Mark Payne created NIFI-2681:
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             Summary: Avoid caching Provenance Index Searchers
                 Key: NIFI-2681
                 URL: https://issues.apache.org/jira/browse/NIFI-2681
             Project: Apache NiFi
          Issue Type: Bug
          Components: Core Framework
            Reporter: Mark Payne
            Assignee: Mark Payne
            Priority: Critical
             Fix For: 1.1.0


In NIFI-2600 and NIFI-2452, we addressed two bugs where the Provenance 
Repository closes a cached IndexSearcher too soon. The IndexManager keeps the 
searchers cached in an effort to offer better performance when performing a 
Provenance Query. This was done because it was recommended in the Lucene 
documentation. However, we occasionally still see nodes crashing with segfaults 
due to the Lucene Searching. We should update the Persistent Provenance 
Repository to stop caching Index Searchers in order to trade a slight 
performance improvement for significantly better reliability.

Playing around with the idea in order to test it out shows very favorable 
results. On a system where I could cause a seg fault almost every time that I 
ran a large provenance query, I updated the code to no longer cache the readers 
and saw perfect stability with no noticeable performance degradation.

I will cleanup the code and submit a PR for these changes.



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