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https://issues.apache.org/jira/browse/IGNITE-7820?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Maxim Muzafarov updated IGNITE-7820:
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Priority: Critical (was: Major)
> 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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