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Posted to oak-issues@jackrabbit.apache.org by "Alex Parvulescu (JIRA)" <ji...@apache.org> on 2016/11/10 08:09:59 UTC

[jira] [Assigned] (OAK-4987) Segment objects under-report their size for the cache

     [ https://issues.apache.org/jira/browse/OAK-4987?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alex Parvulescu reassigned OAK-4987:
------------------------------------

    Assignee: Alex Parvulescu

> Segment objects under-report their size for the cache
> -----------------------------------------------------
>
>                 Key: OAK-4987
>                 URL: https://issues.apache.org/jira/browse/OAK-4987
>             Project: Jackrabbit Oak
>          Issue Type: Bug
>          Components: segment-tar
>            Reporter: Alex Parvulescu
>            Assignee: Alex Parvulescu
>             Fix For: 1.5.14
>
>
> The {{SegmentCache}} expects each {{Segment}} object to report its own size, which will then be used to properly keep the cache within the configured bounds [0]. If a {{Segment}} object is unable to accurately account for its own size the global cache will have a size that is a lot bigger than the expected value:
> {noformat}
> Class Name                                                                   | Shallow Heap | Retained Heap | Percentage
> -------------------------------------------------------------------------------------------------------------------------
> org.apache.jackrabbit.oak.segment.Segment @ 0x6cd906df0                      |           48 |     1 439 728 |      0,09%
> |- org.apache.jackrabbit.oak.segment.ImmutableRecordNumbers @ 0x6cd906e50    |           16 |     1 177 432 |      0,07%
> |- java.nio.HeapByteBuffer @ 0x6cd906e20                                     |           48 |       262 208 |      0,02%
> |- org.apache.jackrabbit.oak.segment.ImmutableSegmentReferences @ 0x6ce0a0880|           16 |            40 |      0,00%
> -------------------------------------------------------------------------------------------------------------------------
> {noformat}
> This is pre OAK-4872, so the objects won't match anymore, but the core issue is still there (segment size needs to account for {{segmentReferences}} and {{recordNumbers}}).
> [0] https://github.com/apache/jackrabbit-oak/blob/trunk/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/SegmentCache.java#L53



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