[FELIX-3687] Deadlock potential from ServiceRegistry.unregisterService

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: framework-4.0.3
• Component/s: Framework
• Assignee: Unassigned
• Reporter: David Jencks
• Created: 27/Sep/12 21:32
• Updated: 13/Mar/14 08:25
• Resolved: 13/Mar/14 08:25

Description

At the end of unregisterService there's this block:

        // Now forcibly unget the service object for all stubborn clients.
        synchronized (this)
        {
            Bundle[] clients = getUsingBundles(reg.getReference());
            for (int i = 0; (clients != null) && (i < clients.length); i++)
            {
                while (ungetService(clients[i], reg.getReference()))
                    ; // Keep removing until it is no longer possible
            }
            ((ServiceRegistrationImpl) reg).invalidate();
        }

Note the call to ungetService from within a synchronized block. ungetService itself is very careful to release the lock before calling out to the service factory, however this call from unregisterService negates this care.

This causes problems with DS with thread dumps like:

ThreadId: 16 : name: SCR Component Actor State: RUNNABLE
  LockInfo: null LockOwnerId: -1 LockOwnerName: null
  sun.management.ThreadImpl.dumpThreads0(Native Method)
  sun.management.ThreadImpl.dumpAllThreads(ThreadImpl.java:433)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.dumpThreads(AbstractComponentManager.java:294)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.logLockingInfo(AbstractComponentManager.java:240)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.releaseReadLock(AbstractComponentManager.java:222)
  org.apache.felix.scr.impl.manager.ImmediateComponentManager.ungetService(ImmediateComponentManager.java:710)
  org.apache.felix.framework.ServiceRegistrationImpl.ungetFactoryUnchecked(ServiceRegistrationImpl.java:349)
  org.apache.felix.framework.ServiceRegistrationImpl.ungetService(ServiceRegistrationImpl.java:258)
  org.apache.felix.framework.ServiceRegistry.ungetService(ServiceRegistry.java:389)
  org.apache.felix.framework.Felix.ungetService(Felix.java:3432)
  org.apache.felix.framework.BundleContextImpl.ungetService(BundleContextImpl.java:486)
  org.apache.felix.scr.impl.manager.DependencyManager.ungetService(DependencyManager.java:900)
  org.apache.felix.scr.impl.manager.DependencyManager.unbind(DependencyManager.java:1138)
  org.apache.felix.scr.impl.manager.DependencyManager.close(DependencyManager.java:970)
  org.apache.felix.scr.impl.manager.ImmediateComponentManager.disposeImplementationObject(ImmediateComponentManager.java:276)
  org.apache.felix.scr.impl.manager.ImmediateComponentManager.deleteComponent(ImmediateComponentManager.java:148)
  org.apache.felix.scr.impl.manager.AbstractComponentManager$Active.ungetService(AbstractComponentManager.java:1718)
  org.apache.felix.scr.impl.manager.ImmediateComponentManager.ungetService(ImmediateComponentManager.java:695)
  org.apache.felix.framework.ServiceRegistrationImpl.ungetFactoryUnchecked(ServiceRegistrationImpl.java:349)
  org.apache.felix.framework.ServiceRegistrationImpl.ungetService(ServiceRegistrationImpl.java:258)
  org.apache.felix.framework.ServiceRegistry.ungetService(ServiceRegistry.java:389)
>>>>>>>>inside the lock  org.apache.felix.framework.ServiceRegistry.unregisterService(ServiceRegistry.java:158)
  org.apache.felix.framework.ServiceRegistrationImpl.unregister(ServiceRegistrationImpl.java:127)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.unregisterComponentService(AbstractComponentManager.java:779)
  org.apache.felix.scr.impl.manager.AbstractComponentManager$State.doDeactivate(AbstractComponentManager.java:1387)
  org.apache.felix.scr.impl.manager.AbstractComponentManager$Satisfied.deactivate(AbstractComponentManager.java:1665)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.deactivateInternal(AbstractComponentManager.java:635)
  org.apache.felix.scr.impl.manager.DependencyManager.serviceRemoved(DependencyManager.java:375)
  org.apache.felix.scr.impl.manager.DependencyManager.serviceChanged(DependencyManager.java:217)
  org.apache.felix.framework.util.EventDispatcher.invokeServiceListenerCallback(EventDispatcher.java:932)
  org.apache.felix.framework.util.EventDispatcher.fireEventImmediately(EventDispatcher.java:793)
  org.apache.felix.framework.util.EventDispatcher.fireServiceEvent(EventDispatcher.java:543)
  org.apache.felix.framework.Felix.fireServiceEvent(Felix.java:4260)
  org.apache.felix.framework.Felix.access$000(Felix.java:74)
  org.apache.felix.framework.Felix$1.serviceChanged(Felix.java:390)
  org.apache.felix.framework.ServiceRegistry.unregisterService(ServiceRegistry.java:148)
  org.apache.felix.framework.ServiceRegistrationImpl.unregister(ServiceRegistrationImpl.java:127)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.unregisterComponentService(AbstractComponentManager.java:779)
  org.apache.felix.scr.impl.manager.AbstractComponentManager$State.doDeactivate(AbstractComponentManager.java:1387)
  org.apache.felix.scr.impl.manager.AbstractComponentManager$Disabled.deactivate(AbstractComponentManager.java:1461)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.deactivateInternal(AbstractComponentManager.java:635)
  org.apache.felix.scr.impl.manager.AbstractComponentManager$2.run(AbstractComponentManager.java:435)
  org.apache.felix.scr.impl.ComponentActorThread.run(ComponentActorThread.java:98)
  java.lang.Thread.run(Thread.java:680)

ThreadId: 67 : name: pool-1-thread-49 State: BLOCKED
  LockInfo: org.apache.felix.framework.ServiceRegistry@26d66426 LockOwnerId: 16 LockOwnerName: SCR Component Actor
  org.apache.felix.framework.ServiceRegistry.getServiceReferences(ServiceRegistry.java:204)
  org.apache.felix.framework.Felix.getServiceReferences(Felix.java:3310)
  org.apache.felix.framework.Felix.getAllowedServiceReferences(Felix.java:3383)
  org.apache.felix.framework.BundleContextImpl.getServiceReferences(BundleContextImpl.java:432)
  org.apache.felix.scr.impl.manager.DependencyManager.getFrameworkServiceReferences(DependencyManager.java:658)
  org.apache.felix.scr.impl.manager.DependencyManager.getFrameworkServiceReferences(DependencyManager.java:634)
  org.apache.felix.scr.impl.manager.DependencyManager.enable(DependencyManager.java:551)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.enableDependencyManagers(AbstractComponentManager.java:1061)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.access$600(AbstractComponentManager.java:63)
  org.apache.felix.scr.impl.manager.AbstractComponentManager$Disabled.enable(AbstractComponentManager.java:1445)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.enableInternal(AbstractComponentManager.java:625)
  org.apache.felix.scr.impl.manager.AbstractComponentManager.enable(AbstractComponentManager.java:358)
  org.apache.felix.scr.impl.config.ImmediateComponentHolder.enableComponents(ImmediateComponentHolder.java:384)
  org.apache.felix.scr.impl.BundleComponentActivator.enableComponent(BundleComponentActivator.java:395)
  org.apache.felix.scr.impl.manager.ComponentContextImpl.enableComponent(ComponentContextImpl.java:101)
  test.scr.Main$EnableManager$1.run(Main.java:56)
  java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
  java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
  java.lang.Thread.run(Thread.java:680)

Issue Links

• blocks: FELIX-3680 Exceptions in SCR using concurrent service activation/deactivation
• is duplicated by: FELIX-3746 Deadlock around SCR AbstractComponentManager and DelayedComponentManager
• is duplicated by: FELIX-4190 The framework should not hold any lock while calling ServiceFactory#unget