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https://issues.apache.org/jira/browse/QPID-942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12763466#action_12763466
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Martin Ritchie commented on QPID-942:
-------------------------------------
Hi Rob, would be cleaner for the test to reuse the QpidTestCase
setSystemProperty option, or setTestClientSystemProperty if the property has an
undesired impact on the broker. This will ensure that the value get correctly
reset at the end of the test. Currently a failure of your tests will leave the
test value set.
> Introduce client flow control and broker overflow protection
> ------------------------------------------------------------
>
> Key: QPID-942
> URL: https://issues.apache.org/jira/browse/QPID-942
> Project: Qpid
> Issue Type: New Feature
> Components: Java Broker, Java Client
> Reporter: Marnie McCormack
> Assignee: Rob Godfrey
> Fix For: 0.6
>
>
> Certainly the Java, and probably the other clients do not obey flow-control
> commands from the broker. The Java broker never sends them to clients either.
> This is in the 0-8 spec. so not fully AMQP compliant without it.
> Client Work
> -------------------
> Flow control to be implemented in clients. The clients must also have buffer
> limiting in place prior to this, or flow-controlling a client will only shift
> OOMEs from the broker to the clients. Bounded buffers plus back-pressure from
> the broker will should ultimately lead to the 'send' method blocking once the
> system as a whole is completely saturated. This may mean that the broker gets
> a needed opportunity to chew its way through the back-log, resulting in
> healthy throughputs under saturation.
> Broker Work
> ------------------
> A strategy for deciding when to flow control clients from the broker needs to
> be decided upon. Flow-control has per-connection granularity, which makes
> deciding when to do it on a per route basis awkward. Flow-control may be
> triggered by:
> 1. The broker being low on memory globally across the message store and all
> queues.
> 2. A client attempting to publish to a queue that is beyond its max-depth.
> 3. Based on history of destinations a client usually publishes to (or has
> published to), flow-control client if one of them is beyond max-depth.
> A well-conditioned application will not experience 'send' blocking, except
> under exceptional loads, whereupon it will act as a safety valve to prevent
> either clients or broker from throwing OOME. The other scenario that may
> cause back-logs, is slow consumers without TTL.
> No time estimate for this yet, as its a fairly large piece of work, and not
> yet decided exactly how its to be done. Need a design proposal before
> starting work, to be reviewed by the qpid-dev group.
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