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https://issues.apache.org/jira/browse/TEZ-3732?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16013558#comment-16013558
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Gopal V commented on TEZ-3732:
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[~jeagles]: can you post a "jol internals" dump from the before/after?
> Reduce Object size of InputAttemptIdentifier and MapOutput for large jobs
> -------------------------------------------------------------------------
>
> Key: TEZ-3732
> URL: https://issues.apache.org/jira/browse/TEZ-3732
> Project: Apache Tez
> Issue Type: Bug
> Reporter: Jonathan Eagles
> Assignee: Jonathan Eagles
>
> Objects in 64bit java are 12bytes + member size aligned to 8 bytes
> InputAttemptIdentifier -> 33Bytes gets aligned up to 40 bytes
> This class is just one byte over the 32 byte alignment. Reducing object size
> by one byte can save 8 bytes per object.
> This is ~8MB savings for 1,000,000 inputs and ~80 MB savings for tasks with
> 10,000,000 inputs to fetch (Yes this is a real job)
> MapOutput -> 45 bytes gets aligned to 48 bytes
> This class can be sub-classed to avoid all sub-classes paying the object size
> cost for the other sub-classes
> Wait InMemory and DiskDirect -> 32 bytes
> Disk -> 40 bytes
> Total savings is harder to account for but more than the above case.
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