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From "Josh Elser (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-1770) out of memory error on very long running tablet server
Date Fri, 11 Oct 2013 15:52:42 GMT


Josh Elser commented on ACCUMULO-1770:

bq. The one fact that bothers me is the use of swap without a negative impact on performance

Hypothetically, I could see that. For example, what if you have a bunch of jars in lib or
lib/ext that you use very infrequently. These could be swapped to disk and you likely wouldn't
pay any penalty because you aren't using them. Of course, that's just a guess and isn't founded
at all (which goes back to your 'lack of tools to help' comment).

> out of memory error on very long running tablet server
> ------------------------------------------------------
>                 Key: ACCUMULO-1770
>                 URL:
>             Project: Accumulo
>          Issue Type: Bug
>          Components: tserver
>            Reporter: Eric Newton
>            Assignee: Eric Newton
>         Attachments:, memory-usage.png
> On a large cluster it was noticed that a few of the tablet servers had been pushed into
swap.  This didn't effect the performance of the server until it ran out of memory, and the
process was killed.  The gc reports in the debug log showed the system had plenty of heap
space for the JVM.  The number of threads in the server were not excessive (dozens).  This
cluster ingests some large values (megabytes).  The tablet server had been up for a month
prior to running out of memory.  MALLOC_ARENA_MAX had already been set to 1.
> * Investigate the effect of fragmentation on memory usage for large value inserts.

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