[jira] [Created] (IGNITE-15460) Incorrect "Set max direct memory size" suggestion

["Alexey Kukushkin (Jira)" <ji...@apache.org>]

Alexey Kukushkin created IGNITE-15460:
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             Summary: Incorrect "Set max direct memory size" suggestion
                 Key: IGNITE-15460
                 URL: https://issues.apache.org/jira/browse/IGNITE-15460
             Project: Ignite
          Issue Type: Improvement
    Affects Versions: 2.10
            Reporter: Alexey Kukushkin


Ignite always outputs this performance suggestion on startup:

{{Set max direct memory size if getting 'OOME: Direct buffer memory' (add '-XX:MaxDirectMemorySize=<size>[g|G|m|M|k|K]' to JVM options)}}

 

That is incorrect since:
 * The Ignite [Memory and JVM Tuning|https://ignite.apache.org/docs/latest/perf-and-troubleshooting/memory-tuning#memory-and-jvm-tuning] page suggests NOT to explicitly set the {{MaxDirectMemorySize}} (unless native persistence is used but in this case set it to {{walSegmentSize * 4}}). Not setting {{MaxDirectMemorySize}} seems the right default option since in this case JVM would choose the most appropriate default size.
 * Increasing direct memory size when getting OOME for direct memory seems too obvious to always print this information.



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