[jira] [Assigned] (LUCENE-7391) MemoryIndexReader.fields() performance regression

["David Smiley (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-7391?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

David Smiley reassigned LUCENE-7391:
------------------------------------

    Assignee: David Smiley

> MemoryIndexReader.fields() performance regression
> -------------------------------------------------
>
>                 Key: LUCENE-7391
>                 URL: https://issues.apache.org/jira/browse/LUCENE-7391
>             Project: Lucene - Core
>          Issue Type: Bug
>            Reporter: Steve Mason
>            Assignee: David Smiley
>         Attachments: LUCENE-7391-test.patch, LUCENE-7391.patch
>
>
> While upgrading our codebase from Lucene 4 to Lucene 6 we found a significant performance regression - a 5x slowdown
> On profiling the code, the method MemoryIndexReader.fields() shows up as one of the hottest methods
> Looking at the method, it just creates a copy of the inner {{fields}} Map before passing it to {{MemoryFields}}. It does this so that it can filter out fields with {{numTokens <= 0}}.
> The simplest "fix" would be to just remove the copying of the map completely, and pass {{fields}} directly to {{MemoryFields}}.  It's simple and removes any slowdown caused by this method.  It does potentially change behaviour though, but none of the unit tests seem to test that behaviour so I wonder whether it's necessary (I looked at the original ticket LUCENE-7091 that introduced this code, I can't find much in way of an explanation). I'm going to attach a patch to this effect anyway and we can take things from there



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@lucene.apache.org
For additional commands, e-mail: dev-help@lucene.apache.org