[jira] [Commented] (DISPATCH-369) investigate excursions in memory usage

["michael goulish (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DISPATCH-369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15321448#comment-15321448 ] 

michael goulish commented on DISPATCH-369:
------------------------------------------

I rebuilt dispatch without the memory pooling feature, expecting that this would make the memory blow-ups go away.  It did not!  On the 7th run of my test, I saw memory go from 60 MB  (Resident Set Size) to 480 MB between one printout of 'top' and the next.  (3 seconds)  -- same behavior I was seeing with memory pooling enabled.

> investigate excursions in memory usage
> --------------------------------------
>
>                 Key: DISPATCH-369
>                 URL: https://issues.apache.org/jira/browse/DISPATCH-369
>             Project: Qpid Dispatch
>          Issue Type: Bug
>          Components: Router Node
>    Affects Versions: 0.6.0
>            Reporter: michael goulish
>            Assignee: michael goulish
>         Attachments: n_senders_vs_MEM_three_trials.jpg
>
>
> I don't know if this is a bug or not.  I'm Jirifying it as a way of remembering an interesting behavior that my testing has shown, so that I can continue developing the testing and  come back to this later.
> ...
> While measuring router memory usage under varying message rate and number of senders -- when I run the same test multiple times, I am occasionally (about 1 in 4 times or so) seeing a test in which memory usage is much higher than the others.
> For example:
>   In this test:
>   {
>     straight-through topology ( 1 sender --> 1 address --> 1 receiver )
>     200 senders
>     200 messages per second
>     100 bytes per message
>   }
> I record router memory usage at the point when all receivers are just hitting 10,000 messages.   (This is because it grows -- see previous JIRA.)
> In three iterations I get the following memory usage:
>    66 MB
>    63 MB
>   181 MB
> Something similar, but less drastic, happened occasionally at lower levels in the test.  
> In this case, this is a tripling of memory usage for the same scenario.  I doubt that this is the result of slightly  different timing in a block allocation of data structures.  What just happened?
> Start by investigating with "qdstat -m"  and see if that shows some or all of the difference.



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