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From "Kelly Campbell (JIRA)" <j...@apache.org>
Subject [jira] Commented: (AMQ-932) Quickly broken client connections lead to memory leaks
Date Sat, 23 Sep 2006 17:52:23 GMT
    [ https://issues.apache.org/activemq/browse/AMQ-932?page=comments#action_36997 ] 
            
Kelly Campbell commented on AMQ-932:
------------------------------------

I ran into a similar issue but I don't think it was due to broken connections. I've got a
heap dump from the broker (jdk1.6), and it looks like the OpenWireFormat marshalCache is the
root cause of the one I'm working on. Each DataStructure[] marshalCache is roughly 64K because
of the MARSHAL_CACHE_SIZE. There's 738 DataStructure[] arrays in my heap, taking up 48 Mbytes.
Most of these only have one element used. 

I think issues 914 and 937 might be related or the same. 

> Quickly broken client connections lead to memory leaks
> ------------------------------------------------------
>
>                 Key: AMQ-932
>                 URL: https://issues.apache.org/activemq/browse/AMQ-932
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 4.0.2
>            Reporter: John Heitmann
>         Attachments: 73.diff
>
>
> Connections to the openwire port that are pathologically broken (for example any http
request) or that die in some other way extremely quickly will lead to memory losses of aout
64Kb each time. This happens because many services are stop()ed directly in the middle of
start(), and then never stopped for real, or stopped again but on an object tree with an inconsistent
state. This is usually also accompanied by the JMX message:
> WARN  ManagedTransportConnection     - Failed to unregister mbean: org.apache.activemq:BrokerName=localhost,Type=Connection,ConnectorName=default,Connection=25
> But that is a cosmetic symptom and not critical (and this has otherwise nothing to do
with JMX).
> My patch is a band-aid that is functional but I'm not very happy with it. The patch changes
some service logic so that if stop is called in the middle of start, the stop is instead queued
and called at the end of start. There will still be multiple stops, and you'll still see the
cosmetic JMX error from the second ineffectual stop, but the first stop cleans up correctly
so there are no leaks.
> I think there's probably a better solution, but it was tough to see what. I'd appreciate
better ideas. Possibly something involving moving the dangerous operations (wire format negotiation
etc) out of start?
> I am working on a unit test, but I can't promise I will have something to submit. I'm
having to play JVM games to detect the problem in a unit test and that might not fly for general
purpose use.

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