Details
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Bug
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Status: Resolved
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Major
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Resolution: Fixed
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2.18.0, 2.19.0, 2.20.0, 2.21.0, 2.22.0, 2.23.0
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None
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Java 10
Karaf 4.2.1
Camel 2.22.0
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Patch Available
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Unknown
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Patch
Description
The OsgiServiceRegistry has a slow memory leak in the serviceReferenceQueue. Currently every time a service is looked up by any method an item is added to the serviceReferenceQueue. This is required because of OSGi ServiceReference counting. However left unchecked the system just continues to add ConcurrentLinkedQueue$Node objects until memory is exhausted.
.
There is also a second problem with how the registry is being managed within the OsgiDefaultCamelContext. OsgiServiceRegistry is currently extends LifecycleStrategySupport which is suppose to unload the serviceReferenceQueue onContextStop. However the registry is never getting added to the CamelContext to manage the Lifecycle because the overridden createRegistry method in OsgiDefaultCamelContext is not being called. This is because the registry is being set in the constructor of OsgiDefaultCamelContext with
super(registry);
this calls the DefaultCamelContext implementation of createRegistry which does not add the registry to lifecyclemanagement since
OsgiCamelContextHelper.wrapRegistry(this, registry, bundleContext);
is never called.
See serviceReferenceQueue pre context stop
See serviceReferenceQueue post context stop (still contain objects)
Both issues would have existed for some time but may have gone unnoticed because the leak was so slow (ConcurrentLinkedQueue$Node takes up very little memory). It appears the removal of the cache in https://issues.apache.org/jira/browse/CAMEL-9631 makes the leak occur more quickly.
I have a patch that involves reintroducing the cache but with an invalidation strategy using the OSGi ServiceListener that leverages a single clean up thread to remain non-blocking. I'm working on an upstream adaptation and will post a PR for community review.
