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

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

michael goulish created DISPATCH-369:
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             Summary: 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


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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