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https://issues.apache.org/jira/browse/ACCUMULO-624?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13398761#comment-13398761
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Keith Turner commented on ACCUMULO-624:
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The experiment I did was the following :
* Edit conf/generic_logger.xml and set
org.apache.accumulo.core.file.rfile.bcfile to DEBUG
* Start tservers
* Look at shard example and run the query command (after indexing)
* Look at tserver logs, should see messages about allocating and deallocting
multiple decompressors
* Enable block cache on shard table
* Major compact table or wait a few minutes for file to close, file open by
previous query does not have cache set
* run shard example query again
* look at tservers logs, should only see one decompressor used
* subsequent queries may not show any decompressor use because data is cached
> iterators may open lots of compressors
> --------------------------------------
>
> Key: ACCUMULO-624
> URL: https://issues.apache.org/jira/browse/ACCUMULO-624
> Project: Accumulo
> Issue Type: Bug
> Components: tserver
> Reporter: Eric Newton
> Assignee: Keith Turner
>
> A large iterator tree may create many instances of Compressors. These
> instances are pulled from a pool that never decreases in size. So, if 50
> simultaneous queries are run over dozens of files, each with a complex
> iterator stack, there will be thousands of compressors created. Each of
> these holds a large buffer. This can cause the server to run out of memory.
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