[GitHub] [spark] ConeyLiu commented on a change in pull request #26239: [SPARK-29582][PYSPARK] Unify the behavior of pyspark.TaskContext with spark core

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ConeyLiu commented on a change in pull request #26239: [SPARK-29582][PYSPARK] Unify the behavior of pyspark.TaskContext with spark core
URL: https://github.com/apache/spark/pull/26239#discussion_r338857363
 
 

 ##########
 File path: python/pyspark/tests/test_taskcontext.py
 ##########
 @@ -181,6 +224,40 @@ def context_barrier(x):
         for pid in pids:
             self.assertTrue(pid in worker_pids)
 
+    def test_task_context_correct_with_python_worker_reuse(self):
+        """Verify the task context correct when reused python worker"""
+        # start a normal job first to start all workers and get all worker pids
+        worker_pids = self.sc.parallelize(range(2), 2).map(lambda x: os.getpid()).collect()
+        # the worker will reuse in this barrier job
+        rdd = self.sc.parallelize(range(10), 2)
+
+        def context(iterator):
+            tp = TaskContext.get().partitionId()
+            try:
+                bp = BarrierTaskContext.get().partitionId()
+            except RuntimeError:
+                bp = -1
+
+            yield (tp, bp, os.getpid())
+
+        def verify(result, task_context_target, barrier_context_target):
+            tps = list(map(lambda x: x[0], result))
+            bps = list(map(lambda x: x[1], result))
+            pids = list(map(lambda x: x[2], result))
+            self.assertTrue(tps == task_context_target)
+            self.assertTrue(bps == barrier_context_target)
+            for pid in pids:
+                self.assertTrue(pid in worker_pids)
+        # normal stage after normal stage
+        normal_result = rdd.mapPartitions(context).collect()
+        verify(normal_result, [0, 1], [-1, -1])
+        # barrier stage after normal stage
+        barrier_result = rdd.barrier().mapPartitions(context).collect()
 
 Review comment:
   I have passed tests in python3.6. However, it failed in python2.7. It seems that the python workers aren't reused even the config is set in python2.7.
   I tested here with:
   ```python
   normal_result = rdd.mapPartitions(lambda x: x).collect()
   verify(normal_result, [0, 1], [-1, -1])   # it passed
   
   normal_result = rdd.mapPartitions(lambda x: x).collect()
   normal_result = rdd.mapPartitions(lambda x: x).collect()
   normal_result = rdd.mapPartitions(lambda x: x).collect()
   verify(normal_result, [0, 1], [-1, -1])   # it failed with pids have changed
   ``` 
   
   Hi @srowen, would you know some background about this? Thanks a lot.

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