* [jvm-packages] fix executor crashing issue when transforming on xgboost4j-spark-gpu
the API XGBoosterSetParam is not thread-safe. Dring the phase of transforming,
XGBoost runs several transforming tasks at a time, and each of them will set
the "gpu_id" and "predictor" parameters, so if several tasks (multi-threads)
all XGBoosterSetParam simultaneously, it may cause the memory to be corrupted
and cause SIGSEGV.
This PR first get the booster from broadcast and set to the correct gpu_id
and predictor, and then all transforming taskes will use the same booster to
do the transforming.
This PR removes auto-detection of MUSL-based Linux systems in favor of system properties the user can set to configure a specific path for a native library.
With the introduction of the barrier execution mode. we don't need to kill SparkContext when some xgboost tasks failed. Instead, Spark will handle the errors for us. So in this PR, `killSparkContextOnWorkerFailure` parameter is deleted.
xgboost4j-spark provides 2 sets of API for setting features, one for CPU, another for GPU, which may cause confusion.
This PR removes the GPU API and adds an override CPU function setFeaturesCol to accept Array[String] parameters.
This PR rewrites the approx tree method to use codebase from hist for better performance and code sharing.
The rewrite has many benefits:
- Support for both `max_leaves` and `max_depth`.
- Support for `grow_policy`.
- Support for mono constraint.
- Support for feature weights.
- Support for easier bin configuration (`max_bin`).
- Support for categorical data.
- Faster performance for most of the datasets. (many times faster)
- Support for prediction cache.
- Significantly better performance for external memory.
- Unites the code base between approx and hist.
* Extend array interface to handle ndarray.
The `ArrayInterface` class is extended to support multi-dim array inputs. Previously this
class handles only 2-dim (vector is also matrix). This PR specifies the expected
dimension at compile-time and the array interface can perform various checks automatically
for input data. Also, adapters like CSR are more rigorous about their input. Lastly, row
vector and column vector are handled without intervention from the caller.
Spark 3.2 depends on 3.7.0-M11 which has changed some implicited functions'
signatures. And it will result the xgboost4j built against spark 3.0/3.1
failed when saving the model.
Following classes are added to support dataframe in java binding:
- `Column` is an abstract type for a single column in tabular data.
- `ColumnBatch` is an abstract type for dataframe.
- `CuDFColumn` is an implementaiton of `Column` that consume cuDF column
- `CudfColumnBatch` is an implementation of `ColumnBatch` that consumes cuDF dataframe.
- `DeviceQuantileDMatrix` is the interface for quantized data.
The Java implementation mimics the Python interface and uses `__cuda_array_interface__` protocol for memory indexing. One difference is on JVM package, the data batch is staged on the host as java iterators cannot be reset.
Co-authored-by: jiamingy <jm.yuan@outlook.com>
