred <- t(
     array(
@@ -166,6 +175,7 @@ test_that("SHAP single sample works", {
     max_depth = 2,
     nrounds = 4,
     objective = "binary:logistic",
+    nthread = n_threads
   )
 
   predt <- predict(

R-package/tests/testthat/test_io.R

@@ -9,7 +9,8 @@ test_that("load/save raw works", {
   nrounds <- 8
   booster <- xgboost(
     data = train$data, label = train$label,
-    nrounds = nrounds, objective = "binary:logistic"
+    nrounds = nrounds, objective = "binary:logistic",
+    nthread = 2
   )
 
   json_bytes <- xgb.save.raw(booster, raw_format = "json")

R-package/tests/testthat/test_model_compatibility.R

@@ -66,7 +66,7 @@ test_that("Models from previous versions of XGBoost can be loaded", {
   unzip(zipfile, exdir = extract_dir, overwrite = TRUE)
   model_dir <- file.path(extract_dir, 'models')
 
-  pred_data <- xgb.DMatrix(matrix(c(0, 0, 0, 0), nrow = 1, ncol = 4))
+  pred_data <- xgb.DMatrix(matrix(c(0, 0, 0, 0), nrow = 1, ncol = 4), nthread = 2)
 
   lapply(list.files(model_dir), function (x) {
     model_file <- file.path(model_dir, x)
@@ -87,6 +87,7 @@ test_that("Models from previous versions of XGBoost can be loaded", {
         booster <- readRDS(model_file)
       } else {
         booster <- xgb.load(model_file)
+        xgb.parameters(booster) <- list(nthread = 2)
       }
       predict(booster, newdata = pred_data)
       run_booster_check(booster, name)

R-package/tests/testthat/test_parameter_exposure.R

@@ -3,8 +3,12 @@ context('Test model params and call are exposed to R')
 data(agaricus.train, package = 'xgboost')
 data(agaricus.test, package = 'xgboost')
 
-dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label)
+dtrain <- xgb.DMatrix(
-dtest <- xgb.DMatrix(agaricus.test$data, label = agaricus.test$label)
+  agaricus.train$data, label = agaricus.train$label, nthread = 2
+)
+dtest <- xgb.DMatrix(
+  agaricus.test$data, label = agaricus.test$label, nthread = 2
+)
 
 bst <- xgboost(data = dtrain,
                max_depth = 2,

R-package/tests/testthat/test_poisson_regression.R

@@ -4,8 +4,10 @@ set.seed(1994)
 
 test_that("Poisson regression works", {
   data(mtcars)
-  bst <- xgboost(data = as.matrix(mtcars[, -11]), label = mtcars[, 11],
+  bst <- xgboost(
-                objective = 'count:poisson', nrounds = 10, verbose = 0)
+    data = as.matrix(mtcars[, -11]), label = mtcars[, 11],
+    objective = 'count:poisson', nrounds = 10, verbose = 0, nthread = 2
+  )
   expect_equal(class(bst), "xgb.Booster")
   pred <- predict(bst, as.matrix(mtcars[, -11]))
   expect_equal(length(pred), 32)

R-package/tests/testthat/test_ranking.R

@@ -1,5 +1,7 @@
 context('Learning to rank')
 
+n_threads <- 2
+
 test_that('Test ranking with unweighted data', {
   X <- Matrix::sparseMatrix(
     i = c(2, 3, 7, 9, 12, 15, 17, 18)
@@ -9,10 +11,10 @@ test_that('Test ranking with unweighted data', {
   )
   y <- c(0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0)
   group <- c(5, 5, 5, 5)
-  dtrain <- xgb.DMatrix(X, label = y, group = group)
+  dtrain <- xgb.DMatrix(X, label = y, group = group, nthread = n_threads)
 
   params <- list(eta = 1, tree_method = 'exact', objective = 'rank:pairwise', max_depth = 1,
-                 eval_metric = 'auc', eval_metric = 'aucpr')
+                 eval_metric = 'auc', eval_metric = 'aucpr', nthread = n_threads)
   bst <- xgb.train(params, dtrain, nrounds = 10, watchlist = list(train = dtrain))
   # Check if the metric is monotone increasing
   expect_true(all(diff(bst$evaluation_log$train_auc) >= 0))
@@ -29,10 +31,14 @@ test_that('Test ranking with weighted data', {
   y <- c(0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0)
   group <- c(5, 5, 5, 5)
   weight <- c(1.0, 2.0, 3.0, 4.0)
-  dtrain <- xgb.DMatrix(X, label = y, group = group, weight = weight)
+  dtrain <- xgb.DMatrix(
+    X, label = y, group = group, weight = weight, nthread = n_threads
+  )
 
-  params <- list(eta = 1, tree_method = 'exact', objective = 'rank:pairwise', max_depth = 1,
+  params <- list(
-                 eval_metric = 'auc', eval_metric = 'aucpr')
+    eta = 1, tree_method = "exact", objective = "rank:pairwise", max_depth = 1,
+    eval_metric = "auc", eval_metric = "aucpr", nthread = n_threads
+  )
   bst <- xgb.train(params, dtrain, nrounds = 10, watchlist = list(train = dtrain))
   # Check if the metric is monotone increasing
   expect_true(all(diff(bst$evaluation_log$train_auc) >= 0))

R-package/tests/testthat/test_unicode.R

@@ -16,6 +16,7 @@ test_that("Can save and load models with Unicode paths", {
     path <- file.path(tmpdir, x)
     xgb.save(bst, path)
     bst2 <- xgb.load(path)
+    xgb.parameters(bst2) <- list(nthread = 2)
     expect_equal(predict(bst, test$data), predict(bst2, test$data))
   })
 })

R-package/tests/testthat/test_update.R

@@ -2,8 +2,15 @@ context("update trees in an existing model")
 
 data(agaricus.train, package = 'xgboost')
 data(agaricus.test, package = 'xgboost')
-dtrain <- xgb.DMatrix(agaricus.train$data, label = agaricus.train$label)
+
-dtest <- xgb.DMatrix(agaricus.test$data, label = agaricus.test$label)
+n_threads <- 1
+
+dtrain <- xgb.DMatrix(
+  agaricus.train$data, label = agaricus.train$label, nthread = n_threads
+)
+dtest <- xgb.DMatrix(
+  agaricus.test$data, label = agaricus.test$label, nthread = n_threads
+)
 
 # Disable flaky tests for 32-bit Windows.
 # See https://github.com/dmlc/xgboost/issues/3720
@@ -14,7 +21,7 @@ test_that("updating the model works", {
 
   # no-subsampling
   p1 <- list(
-    objective = "binary:logistic", max_depth = 2, eta = 0.05, nthread = 2,
+    objective = "binary:logistic", max_depth = 2, eta = 0.05, nthread = n_threads,
     updater = "grow_colmaker,prune"
   )
   set.seed(11)
@@ -86,9 +93,11 @@ test_that("updating the model works", {
 })
 
 test_that("updating works for multiclass & multitree", {
-  dtr <- xgb.DMatrix(as.matrix(iris[, -5]), label = as.numeric(iris$Species) - 1)
+  dtr <- xgb.DMatrix(
+    as.matrix(iris[, -5]), label = as.numeric(iris$Species) - 1, nthread = n_threads
+  )
   watchlist <- list(train = dtr)
-  p0 <- list(max_depth = 2, eta = 0.5, nthread = 2, subsample = 0.6,
+  p0 <- list(max_depth = 2, eta = 0.5, nthread = n_threads, subsample = 0.6,
              objective = "multi:softprob", num_class = 3, num_parallel_tree = 2,
              base_score = 0)
   set.seed(121)

R-package/vignettes/discoverYourData.Rmd

@@ -31,6 +31,8 @@ require(data.table)
 if (!require('vcd')) {
   install.packages('vcd')
 }
+
+data.table::setDTthreads(2)
 ```
 
 > **VCD** package is used for one of its embedded dataset only.
@@ -297,23 +299,25 @@ test <- agaricus.test
 
 #Random Forest - 1000 trees
 bst <- xgboost(
-    data = train$data
+    data = train$data,
-    , label = train$label
+    label = train$label,
-    , max_depth = 4
+    max_depth = 4,
-    , num_parallel_tree = 1000
+    num_parallel_tree = 1000,
-    , subsample = 0.5
+    subsample = 0.5,
-    , colsample_bytree = 0.5
+    colsample_bytree = 0.5,
-    , nrounds = 1
+    nrounds = 1,
-    , objective = "binary:logistic"
+    objective = "binary:logistic",
+    nthread = 2
 )
 
 #Boosting - 3 rounds
 bst <- xgboost(
-    data = train$data
+    data = train$data,
-    , label = train$label
+    label = train$label,
-    , max_depth = 4
+    max_depth = 4,
-    , nrounds = 3
+    nrounds = 3,
-    , objective = "binary:logistic"
+    objective = "binary:logistic",
+    nthread = 2
 )
 ```
 

R-package/vignettes/xgboost.Rnw

@@ -86,9 +86,10 @@ data(agaricus.test, package='xgboost')
 train <- agaricus.train
 test <- agaricus.test
 bst <- xgboost(data = train$data, label = train$label, max_depth = 2, eta = 1,
-               nrounds = 2, objective = "binary:logistic")
+               nrounds = 2, objective = "binary:logistic", nthread = 2)
 xgb.save(bst, 'model.save')
 bst = xgb.load('model.save')
+xgb.parameters(bst) <- list(nthread = 2)
 pred <- predict(bst, test$data)
 @
 
@@ -127,7 +128,7 @@ training from initial prediction value, weighted training instance.
 
 We can use \verb@xgb.DMatrix@ to construct an \verb@xgb.DMatrix@ object:
 <<xgb.DMatrix>>=
-dtrain <- xgb.DMatrix(train$data, label = train$label)
+dtrain <- xgb.DMatrix(train$data, label = train$label, nthread = 2)
 class(dtrain)
 head(getinfo(dtrain,'label'))
 @
@@ -161,9 +162,9 @@ evalerror <- function(preds, dtrain) {
   return(list(metric = "MSE", value = err))
 }
 
-dtest <- xgb.DMatrix(test$data, label = test$label)
+dtest <- xgb.DMatrix(test$data, label = test$label, nthread = 2)
 watchlist <- list(eval = dtest, train = dtrain)
-param <- list(max_depth = 2, eta = 1)
+param <- list(max_depth = 2, eta = 1, nthread = 2)
 
 bst <- xgb.train(param, dtrain, nrounds = 2, watchlist, logregobj, evalerror, maximize = FALSE)
 @

R-package/vignettes/xgboostPresentation.Rmd

@@ -173,13 +173,13 @@ Alternatively, you can put your dataset in a *dense* matrix, i.e. a basic **R**
 
 ```{r trainingDense, message=F, warning=F}
 bstDense <- xgboost(
-    data = as.matrix(train$data)
+    data = as.matrix(train$data),
-    , label = train$label
+    label = train$label,
-    , max_depth = 2
+    max_depth = 2,
-    , eta = 1
+    eta = 1,
-    , nthread = 2
+    nthread = 2,
-    , nrounds = 2
+    nrounds = 2,
-    , objective = "binary:logistic"
+    objective = "binary:logistic"
 )
 ```
 
@@ -188,14 +188,14 @@ bstDense <- xgboost(
 **XGBoost** offers a way to group them in a `xgb.DMatrix`. You can even add other meta data in it. It will be useful for the most advanced features we will discover later.
 
 ```{r trainingDmatrix, message=F, warning=F}
-dtrain <- xgb.DMatrix(data = train$data, label = train$label)
+dtrain <- xgb.DMatrix(data = train$data, label = train$label, nthread = 2)
 bstDMatrix <- xgboost(
-    data = dtrain
+    data = dtrain,
-    , max_depth = 2
+    max_depth = 2,
-    , eta = 1
+    eta = 1,
-    , nthread = 2
+    nthread = 2,
-    , nrounds = 2
+    nrounds = 2,
-    , objective = "binary:logistic"
+    objective = "binary:logistic"
 )
 ```
 
@@ -314,8 +314,8 @@ Most of the features below have been implemented to help you to improve your mod
 For the following advanced features, we need to put data in `xgb.DMatrix` as explained above.
 
 ```{r DMatrix, message=F, warning=F}
-dtrain <- xgb.DMatrix(data = train$data, label = train$label)
+dtrain <- xgb.DMatrix(data = train$data, label = train$label, nthread = 2)
-dtest <- xgb.DMatrix(data = test$data, label = test$label)
+dtest <- xgb.DMatrix(data = test$data, label = test$label, nthread = 2)
 ```
 
 ### Measure learning progress with xgb.train
@@ -476,6 +476,7 @@ An interesting test to see how identical our saved model is to the original one
 ```{r loadModel, message=F, warning=F}
 # load binary model to R
 bst2 <- xgb.load("xgboost.model")
+xgb.parameters(bst2) <- list(nthread = 2)
 pred2 <- predict(bst2, test$data)
 
 # And now the test
@@ -500,6 +501,7 @@ print(class(rawVec))
 
 # load binary model to R
 bst3 <- xgb.load(rawVec)
+xgb.parameters(bst3) <- list(nthread = 2)
 pred3 <- predict(bst3, test$data)
 
 # pred2 should be identical to pred

doc/contrib/coding_guide.rst

@@ -80,6 +80,24 @@ R package versioning
 ====================
 See :ref:`release`.
 
+Testing R package with different compilers
+==========================================
+
+You can change the default compiler of R by changing the configuration file in home
+directory. For instance, if you want to test XGBoost built with clang++ instead of g++ on
+Linux, put the following in your ``~/.R/Makevars`` file:
+
+.. code-block:: sh
+
+  CC=clang-15
+  CXX17=clang++-15
+
+Be aware that the variable name should match with the name used by ``R CMD``:
+
+.. code-block:: sh
+
+  R CMD config CXX17
+
 Registering native routines in R
 ================================
 According to `R extension manual <https://cran.r-project.org/doc/manuals/r-release/R-exts.html#Registering-native-routines>`_,

src/data/ellpack_page_source.h

@@ -50,6 +50,7 @@ inline void EllpackPageSource::Fetch() {
   // silent the warning about unused variables.
   (void)(row_stride_);
   (void)(is_dense_);
+  (void)(device_);
   common::AssertGPUSupport();
 }
 #endif  // !defined(XGBOOST_USE_CUDA)

src/gbm/gbtree_model.cc

@@ -106,14 +106,30 @@ void GBTreeModel::Load(dmlc::Stream* fi) {
   Validate(*this);
 }
 
+namespace {
+std::int32_t IOThreads(Context const* ctx) {
+  CHECK(ctx);
+  std::int32_t n_threads = ctx->Threads();
+  // CRAN checks for number of threads used by examples, but we might not have the right
+  // number of threads when serializing/unserializing models as nthread is a booster
+  // parameter, which is only effective after booster initialization.
+  //
+  // The threshold ratio of CPU time to user time for R is 2.5, we set the number of
+  // threads to 2.
+#if defined(XGBOOST_STRICT_R_MODE) && XGBOOST_STRICT_R_MODE == 1
+  n_threads = std::min(2, n_threads);
+#endif
+  return n_threads;
+}
+}  // namespace
+
 void GBTreeModel::SaveModel(Json* p_out) const {
   auto& out = *p_out;
   CHECK_EQ(param.num_trees, static_cast<int>(trees.size()));
   out["gbtree_model_param"] = ToJson(param);
   std::vector<Json> trees_json(trees.size());
 
-  CHECK(ctx_);
+  common::ParallelFor(trees.size(), IOThreads(ctx_), [&](auto t) {
-  common::ParallelFor(trees.size(), ctx_->Threads(), [&](auto t) {
     auto const& tree = trees[t];
     Json jtree{Object{}};
     tree->SaveModel(&jtree);
@@ -151,9 +167,7 @@ void GBTreeModel::LoadModel(Json const& in) {
   CHECK_EQ(tree_info_json.size(), param.num_trees);
   tree_info.resize(param.num_trees);
 
-  CHECK(ctx_);
+  common::ParallelFor(param.num_trees, IOThreads(ctx_), [&](auto t) {
-
-  common::ParallelFor(param.num_trees, ctx_->Threads(), [&](auto t) {
     auto tree_id = get<Integer const>(trees_json[t]["id"]);
     trees.at(tree_id).reset(new RegTree{});
     trees[tree_id]->LoadModel(trees_json[t]);

tests/ci_build/test_r_package.py

@@ -3,9 +3,15 @@ import argparse
 import os
 import shutil
 import subprocess
+from io import StringIO
 from pathlib import Path
 from platform import system
 
+try:
+    import pandas as pd
+except ImportError:
+    pd = None
+
 from test_utils import R_PACKAGE, ROOT, DirectoryExcursion, cd, print_time, record_time
 
 
@@ -97,16 +103,47 @@ def build_rpackage(path: str) -> str:
     return tarball
 
 
+def check_example_timing(rcheck_dir: Path, threshold: float) -> None:
+    with open(rcheck_dir / "xgboost-Ex.timings", "r") as fd:
+        timings = fd.readlines()
+        newlines = []
+        for line in timings:
+            line = line.strip()
+            newlines.append(line)
+        con_timings = "\n".join(newlines)
+        df = pd.read_csv(StringIO(con_timings), delimiter="\t")
+        ratio_n = "user/elapsed"
+        df[ratio_n] = df["user"] / df["elapsed"]
+        offending = df[df[ratio_n] > threshold]
+
+    try:
+        # requires the tabulate package
+        df.to_markdown("timings.md")
+        offending.to_markdown("offending.md")
+    except ImportError:
+        print("failed to export markdown files.")
+        pass
+
+    if offending.shape[0] == 0:
+        return
+
+    print(offending)
+    raise ValueError("There are examples using too many threads")
+
+
 @cd(ROOT)
 @record_time
 def check_rpackage(path: str) -> None:
     env = os.environ.copy()
     print("Ncpus:", f"{os.cpu_count()}")
+    threshold = 2.5
     env.update(
         {
             "MAKEFLAGS": f"-j{os.cpu_count()}",
             # cran specific environment variables
-            "_R_CHECK_EXAMPLE_TIMING_CPU_TO_ELAPSED_THRESHOLD_": str(2.5),
+            "_R_CHECK_EXAMPLE_TIMING_CPU_TO_ELAPSED_THRESHOLD_": str(threshold),
+            "_R_CHECK_TEST_TIMING_CPU_TO_ELAPSED_THRESHOLD_": str(threshold),
+            "_R_CHECK_VIGNETTE_TIMING_CPU_TO_ELAPSED_THRESHOLD_": str(threshold),
         }
     )
 
@@ -118,11 +155,14 @@ def check_rpackage(path: str) -> None:
         CC = os.path.join(mingw_bin, "gcc.exe")
         env.update({"CC": CC, "CXX": CXX})
 
-    status = subprocess.run([R, "CMD", "check", "--as-cran", path], env=env)
+    status = subprocess.run(
-    with open(Path("xgboost.Rcheck") / "00check.log", "r") as fd:
+        [R, "CMD", "check", "--as-cran", "--timings", path], env=env
+    )
+    rcheck_dir = Path("xgboost.Rcheck")
+    with open(rcheck_dir / "00check.log", "r") as fd:
         check_log = fd.read()
 
-    with open(Path("xgboost.Rcheck") / "00install.out", "r") as fd:
+    with open(rcheck_dir / "00install.out", "r") as fd:
         install_log = fd.read()
 
     msg = f"""
@@ -144,6 +184,8 @@ def check_rpackage(path: str) -> None:
     if check_log.find("Examples with CPU time") != -1:
         print(msg)
         raise ValueError("Suspicious NOTE.")
+    if pd is not None:
+        check_example_timing(rcheck_dir, threshold)
 
 
 @cd(R_PACKAGE)
@@ -264,6 +306,8 @@ def main(args: argparse.Namespace) -> None:
             test_with_autotools()
         else:
             test_with_cmake(args)
+    elif args.task == "timings":
+        check_example_timing(Path("xgboost.Rcheck"), 2.5)
     else:
         raise ValueError("Unexpected task.")
 
@@ -279,7 +323,7 @@ if __name__ == "__main__":
     parser.add_argument(
         "--task",
         type=str,
-        choices=["pack", "build", "check", "doc"],
+        choices=["pack", "build", "check", "doc", "timings"],
         default="check",
         required=False,
     )