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https://issues.apache.org/jira/browse/AMQ-4977?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Timothy Bish resolved AMQ-4977.
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Resolution: Fixed
Fix Version/s: 5.10.0
Assignee: Timothy Bish
I've committed a small test and fix for the cache size value growing when
nothing is actually added into the map. Since there was no test provided to
confirm this fixes the underlying issue you'll need to test and report back at
some point if there is still more going on.
> Memory leak in ConnectionStateTracker when browsing non-empty queues
> --------------------------------------------------------------------
>
> Key: AMQ-4977
> URL: https://issues.apache.org/jira/browse/AMQ-4977
> Project: ActiveMQ
> Issue Type: Bug
> Affects Versions: 5.6.0, 5.7.0, 5.8.0, 5.9.0
> Reporter: Georgi Danov
> Assignee: Timothy Bish
> Fix For: 5.10.0
>
>
> I think I found case that is not handled by the fix AMQ-3316. We see memory
> leaks connected to this bug and after good amount of headbanging I think the
> problem is in how two methods work together - processMessagePull and
> trackBack. The first one has this piece of code:
> {code}
> // leave a single instance in the cache
> final String id = pull.getDestination() + "::" +
> pull.getConsumerId();
> messageCache.put(id.intern(), pull);
> {code}
> while the second one unconditionally increases the currentCacheSize -
> regardless if the previous method added or replaced entry in the cache.
> The situation where entries will be replaced (and not added) and the
> currentCacheSize will grow very fast until it wraps around and becomes
> negative is the following:
> * have some logic that frequently creates queue browser and iterates through
> all the entries
> * have the queue most of the time with at least one message. The more
> messages in the queue the faster currentCacheSize grows.
> The reason is that processMessagePull reuses the consumer and destination ID
> for each browsed message in the queue when
> org.apache.activemq.ActiveMQQueueBrowser#hasMoreElements is invoked.
> trackBack is ignorant of this and keeps adding to the size regardless that
> the cache size stays the same.
> Here is log from reproducing the issue as a proof:
> {code}
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 10000, 5 elements, pending scans:10, memory: 8951KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 20000, 10 elements, pending scans:10, memory: 10845KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 30000, 15 elements, pending scans:10, memory: 12645KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 40000, 20 elements, pending scans:10, memory: 10363KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 50000, 25 elements, pending scans:10, memory: 12169KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 60000, 30 elements, pending scans:10, memory: 9852KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 70000, 35 elements, pending scans:10, memory: 11657KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 80000, 40 elements, pending scans:10, memory: 9401KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 90000, 45 elements, pending scans:10, memory: 11222KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 100000, 50 elements, pending scans:10, memory: 13047KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 110000, 55 elements, pending scans:10, memory: 10767KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 120000, 60 elements, pending scans:10, memory: 12567KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 130000, 65 elements, pending scans:10, memory: 10256KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 138800, 67 elements, pending scans:10, memory: 12085KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 146800, 67 elements, pending scans:10, memory: 9745KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 154800, 67 elements, pending scans:10, memory: 11566KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 162800, 67 elements, pending scans:10, memory: 9225KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 170800, 67 elements, pending scans:10, memory: 11013KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 178800, 67 elements, pending scans:10, memory: 12812KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 186800, 67 elements, pending scans:10, memory: 10522KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 194800, 67 elements, pending scans:10, memory: 12328KB
> 2014-01-16 23:05:14 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 202800, 67 elements, pending scans:10, memory: 9999KB
> 2014-01-16 23:05:15 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 210800, 67 elements, pending scans:10, memory: 11805KB
> 2014-01-16 23:05:15 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 218800, 67 elements, pending scans:10, memory: 9496KB
> 2014-01-16 23:05:15 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 226800, 67 elements, pending scans:10, memory: 11316KB
> 2014-01-16 23:05:15 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 234800, 67 elements, pending scans:10, memory: 13100KB
> 2014-01-16 23:05:15 WARN ActiveMqMemoryLeakTest - MaxCacheSize: 131072,
> currentCacheSize: 242800, 67 elements, pending scans:10, memory: 10754KB
> {code}
> One can see that the garbage collection works well (cache does not grow) but
> the currentCacheSize keeps increasing
> Unfortunately I cannot easily extract the original code and provide it. Hope
> the explanation is clear enough.
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