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From "ASF GitHub Bot (JIRA)" <>
Subject [jira] [Commented] (NIFI-2681) Avoid caching Provenance Index Searchers
Date Tue, 06 Sep 2016 15:11:20 GMT


ASF GitHub Bot commented on NIFI-2681:

Github user bbende commented on the issue:

> Avoid caching Provenance Index Searchers
> ----------------------------------------
>                 Key: NIFI-2681
>                 URL:
>             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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