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https://issues.apache.org/activemq/browse/AMQ-2103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=62505#action_62505
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Trevor Pounds commented on AMQ-2103:
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This fix looks like it will work but I do have some concerns implementing it as
a destination policy. Wouldn't it make more sense to implement this using
SoftReferences or a hook into the MarshallAware interface? In my opinion it
makes sense to clear memory at the discretion of the collector when the message
has been completely serialized to disk when there is not enough memory. The
actual problem I was trying to solve was to prevent "hidden" memory from
hanging around that was not tied to the ActiveMQ memory usage policies. I could
be missing something here but it seems there are disjoint philosophies for
memory management related to overall broker memory usage, fast dispatch cursors
and other unaccounted for "live" objects. I'm not sure what to do here but the
proposed fix (including my original submission) seems like a kludge at best.
Does anyone else have other opinions?
> Memory leak when marshaling ActiveMQTextMessage to persistent store
> -------------------------------------------------------------------
>
> Key: AMQ-2103
> URL: https://issues.apache.org/activemq/browse/AMQ-2103
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.0.0
> Environment: ActiveMQ 5.0.0.20-fuse
> Reporter: Trevor Pounds
> Assignee: Gary Tully
> Fix For: 5.5.0
>
> Attachments: AMQ-2103.diff, Duplicate Message Data (Internal
> Marshalling).png, heap_100_1MB_messages.png,
> jhat_ActiveMQTextMessage_0xe837a478.htm, jhat_ByteSequence_0xe837a5c0.htm,
> jhat_ByteSequence_data_0xe837adb0.htm
>
>
> When an org.apache.activemq.command.ActiveMQTextMessage is marshaled into the
> persistence store some portion of the messages are stored in memory (i.e.
> pending cursor/consumer dispatch queue). The messages stored in memory have
> the potential to cause the broker to run out of memory because
> org.apache.activemq.command.ActiveMQTextMessage objects can store the data
> twice, once in the 'text' field and once in the 'content' field. Normally
> this isn't a problem since the 'content' field is cleared when the message is
> being used in a client application (i.e. by calling getText() clears
> content). The problem occurs when a consumer is slow and a large number of
> messages are sitting around on the broker in pending/dispatch memory space.
> The message is marshaled for the store and then persisted to disk and copied
> to pending memory when space is available.
> This bug affects any ActiveMQ*Message object that does not clear its
> temporary data (i.e. 'text' field) once it has been marshaled. When a
> message is marshaled we should null the derived objects memory space once the
> data has been written to the parent object's 'content' field.
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