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https://issues.apache.org/jira/browse/SPARK-26776?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16755602#comment-16755602
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Apache Spark commented on SPARK-26776:
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User 'HyukjinKwon' has created a pull request for this issue:
https://github.com/apache/spark/pull/23690
> Reduce Py4J communication cost in PySpark's execution barrier check
> -------------------------------------------------------------------
>
> Key: SPARK-26776
> URL: https://issues.apache.org/jira/browse/SPARK-26776
> Project: Spark
> Issue Type: Bug
> Components: PySpark
> Affects Versions: 2.4.0, 3.0.0
> Reporter: Hyukjin Kwon
> Priority: Minor
>
> I am investigating flaky tests. I realised that:
> {code}
> File
> "/home/jenkins/workspace/SparkPullRequestBuilder/python/pyspark/rdd.py", line
> 2512, in __init__
> self.is_barrier = prev._is_barrier() or isFromBarrier
> File
> "/home/jenkins/workspace/SparkPullRequestBuilder/python/pyspark/rdd.py", line
> 2412, in _is_barrier
> return self._jrdd.rdd().isBarrier()
> File
> "/home/jenkins/workspace/SparkPullRequestBuilder/python/lib/py4j-0.10.8.1-src.zip/py4j/java_gateway.py",
> line 1286, in __call__
> answer, self.gateway_client, self.target_id, self.name)
> File
> "/home/jenkins/workspace/SparkPullRequestBuilder/python/lib/py4j-0.10.8.1-src.zip/py4j/protocol.py",
> line 342, in get_return_value
> return OUTPUT_CONVERTER[type](answer[2:], gateway_client)
> File
> "/home/jenkins/workspace/SparkPullRequestBuilder/python/lib/py4j-0.10.8.1-src.zip/py4j/java_gateway.py",
> line 2492, in <lambda>
> lambda target_id, gateway_client: JavaObject(target_id,
> gateway_client))
> File
> "/home/jenkins/workspace/SparkPullRequestBuilder/python/lib/py4j-0.10.8.1-src.zip/py4j/java_gateway.py",
> line 1324, in __init__
> ThreadSafeFinalizer.add_finalizer(key, value)
> File
> "/home/jenkins/workspace/SparkPullRequestBuilder/python/lib/py4j-0.10.8.1-src.zip/py4j/finalizer.py",
> line 43, in add_finalizer
> cls.finalizers[id] = weak_ref
> File "/usr/lib64/pypy-2.5.1/lib-python/2.7/threading.py", line 216, in
> __exit__
> self.release()
> File "/usr/lib64/pypy-2.5.1/lib-python/2.7/threading.py", line 208, in
> release
> self.__block.release()
> error: release unlocked lock
> {code}
> I assume it might not be directly related with the test itself but I noticed
> that it prev._is_barrier() attempts to access via Py4J.
> Accessing via Py4J is expensive and IMHO it makes it flaky.
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