[jira] [Created] (HIVE-16949) Leak of threads from Get-Input-Paths thread pool when more than 1 used in query

["Birger Brunswiek (JIRA)" <ji...@apache.org>]

Birger Brunswiek created HIVE-16949:
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             Summary: Leak of threads from Get-Input-Paths thread pool when more than 1 used in query
                 Key: HIVE-16949
                 URL: https://issues.apache.org/jira/browse/HIVE-16949
             Project: Hive
          Issue Type: Bug
          Components: HiveServer2
            Reporter: Birger Brunswiek


The commit 7f1c29ebe which was part of HIVE-15881 introduced a thread pool for which is not shutdown upon completion of its threads. This leads to a leak of threads. They are not removed by the GC. When queries spanning multiple partitions are made the number of threads increases and is never reduced. On my machine hiveserver2 starts to get slower and slower once 10k threads are reached.

Thread pools should be should be [shutdown automatically|https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ThreadPoolExecutor.html]. I am not sure why this is not the case. I would add a _pool.shutdown()_ just [after the pool has completed its work|https://github.com/apache/hive/blob/824b9c80b443dc4e2b9ad35214a23ac756e75234/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#L3137] to make sure the threads are really shutdown.

My current workaround is to set {{hive.exec.input.listing.max.threads = 1}}. This prevents the the thread pool from being spawned [\[1\]|https://github.com/apache/hive/blob/824b9c80b443dc4e2b9ad35214a23ac756e75234/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#L2118] [\[2\]|https://github.com/apache/hive/blob/824b9c80b443dc4e2b9ad35214a23ac756e75234/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#L3107].





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