Details
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Bug
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Status: Closed
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Major
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Resolution: Abandoned
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5.10.1, 5.11.0
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None
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None
Description
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.