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Posted to issues@lucene.apache.org by "Kevin Risden (Jira)" <ji...@apache.org> on 2022/05/16 17:46:00 UTC

[jira] [Updated] (LUCENE-10576) ConcurrentMergeScheduler maxThreadCount calculation is artificially low

     [ https://issues.apache.org/jira/browse/LUCENE-10576?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kevin Risden updated LUCENE-10576:
----------------------------------
    Description: 
https://github.com/apache/lucene/blob/main/lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java#L177

{code:java}
maxThreadCount = Math.max(1, Math.min(4, coreCount / 2));
{code}

This has a practical limit of max of 4 threads due to the Math.min. This doesn't take into account higher coreCount.

I can't seem to tell if this is by design or this is just a mix up of logic during the calculation.

If I understand it looks like 1 and 4 are mixed up and should instead be:

{code:java}
maxThreadCount = Math.max(4, Math.min(1, coreCount / 2));
{code}

which then simplifies to

{code:java}
maxThreadCount = Math.max(4, coreCount / 2);
{code}

So that you have a minimum of 4 maxThreadCount and max of coreCount/2.

  was:
https://github.com/apache/lucene/blob/main/lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java#L177

{code:java}
maxThreadCount = Math.max(1, Math.min(4, coreCount / 2));
{code}

This has a practical limit of max of 4 threads due to the Math.min. This doesn't take into account higher coreCount.

I can't seem to tell if this is by design or this is just a mix up of logic during the calculation.




> ConcurrentMergeScheduler maxThreadCount calculation is artificially low
> -----------------------------------------------------------------------
>
>                 Key: LUCENE-10576
>                 URL: https://issues.apache.org/jira/browse/LUCENE-10576
>             Project: Lucene - Core
>          Issue Type: Bug
>            Reporter: Kevin Risden
>            Priority: Major
>
> https://github.com/apache/lucene/blob/main/lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java#L177
> {code:java}
> maxThreadCount = Math.max(1, Math.min(4, coreCount / 2));
> {code}
> This has a practical limit of max of 4 threads due to the Math.min. This doesn't take into account higher coreCount.
> I can't seem to tell if this is by design or this is just a mix up of logic during the calculation.
> If I understand it looks like 1 and 4 are mixed up and should instead be:
> {code:java}
> maxThreadCount = Math.max(4, Math.min(1, coreCount / 2));
> {code}
> which then simplifies to
> {code:java}
> maxThreadCount = Math.max(4, coreCount / 2);
> {code}
> So that you have a minimum of 4 maxThreadCount and max of coreCount/2.



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