Deadlock when stopping and restarting the URLDeploymentScanner

There is a deadlock when you stop and restart the URLDeploymentScanner
if the background thread does not stop immediately, e.g. it is busy deploying something.

The URLDeploymentScanner's unstopped background thread can deadlock with at least the
service controller when there is an attempt to restart it.

Here is an example deadlock.

Java stack information for the threads listed above:
===================================================
"RMI TCP Connection(21)-172.16.18.92":
at org.jboss.deployment.scanner.URLDeploymentScanner.scan(URLDeploymentScanner.java:375)

• waiting to lock <0xabcfd358> (a org.jboss.deployment.scanner.URLDeploymentScanner)
  at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.doScan(AbstractDeploymentScanner.java:204)
  at org.jboss.deployment.scanner.AbstractDeploymentScanner.startService(AbstractDeploymentScanner.java:277)
• locked <0xabd607b8> (a org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread)
  at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:272)
  at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:222)
  at sun.reflect.GeneratedMethodAccessor71.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
  at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:72)
  at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:249)
  at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
  at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:897)
  at $Proxy0.start(Unknown Source)
  at org.jboss.system.ServiceController.start(ServiceController.java:418)
• locked <0xabafa6a0> (a org.jboss.system.ServiceController)
  at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
  at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:72)
  at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:249)
  at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
  at org.jboss.system.ServiceMBeanSupport.start(ServiceMBeanSupport.java:171)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
  at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:72)
  at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:249)
  at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at org.jboss.jmx.connector.invoker.InvokerAdaptorService.invoke(InvokerAdaptorService.java:251)
  at sun.reflect.GeneratedMethodAccessor81.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
  at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
  at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:121)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:74)
  at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:127)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:74)
  at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:249)
  at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
  at org.jboss.invocation.jrmp.server.JRMPProxyFactory.invoke(JRMPProxyFactory.java:164)
  at sun.reflect.GeneratedMethodAccessor80.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
  at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:72)
  at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:249)
  at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
  at org.jboss.invocation.jrmp.server.JRMPInvoker$MBeanServerAction.invoke(JRMPInvoker.java:805)
  at org.jboss.invocation.jrmp.server.JRMPInvoker.invoke(JRMPInvoker.java:406)
  at sun.reflect.GeneratedMethodAccessor79.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:261)
  at sun.rmi.transport.Transport$1.run(Transport.java:148)
  at java.security.AccessController.doPrivileged(Native Method)
  at sun.rmi.transport.Transport.serviceCall(Transport.java:144)
  at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:460)
  at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:701)
  at java.lang.Thread.run(Thread.java:534)
  "ScannerThread":
  at org.jboss.system.ServiceController.create(ServiceController.java:275)
• waiting to lock <0xabafa6a0> (a org.jboss.system.ServiceController)
  at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
  at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:72)
  at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:249)
  at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
  at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:177)
  at $Proxy20.create(Unknown Source)
  at org.jboss.deployment.EARDeployer.create(EARDeployer.java:284)
  at org.jboss.deployment.MainDeployer.create(MainDeployer.java:918)
  at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:774)
  at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:738)
  at sun.reflect.GeneratedMethodAccessor51.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at java.lang.reflect.Method.invoke(Method.java:324)
  at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141)
  at org.jboss.mx.server.Invocation.dispatch(Invocation.java:80)
  at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:121)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:74)
  at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:127)
  at org.jboss.mx.server.Invocation.invoke(Invocation.java:74)
  at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:249)
  at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:644)
  at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:177)
  at $Proxy8.deploy(Unknown Source)
  at org.jboss.deployment.scanner.URLDeploymentScanner.deploy(URLDeploymentScanner.java:325)
  at org.jboss.deployment.scanner.URLDeploymentScanner.scan(URLDeploymentScanner.java:501)
• locked <0xabcfd358> (a org.jboss.deployment.scanner.URLDeploymentScanner)
  at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.doScan(AbstractDeploymentScanner.java:204)
  at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.loop(AbstractDeploymentScanner.java:215)
  at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.run(AbstractDeploymentScanner.java:194)

Found 1 deadlock.