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From Josh Elser <josh.el...@gmail.com>
Subject Re: Supporting large values
Date Tue, 27 May 2014 21:04:39 GMT
Stack traces would definitely be helpful, IMO.

(or interesting if nothing else :D)

On 5/27/14, 4:55 PM, Bill Havanki wrote:
> No sir. I am seeing general out of heap space messages, nothing about
> direct buffers. One specific example would be while Thrift is writing to a
> ByteArrayOutputStream to send off scan results. (I can get an exact stack
> trace - easily :} - if it would be helpful.) It seems as if there just
> isn't enough heap left, after controlling for what I have so far.
>
> As a clarification of my original email: each row has 100 cells, and each
> cell has a 100 MB value. So, one row would occupy just over 10 GB.
>
>
> On Tue, May 27, 2014 at 4:49 PM, <dlmarion@comcast.net> wrote:
>
>> Are you seeing something similar to the error in
>> https://issues.apache.org/jira/browse/ACCUMULO-2495?
>>
>> ----- Original Message -----
>>
>> From: "Bill Havanki" <bhavanki@clouderagovt.com>
>> To: "Accumulo Dev List" <dev@accumulo.apache.org>
>> Sent: Tuesday, May 27, 2014 4:30:59 PM
>> Subject: Supporting large values
>>
>> I'm trying to run a stress test where each row in a table has 100 cells,
>> each with a value of 100 MB of random data. (This is using Bill Slacum's
>> memory stress test tool). Despite fiddling with the cluster configuration,
>> I always run out of tablet server heap space before too long.
>>
>> Here are the configurations I've tried so far, with valuable guidance from
>> Busbey and madrob:
>>
>> - native maps are enabled, tserver.memory.maps.max = 8G
>> - table.compaction.minor.logs.threshold = 8
>> - tserver.walog.max.size = 1G
>> - Tablet server has 4G heap (-Xmx4g)
>> - table is pre-split into 8 tablets (split points 0x20, 0x40, 0x60, ...), 5
>> tablet servers are available
>> - tserver.cache.data.size = 256M
>> - tserver.cache.index.size = 40M (keys are small - 4 bytes - in this test)
>> - table.scan.max.memory = 256M
>> - tserver.readahead.concurrent.max = 4 (default is 16)
>>
>> It's often hard to tell where the OOM error comes from, but I have seen it
>> frequently coming from Thrift as it is writing out scan results.
>>
>> Does anyone have any good conventions for supporting large values?
>> (Warning: I'll want to work on large keys (and tiny values) next! :) )
>>
>> Thanks very much
>> Bill
>>
>> --
>> // Bill Havanki
>> // Solutions Architect, Cloudera Govt Solutions
>> // 443.686.9283
>>
>>
>
>

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