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From Keith Turner <ke...@deenlo.com>
Subject Re: [jira] [Commented] (ACCUMULO-624) iterators may open lots of compressors
Date Thu, 21 Jun 2012 19:15:58 GMT
I added a comment on the ticket

On Thu, Jun 21, 2012 at 1:38 PM, David Medinets
<david.medinets@gmail.com> wrote:
> Is the testing code simple enough to attach to this ticket? I ask
> because others might want to replicate your results.
>
> On Thu, Jun 21, 2012 at 12:27 PM, Keith Turner (JIRA) <jira@apache.org> wrote:
>>
>>    [ https://issues.apache.org/jira/browse/ACCUMULO-624?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13398538#comment-13398538
]
>>
>> Keith Turner commented on ACCUMULO-624:
>> ---------------------------------------
>>
>> A work around for this issue is to enable the block cache for the table.  This will
cause rfile blocks to be read into memory and closed immediately, releasing the decompressor.
 A decompressor will not be kept for each deep copy in this case.
>>
>> I did some test with the intersecting iterator to verify this.  W/o cache querying
5 terms would allocate 5 decompressors.  W/ cache only one decompressor was allocated.
>>
>>> 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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>>
>>

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