[jira] [Commented] (IGNITE-7820) Investigate and fix perfromance drop of WAL for FSYNC mode

["Maxim Muzafarov (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IGNITE-7820?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16943531#comment-16943531 ] 

Maxim Muzafarov commented on IGNITE-7820:
-----------------------------------------

[~agura]

Raised to `critical`. 
Is this issue still actual?

> Investigate and fix perfromance drop of WAL for FSYNC mode
> ----------------------------------------------------------
>
>                 Key: IGNITE-7820
>                 URL: https://issues.apache.org/jira/browse/IGNITE-7820
>             Project: Ignite
>          Issue Type: Bug
>    Affects Versions: 2.4
>            Reporter: Andrey N. Gura
>            Assignee: Andrey N. Gura
>            Priority: Critical
>             Fix For: 2.8
>
>
> WAL performance drop was introduced by https://issues.apache.org/jira/browse/IGNITE-6339 fix. In order to provide better performance for {{FSYNC}} WAL mode {{FsyncModeFileWriteAheadLogManager}} implementation was added as result of fix issue https://issues.apache.org/jira/browse/IGNITE-7594.
> *What we know about this performance drop:*
> * It affects {{IgnitePutAllBenchmark}} and {{IgnitePutAllTxBenchmark}} and measurements show 10-15% drop and ~50% drop accordingly.
> * It is reproducible not for all hardware configuration. That is for some configuration we see performance improvements instead of drop.
> * It is reproducible for [Many clients --> One server] topology.
> * If {{IGNITE_WAL_MMAP == false}} then we have better performance.
> * If {{fsyncDelay == 0}} then we have better performance.
> *What were tried during initial investigation:*
> * Replacing of {{LockSupport.park/unpark}} to spin leads to improvement about 2%.
> * Using {{FileWriteHandle.fsync(null)}} (unconditional flush) instead of {{FileWriteHandle.fsync(position)}} (conditional flush) doesn't affect benchmarks.
> *What should we do:*
> Investigate the problem and provide fix or recommendation for system tuning.



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