[jira] [Created] (IGNITE-26356) Clarify recommendations for -XX:MaxDirectMemorySize in docs

["Didar Shayarov (Jira)" <ji...@apache.org>]

Didar Shayarov created IGNITE-26356:
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             Summary: Clarify recommendations for -XX:MaxDirectMemorySize in docs
                 Key: IGNITE-26356
                 URL: https://issues.apache.org/jira/browse/IGNITE-26356
             Project: Ignite
          Issue Type: Improvement
          Components: documentation
    Affects Versions: 2.17
            Reporter: Didar Shayarov
            Assignee: Didar Shayarov
             Fix For: 2.18


Current documentation for memory tuning recommends setting -XX:MaxDirectMemorySize to walSegmentSize * 4 (if you use native persistance). 
This advice is misleading because the default limit for direct buffers is already equal to -Xmx. The formula may cause unnecessary OOME: Direct buffer memory errors and may mislead user to accidently decrease actual direct buffer size.
There is also legacy todo in code (since at least 2020) questioning this recommendations.
It is better to provide safer guidelines in docs.



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