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From Bill Havanki <bhava...@clouderagovt.com>
Subject Re: Supporting large values
Date Tue, 27 May 2014 20:55:18 GMT
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
>
>


-- 
// Bill Havanki
// Solutions Architect, Cloudera Govt Solutions
// 443.686.9283

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