[jboss-jira] [JBoss JIRA] (WFLY-2496) Concurrent access to ModuleSpecification causes race condition

[Jozef Hartinger (JIRA)]

Jozef Hartinger created WFLY-2496:
-------------------------------------

             Summary: Concurrent access to ModuleSpecification causes race condition
                 Key: WFLY-2496
                 URL: https://issues.jboss.org/browse/WFLY-2496
             Project: WildFly
          Issue Type: Bug
      Security Level: Public (Everyone can see)
          Components: Server
    Affects Versions: 8.0.0.Beta1
            Reporter: Jozef Hartinger
            Assignee: Jason Greene
            Priority: Critical
             Fix For: 8.0.0.CR1


[ModuleSpecification|https://github.com/wildfly/wildfly/blob/master/server/src/main/java/org/jboss/as/server/deployment/module/ModuleSpecification.java] does not use any form of synchronization to protect its mutable state yet may be used from multiple threads in multi-module deployment when a DeploymentUnitProcessor touches ModuleSpecification of a different deployment unit which is processed at that moment.

Here is an example of such access: https://github.com/wildfly/wildfly/blob/master/jsf/subsystem/src/main/java/org/jboss/as/jsf/deployment/JSFDependencyProcessor.java#L93

Here's how I think this problem manifests:

{noformat}
Caused by: java.lang.NullPointerException
        at org.jboss.as.server.deployment.module.ModuleSpecProcessor.createDependencies(ModuleSpecProcessor.java:284) [wildfly-server-8.0.0.Beta2-SNAPSHOT.jar:8.0.0.Beta2-SNAPSHOT]
        at org.jboss.as.server.deployment.module.ModuleSpecProcessor.createModuleService(ModuleSpecProcessor.java:220) [wildfly-server-8.0.0.Beta2-SNAPSHOT.jar:8.0.0.Beta2-SNAPSHOT]
        at org.jboss.as.server.deployment.module.ModuleSpecProcessor.deployModuleSpec(ModuleSpecProcessor.java:125) [wildfly-server-8.0.0.Beta2-SNAPSHOT.jar:8.0.0.Beta2-SNAPSHOT]
        at org.jboss.as.server.deployment.module.ModuleSpecProcessor.deploy(ModuleSpecProcessor.java:88) [wildfly-server-8.0.0.Beta2-SNAPSHOT.jar:8.0.0.Beta2-SNAPSHOT]
        at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:159) [wildfly-server-8.0.0.Beta2-SNAPSHOT.jar:8.0.0.Beta2-SNAPSHOT]
        ... 5 more
{noformat}

and here's my attempt to verify concurrent access by changing the code slightly to deadlock on concurrent access: 
{noformat}
"MSC service thread 1-6":
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000f742ba28> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:867)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1197)
        at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:214)
        at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:290)
        at org.jboss.as.server.deployment.module.ModuleSpecification.foo(ModuleSpecification.java:170)
        at org.jboss.as.server.deployment.module.ModuleSpecification.addSystemDependency(ModuleSpecification.java:121)
        at org.jboss.as.jsf.deployment.JSFDependencyProcessor.addJSFAPI(JSFDependencyProcessor.java:115)
        at org.jboss.as.jsf.deployment.JSFDependencyProcessor.deploy(JSFDependencyProcessor.java:93)
        at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:159)
        - locked <0x00000000f69a8e88> (a org.jboss.as.server.deployment.DeploymentUnitPhaseService)
        at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1944)
        at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1877)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:744)
"MSC service thread 1-3":
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000f742ba58> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:867)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1197)
        at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:214)
        at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:290)
        at org.jboss.as.server.deployment.module.ModuleSpecification.foo(ModuleSpecification.java:175)
        at org.jboss.as.server.deployment.module.ModuleSpecification.addSystemDependency(ModuleSpecification.java:121)
        at org.jboss.as.jsf.deployment.JSFDependencyProcessor.addJSFAPI(JSFDependencyProcessor.java:115)
        at org.jboss.as.jsf.deployment.JSFDependencyProcessor.deploy(JSFDependencyProcessor.java:93)
        at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:159)
        - locked <0x00000000f6782960> (a org.jboss.as.server.deployment.DeploymentUnitPhaseService)
        at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1944)
        at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1877)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:744)
{noformat}

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