[jira] [Commented] (LUCENE-8635) Lazy loading Lucene FST offheap using mmap

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[jira] [Commented] (LUCENE-8635) Lazy loading Lucene FST offheap using mmap

JIRA jira@apache.org

    [ https://issues.apache.org/jira/browse/LUCENE-8635?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16740764#comment-16740764 ]

Michael McCandless commented on LUCENE-8635:
--------------------------------------------

Also, have you confirmed that all tests pass when you switch to off heap FST storage always?

> Lazy loading Lucene FST offheap using mmap
> ------------------------------------------
>
>                 Key: LUCENE-8635
>                 URL: https://issues.apache.org/jira/browse/LUCENE-8635
>             Project: Lucene - Core
>          Issue Type: New Feature
>          Components: core/FSTs
>         Environment: I used below setup for es_rally tests:
> single node i3.xlarge running ES 6.5
> es_rally was running on another i3.xlarge instance
>            Reporter: Ankit Jain
>            Priority: Major
>         Attachments: offheap.patch, rally_benchmark.xlsx
>
>
> Currently, FST loads all the terms into heap memory during index open. This causes frequent JVM OOM issues if the term size gets big. A better way of doing this will be to lazily load FST using mmap. That ensures only the required terms get loaded into memory.
>  
> Lucene can expose API for providing list of fields to load terms offheap. I'm planning to take following approach for this:
>  # Add a boolean property fstOffHeap in FieldInfo
>  # Pass list of offheap fields to lucene during index open (ALL can be special keyword for loading ALL fields offheap)
>  # Initialize the fstOffHeap property during lucene index open
>  # FieldReader invokes default FST constructor or OffHeap constructor based on fstOffHeap field
>  
> I created a patch (that loads all fields offheap), did some benchmarks using es_rally and results look good.



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