[pyspark] Reuse the collective communicator.

python-package/xgboost/spark/utils.py

@@ -14,7 +14,8 @@
 from pyspark import BarrierTaskContext, SparkConf, SparkContext, SparkFiles, TaskContext
 from pyspark.sql.session import SparkSession
 
-from xgboost import Booster, XGBModel, collective
+from xgboost import Booster, XGBModel
+from xgboost.collective import CommunicatorContext as CCtx
 from xgboost.tracker import RabitTracker
 
 
@@ -42,22 +43,12 @@ def _get_default_params_from_func(
     return filtered_params_dict
 
 
-class CommunicatorContext:
-    """A context controlling collective communicator initialization and finalization.
-    This isn't specificially necessary (note Part 3), but it is more understandable
-    coding-wise.
-
-    """
+class CommunicatorContext(CCtx):  # pylint: disable=too-few-public-methods
+    """Context with PySpark specific task ID."""
 
     def __init__(self, context: BarrierTaskContext, **args: Any) -> None:
-        self.args = args
-        self.args["DMLC_TASK_ID"] = str(context.partitionId())
-
-    def __enter__(self) -> None:
-        collective.init(**self.args)
-
-    def __exit__(self, *args: Any) -> None:
-        collective.finalize()
+        args["DMLC_TASK_ID"] = str(context.partitionId())
+        super().__init__(**args)
 
 
 def _start_tracker(context: BarrierTaskContext, n_workers: int) -> Dict[str, Any]: