Fix pyspark parameter. (#9460)

- Don't pass the `use_gpu` parameter to the learner.
- Fix GPU approx with PySpark.

python-package/xgboost/spark/core.py

@@ -115,6 +115,7 @@ _pyspark_specific_params = [
     "qid_col",
     "repartition_random_shuffle",
     "pred_contrib_col",
+    "use_gpu",
 ]
 
 _non_booster_params = ["missing", "n_estimators", "feature_types", "feature_weights"]
@@ -349,11 +350,9 @@ class _SparkXGBParams(
             )
 
         tree_method = self.getOrDefault(self.getParam("tree_method"))
-        if (
-            self.getOrDefault(self.use_gpu) or use_cuda(self.getOrDefault(self.device))
-        ) and not _can_use_qdm(tree_method):
+        if tree_method == "exact":
             raise ValueError(
-                f"The `{tree_method}` tree method is not supported on GPU."
+                "The `exact` tree method is not supported for distributed systems."
             )
 
         if self.getOrDefault(self.features_cols):

tests/test_distributed/test_gpu_with_spark/test_gpu_spark.py

@@ -151,12 +151,18 @@ def spark_diabetes_dataset_feature_cols(spark_session_with_gpu):
     return train_df, test_df, data.feature_names
 
 
-def test_sparkxgb_classifier_with_gpu(spark_iris_dataset):
+@pytest.mark.parametrize("tree_method", ["hist", "approx"])
+def test_sparkxgb_classifier_with_gpu(tree_method: str, spark_iris_dataset) -> None:
     from pyspark.ml.evaluation import MulticlassClassificationEvaluator
 
-    classifier = SparkXGBClassifier(device="cuda", num_workers=num_workers)
+    classifier = SparkXGBClassifier(
+        device="cuda", num_workers=num_workers, tree_method=tree_method
+    )
     train_df, test_df = spark_iris_dataset
     model = classifier.fit(train_df)
+    config = json.loads(model.get_booster().save_config())
+    ctx = config["learner"]["generic_param"]
+    assert ctx["device"] == "cuda:0"
     pred_result_df = model.transform(test_df)
     evaluator = MulticlassClassificationEvaluator(metricName="f1")
     f1 = evaluator.evaluate(pred_result_df)

tests/test_distributed/test_with_spark/test_spark_local.py

@@ -456,7 +456,9 @@ def check_sub_dict_match(
             assert sub_dist[k] == whole_dict[k], f"check on {k} failed"
 
 
-def get_params_map(params_kv: dict, estimator: Type) -> dict:
+def get_params_map(
+    params_kv: dict, estimator: xgb.spark.core._SparkXGBEstimator
+) -> dict:
     return {getattr(estimator, k): v for k, v in params_kv.items()}
 
 
@@ -870,10 +872,10 @@ class TestPySparkLocal:
 
     def test_device_param(self, reg_data: RegData, clf_data: ClfData) -> None:
         clf = SparkXGBClassifier(device="cuda", tree_method="exact")
-        with pytest.raises(ValueError, match="not supported on GPU"):
+        with pytest.raises(ValueError, match="not supported for distributed"):
             clf.fit(clf_data.cls_df_train)
         regressor = SparkXGBRegressor(device="cuda", tree_method="exact")
-        with pytest.raises(ValueError, match="not supported on GPU"):
+        with pytest.raises(ValueError, match="not supported for distributed"):
             regressor.fit(reg_data.reg_df_train)
 
         reg = SparkXGBRegressor(device="cuda", tree_method="gpu_hist")