[jira] [Created] (HBASE-18734) Possible memory leak when running mini cluster

["Samarth Jain (JIRA)" <ji...@apache.org>]

Samarth Jain created HBASE-18734:
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             Summary: Possible memory leak when running mini cluster
                 Key: HBASE-18734
                 URL: https://issues.apache.org/jira/browse/HBASE-18734
             Project: HBase
          Issue Type: Bug
            Reporter: Samarth Jain


As part of improving the stability of Phoenix tests, I recently did some analysis and found that when the mini cluster is not able to close all the regions properly, or if there is some other cruft left behind by a mini cluster after it has been shut down, it can result in a memory leak. The region server adds it's thread to the JVM shut down hook in HRegionServer.
{code}
ShutdownHook.install(conf, fs, this, Thread.currentThread());
{code}
So, even if the region server thread terminates when a mini cluster is shut down, the terminated thread's object stays around. If there is any remaining cruft (regions, configuration, etc) enclosed within a region server, GC isn't able to garbage them away since they are still referred to by this terminated thread object in the shutdown hook.

A possible/likely fix for this would be to call ShutdownHookManager.removeShutdownHook(regionServerThread) when the mini cluster is shut down.





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