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Posted to dev@felix.apache.org by "Carsten Ziegeler (Jira)" <ji...@apache.org> on 2020/04/16 14:34:01 UTC
[jira] [Closed] (FELIX-6252) Deadlock in SCR ComponentRegistry
updateChangeCount
[ https://issues.apache.org/jira/browse/FELIX-6252?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Carsten Ziegeler closed FELIX-6252.
-----------------------------------
> Deadlock in SCR ComponentRegistry updateChangeCount
> ---------------------------------------------------
>
> Key: FELIX-6252
> URL: https://issues.apache.org/jira/browse/FELIX-6252
> Project: Felix
> Issue Type: Bug
> Components: Declarative Services (SCR)
> Affects Versions: scr-2.1.16
> Reporter: Karl Pauls
> Assignee: Carsten Ziegeler
> Priority: Major
> Fix For: scr-2.1.18
>
>
> There is a possible deadlock in the ComponentRegistry and it goes like this:
> The update of the change count is setting up a timer to execute a task while it is holding a lock. The task in turn, is grabbing that lock when activated and calls into the service registry while holding the lock.
> Now, when a service gets unregistered that is coming from a factory - the service registry will do an upcall that triggers scr to update the change count and hence, trying to grab the lock mentioned above.
> That can cause a case where the task has the lock and is waiting in the service registry which is waiting on scr, which is waiting for the lock.
> E.g.:
> For the tasks:
> {code:java}
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x00000007bc02ea40> (a java.util.concurrent.CountDownLatch$Sync)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
> at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
> at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:997)
> at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
> at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:231)
> at org.apache.felix.framework.ServiceRegistry.getService(ServiceRegistry.java:368)
> at org.apache.felix.framework.EventDispatcher.filterListenersUsingHooks(EventDispatcher.java:618)
> at org.apache.felix.framework.EventDispatcher.fireServiceEvent(EventDispatcher.java:542)
> at org.apache.felix.framework.Felix.fireServiceEvent(Felix.java:4833)
> at org.apache.felix.framework.Felix.access$000(Felix.java:112)
> at org.apache.felix.framework.Felix$1.serviceChanged(Felix.java:434)
> at org.apache.felix.framework.ServiceRegistry.servicePropertiesModified(ServiceRegistry.java:612)
> at org.apache.felix.framework.ServiceRegistrationImpl.setProperties(ServiceRegistrationImpl.java:132)
> at org.apache.felix.scr.impl.ComponentRegistry$4.run(ComponentRegistry.java:743)
> - locked <0x000000074376fb00> (a java.lang.Object)
> at java.util.TimerThread.mainLoop(Timer.java:555)
> at java.util.TimerThread.run(Timer.java:505)
> {code}
> and for the update:
> {code:java}
> java.lang.Thread.State: BLOCKED (on object monitor) at org.apache.felix.scr.impl.ComponentRegistry.updateChangeCount(ComponentRegistry.java:722) - waiting to lock <0x000000074376fb00> (a java.lang.Object) at org.apache.felix.scr.impl.BundleComponentActivator.updateChangeCount(BundleComponentActivator.java:778) at org.apache.felix.scr.impl.manager.AbstractComponentManager.setState(AbstractComponentManager.java:1420) at org.apache.felix.scr.impl.manager.SingleComponentManager.getServiceInternal(SingleComponentManager.java:962) at org.apache.felix.scr.impl.manager.SingleComponentManager.getService(SingleComponentManager.java:900) at org.apache.felix.framework.ServiceRegistrationImpl.getFactoryUnchecked(ServiceRegistrationImpl.java:348) at org.apache.felix.framework.ServiceRegistrationImpl.getService(ServiceRegistrationImpl.java:248) at org.apache.felix.framework.ServiceRegistry.getService(ServiceRegistry.java:350) at org.apache.felix.framework.EventDispatcher.filterListenersUsingHooks(EventDispatcher.java:618) at org.apache.felix.framework.EventDispatcher.fireServiceEvent(EventDispatcher.java:542) at org.apache.felix.framework.Felix.fireServiceEvent(Felix.java:4833) at org.apache.felix.framework.Felix.access$000(Felix.java:112) at org.apache.felix.framework.Felix$1.serviceChanged(Felix.java:434) at org.apache.felix.framework.ServiceRegistry.unregisterService(ServiceRegistry.java:170)
> {code}
> [~cziegeler], could you have a look and see if that is fixable by not holding the lock while calling into the serviceregistry?
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