[low-priority] Close bridged instruments when GC'd#16219
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laurit merged 9 commits intoopen-telemetry:mainfrom Mar 30, 2026
Merged
[low-priority] Close bridged instruments when GC'd#16219laurit merged 9 commits intoopen-telemetry:mainfrom
laurit merged 9 commits intoopen-telemetry:mainfrom
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| Consumer<application.io.opentelemetry.api.metrics.ObservableDoubleMeasurement> | ||
| applicationCallback) { | ||
| return new ApplicationObservableDoubleCounter( | ||
| agentBuilder.buildWithCallback( |
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should we also handle calling close on the returned ObservableDoubleCounter and remove the callback from the list so it could be collected immediately?
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| // Anchors callbacks to this class's lifecycle. Since this class is injected as a helper into each | ||
| // application class loader, callbacks are naturally tied to their class loader's lifecycle. | ||
| private static final Set<Object> callbacks = ConcurrentHashMap.newKeySet(); |
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Ideally I think this should be an identity set to guard agains callbacks with weird equals/hashCode. To handle using the same callback for multiple instruments where one of the instruments gets closed it would need to use ref counting. I think we can ignore these for now.
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Currently, when the agent bridges an async instrument callback (e.g.
buildWithCallback), the SDKends up holding a strong reference chain back to the app classloader:
This pins the app classloader forever, leaking memory on tomcat webapp redeploys.
This PR breaks the chain with a
WeakReference, then anchors the bridging lambda to the app classloader's own lifecycle so it stays alive exactly as long as the classloader does:(all good ideas here are credit to @laurit, all bad implementation details are credit to me)