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https://issues.apache.org/jira/browse/SPARK-25921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16672350#comment-16672350
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Xiangrui Meng commented on SPARK-25921:
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Tested offline. This was caused by PySpark worker reuse. A workaround is to
disable worker reuse. Not a blocker for 2.4, but we should list it as a known
issue and fix it in 2.4.1. cc: [~cloud_fan] [~smilegator]
> Python worker reuse causes Barrier tasks to run without BarrierTaskContext
> --------------------------------------------------------------------------
>
> Key: SPARK-25921
> URL: https://issues.apache.org/jira/browse/SPARK-25921
> Project: Spark
> Issue Type: Bug
> Components: PySpark, Spark Core
> Affects Versions: 2.4.0
> Reporter: Bago Amirbekian
> Priority: Critical
>
> Running a barrier job after a normal spark job causes the barrier job to run
> without a BarrierTaskContext. Here is some code to reproduce.
>
> {code:java}
> def task(*args):
> from pyspark import BarrierTaskContext
> context = BarrierTaskContext.get()
> context.barrier()
> print("in barrier phase")
> context.barrier()
> return []
> a = sc.parallelize(list(range(4))).map(lambda x: x ** 2).collect()
> assert a == [0, 1, 4, 9]
> b = sc.parallelize(list(range(4)), 4).barrier().mapPartitions(task).collect()
> {code}
>
> Here is some of the trace
> {code:java}
> Py4JJavaError: An error occurred while calling
> z:org.apache.spark.api.python.PythonRDD.collectAndServe.
> : org.apache.spark.SparkException: Job aborted due to stage failure: Could
> not recover from a failed barrier ResultStage. Most recent failure reason:
> Stage failed because barrier task ResultTask(14, 0) finished unsuccessfully.
> org.apache.spark.api.python.PythonException: Traceback (most recent call
> last):
> File "/databricks/spark/python/pyspark/worker.py", line 372, in main
> process()
> File "/databricks/spark/python/pyspark/worker.py", line 367, in process
> serializer.dump_stream(func(split_index, iterator), outfile)
> File "/databricks/spark/python/pyspark/rdd.py", line 2482, in func
> return f(iterator)
> File "<command-717066991496742>", line 4, in task
> AttributeError: 'TaskContext' object has no attribute 'barrier'
> {code}
>
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