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
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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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