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From "Kevin Burton (JIRA)" <j...@apache.org>
Subject [jira] [Created] (AMQ-5609) ActiveMQ locks out new consumers/producers during queue GC
Date Mon, 23 Feb 2015 18:44:11 GMT
Kevin Burton created AMQ-5609:
---------------------------------

             Summary: ActiveMQ locks out new consumers/producers during queue GC
                 Key: AMQ-5609
                 URL: https://issues.apache.org/jira/browse/AMQ-5609
             Project: ActiveMQ
          Issue Type: Bug
          Components: Broker
    Affects Versions: 5.11.0, 5.10.1
            Reporter: Kevin Burton


ActiveMQ supports a feature where it can GC a queue that is inactive. IE now messages and
no consumers.

However, there’s a bug where 

purgeInactiveDestinations 

in 

org.apache.activemq.broker.region.RegionBroker

creates a read/write lock (inactiveDestinationsPurgeLock) which is held during the entire
queue GC.

each individual queue GC takes about 100ms with a disk backed queue and 10ms with a memory
backed (non-persistent) queue. If you have thousands of them to GC at once the inactiveDestinationsPurgeLock
lock is held the entire time which can last from 60 seconds to 5 minutes (and essentially
unbounded).

A read lock is also held for this in addConsumer addProducer so that when a new consumer or
produce tries to connect, they’re blocked until queue GC completes.

Existing producers/consumers work JUST fine.  

The lock MUST be held on each queue because if it isn’t there’s a race where a queue is
flagged to be GCd , then a producer comes in and writes a new message, then the background
thread deletes the queue which it marked as GCable but it had the newly produced message.
 This would result in data loss.



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