[jira] [Created] (SOLR-13393) ZkClientClusterStateProvider can leak ZkStateReader (and associated watcher threads) if background threads attempt to use it after close() .

["Hoss Man (JIRA)" <ji...@apache.org>]

Hoss Man created SOLR-13393:
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             Summary: ZkClientClusterStateProvider can leak ZkStateReader (and associated watcher threads) if background threads attempt to use it after close() .
                 Key: SOLR-13393
                 URL: https://issues.apache.org/jira/browse/SOLR-13393
             Project: Solr
          Issue Type: Bug
      Security Level: Public (Default Security Level. Issues are Public)
            Reporter: Hoss Man
            Assignee: Hoss Man


while digging into some test failures related to leaked ZkStateReader objects, i noticed a pattern which i beleive can be explained by the fact that ZkClientClusterStateProvider does not complain/fail if some caller tries to connect()/use it after it's already been closed – in this situation it will just re-create a new ZkStateReader (which is later leaked)

So in in situations where background/timer threads use a SolrClientCloudManager/ZkClientClusterStateProvider, we might see...
{noformat}
T1 : start shutdown...
T1 :  ...SolrClientCloudManager.close()...
T1 :   ...ZkClientClusterStateProvider.close()...
T1 :    ...ZkStateReader.close()
T1 :    ...zkStateReader = null;
T 2: run background thread/task/trigger...
T 2:  ...get ZkClientClusterStateProvider
T 2:  ...call ZkClientClusterStateProvider.connect()
T 2:   ...zkStateReader = new ZkStateReader()                 /* LEAKED */
T 2:  ... do something with ZkClientClusterStateProvider
T 2:  ...finish background thread/task/trigger
T1 :  ...finish shutdown of ZkClientClusterStateProvider / SolrClientCloudManager
{noformat}



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