7 Replies Latest reply on Sep 16, 2009 11:55 PM by Tolga Tarhan

    Performance issue: VFSClassLoaderPolicy uses URL.hashCode(),

    Tolga Tarhan Newbie

      I believe I have found a performance issue in JBoss AS 5.1.0.GA caused by the use of a ConcurrentHashMap with URL objects as the hash key. The offending usage is in VFSClassLoaderPolicy, in a member field named manifestCache. The field manifestCache is initialized as ConcurrentHashMap<URL, Manifest>();

      The underlying issue is that URL.hashCode() is a non-trivial operation, often requiring a DNS lookup. This DNS lookup can take a long time to timeout, adding up to 1-minute to the startup time of the application server .The issue is also encountered during runtime if certain class loader features are used (ie. getResource), causing up to a 1-minute delay when such features are used.

      The DNS lookups will never resolve in most cases, as the URL objects in question are usually in the form of:

      vfsmemory:aa15-xok7cr-fznfpulr-1-fznfpxto-7...

      A simple fix is to use the String returned form URL.toString() as the map key.

      Can anyone confirm that this in in fact a bug? The delays can be a significant issue, especially the runtime delays.

      Backtrace showing URL.hashCode causing a DNS lookup when used in ConcurrentHashMap from VFSClassLoaderPolicy:

       Inet6AddressImpl.lookupAllHostAddr(String) line: not available [native method]
       InetAddress$1.lookupAllHostAddr(String) line: 849
       InetAddress.getAddressFromNameService(String, InetAddress) line: 1200
       InetAddress.getAllByName0(String, InetAddress, boolean) line: 1153
       InetAddress.getAllByName(String, InetAddress) line: 1083
       InetAddress.getAllByName(String) line: 1019
       InetAddress.getByName(String) line: 969
       Handler(URLStreamHandler).getHostAddress(URL) line: 420
       Handler(URLStreamHandler).hashCode(URL) line: 337
       URL.hashCode() line: 857 [local variables unavailable]
       ConcurrentHashMap<K,V>.get(Object) line: 768
       VFSClassLoaderPolicy.getClassPackageInformation(String, String) line: 606
       BaseClassLoader.definePackage(String, URL) line: 722
       BaseClassLoader$2.run() line: 567
       BaseClassLoader$2.run() line: 532
       AccessController.doPrivileged(PrivilegedAction<T>, AccessControlContext) line: not available [native method]
       BaseClassLoader.loadClassLocally(String, boolean) line: 530
       BaseClassLoader.loadClassLocally(String) line: 507
       DelegateLoader(BaseDelegateLoader).loadClass(String) line: 134
       ClassLoadingTask$ThreadTask.run() line: 452
       ClassLoaderManager.nextTask(Thread, ClassLoadingTask) line: 251
       ClassLoaderManager.process(Thread, ClassLoadingTask) line: 150
       ClassLoaderDomain(BaseClassLoaderDomain).loadClass(BaseClassLoader, String, boolean) line: 265
       ClassLoaderDomain(BaseClassLoaderDomain).loadClass(BaseClassLoader, String) line: 1119
       BaseClassLoader.loadClassFromDomain(String, boolean) line: 798
       BaseClassLoader.loadClass(String, boolean) line: 441
       BaseClassLoader(ClassLoader).loadClass(String) line: 252
       ToClassInvoker.toClass(ToClassInvokerPoolReference, CtClass, String, ClassLoader, ProtectionDomain) line: 88
       JBossClDelegatingClassPool.toClass(CtClass, ClassLoader, ProtectionDomain) line: 81
       CtNewClass(CtClass).toClass(ClassLoader, ProtectionDomain) line: 1094
       TransformerCommon$ToClassAction$2.toClass(CtClass, ClassLoader, ProtectionDomain) line: 331
       TransformerCommon.toClass(CtClass, ClassLoader, ProtectionDomain) line: 139
       ProxyFactory.createProxyClass(ClassLoader, ProxyMixin[], Class<?>[]) line: 126
       ProxyFactory.createInterfaceProxy(GUID, ClassLoader, Class<?>[], ProxyMixin[], InstanceAdvisor) line: 96
       ProxyFactory.createInterfaceProxy(GUID, ClassLoader, Class<?>[]) line: 86
       Remoting.createRemoteProxy(Object, ClassLoader, Class[], InvokerLocator, List<Interceptor>, String) line: 102
       ManagedOperationProxyFactory.createDispatcherProxy() line: 203
       ManagedOperationProxyFactory.start() line: 109
       NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]
       NativeMethodAccessorImpl.invoke(Object, Object[]) line: 39
       DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 25
       Method.invoke(Object, Object...) line: 597
       ReflectionUtils.invoke(Method, Object, Object[]) line: 59
       ReflectMethodInfoImpl.invoke(Object, Object[]) line: 150
       BasicMethodJoinPoint.dispatch() line: 66
       KernelControllerContextAction$JoinpointDispatchWrapper.execute() line: 241
       KernelControllerContextAction$JoinpointDispatchWrapper(ExecutionWrapper).execute(AccessControlContext) line: 47
       KernelControllerContextAction.dispatchExecutionWrapper(KernelControllerContext, ExecutionWrapper) line: 109
       KernelControllerContextAction.dispatchJoinPoint(KernelControllerContext, Joinpoint) line: 70
       StartStopLifecycleAction(LifecycleAction).installActionInternal(KernelControllerContext) line: 221
       StartStopLifecycleAction(InstallsAwareAction).installAction(KernelControllerContext) line: 54
       StartStopLifecycleAction(InstallsAwareAction).installAction(ControllerContext) line: 42
       StartStopLifecycleAction(SimpleControllerContextAction<T>).simpleInstallAction(T) line: 62
       StartStopLifecycleAction(AccessControllerContextAction<S,T>).install(ControllerContext) line: 71
       KernelControllerContextActions(AbstractControllerContextActions).install(ControllerContext, ControllerState, ControllerState) line: 51
       AbstractKernelControllerContext(AbstractControllerContext).install(ControllerState, ControllerState) line: 348
       AbstractKernelController(AbstractController).install(ControllerContext, ControllerState, ControllerState) line: 1631
       AbstractKernelController(AbstractController).incrementState(ControllerContext, boolean) line: 934
       AbstractKernelController(AbstractController).resolveContexts(ControllerState, ControllerState, boolean) line: 1082
       AbstractKernelController(AbstractController).resolveContexts(boolean) line: 984
       AbstractKernelController(AbstractController).install(ControllerContext, boolean) line: 774
       AbstractKernelController(AbstractController).install(ControllerContext) line: 540
       ServiceController.doInstall(KernelController, ServiceControllerContext) line: 670
       ServiceController.register(ObjectName, Collection<ObjectName>, boolean, Object) line: 373
       ServiceControllerRegistrationLifecycleCallback.install(ControllerContext) line: 104
       NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]
       NativeMethodAccessorImpl.invoke(Object, Object[]) line: 39
       DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 25
       Method.invoke(Object, Object...) line: 597
       ReflectionUtils.invoke(Method, Object, Object[]) line: 59
       ReflectMethodInfoImpl.invoke(Object, Object[]) line: 150
       BasicMethodJoinPoint.dispatch() line: 66
       AbstractBeanInfo.invoke(Object, String, String[], Object[]) line: 300
       AbstractKernelControllerContext.invoke(String, Object[], String[]) line: 286
       AbstractLifecycleCallbackItem.install(ControllerContext) line: 87
       AbstractKernelController(AbstractController).handleLifecycleCallbacks(ControllerContext, ControllerState, boolean) line: 1568
       AbstractKernelController(AbstractController).handleInstallLifecycleCallbacks(ControllerContext, ControllerState) line: 1533
       AbstractKernelController(AbstractController).incrementState(ControllerContext, boolean) line: 943
       AbstractKernelController(AbstractController).resolveContexts(ControllerState, ControllerState, boolean) line: 1082
       AbstractKernelController(AbstractController).resolveContexts(boolean) line: 984
       AbstractKernelController(AbstractController).change(ControllerContext, ControllerState, boolean) line: 822
       AbstractKernelController(AbstractController).change(ControllerContext, ControllerState) line: 553
       ServiceController.doChange(KernelController, ServiceControllerContext, ControllerState, String) line: 688
       ServiceController.start(ObjectName) line: 460
       ServiceControllerStartStopLifecycleCallback.install(ControllerContext) line: 44
       NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]
       NativeMethodAccessorImpl.invoke(Object, Object[]) line: 39
       DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 25
       Method.invoke(Object, Object...) line: 597
       ReflectionUtils.invoke(Method, Object, Object[]) line: 59
       ReflectMethodInfoImpl.invoke(Object, Object[]) line: 150
       BasicMethodJoinPoint.dispatch() line: 66
       AbstractBeanInfo.invoke(Object, String, String[], Object[]) line: 300
       AbstractKernelControllerContext.invoke(String, Object[], String[]) line: 286
       AbstractLifecycleCallbackItem.install(ControllerContext) line: 87
       AbstractKernelController(AbstractController).handleLifecycleCallbacks(ControllerContext, ControllerState, boolean) line: 1568
       AbstractKernelController(AbstractController).handleInstallLifecycleCallbacks(ControllerContext, ControllerState) line: 1533
       AbstractKernelController(AbstractController).incrementState(ControllerContext, boolean) line: 943
       AbstractKernelController(AbstractController).resolveContexts(ControllerState, ControllerState, boolean) line: 1082
       AbstractKernelController(AbstractController).resolveContexts(boolean) line: 984
       AbstractKernelController(AbstractController).install(ControllerContext, boolean) line: 774
       AbstractKernelController(AbstractController).install(ControllerContext) line: 540
       BeanMetaDataDeployer.deploy(DeploymentUnit, BeanMetaData) line: 121
       BeanMetaDataDeployer.deploy(DeploymentUnit, Object) line: 51
       BeanMetaDataDeployer(AbstractSimpleRealDeployer<T>).internalDeploy(DeploymentUnit) line: 62
       BeanMetaDataDeployer(AbstractRealDeployer).deploy(DeploymentUnit) line: 50
       DeployerWrapper.deploy(DeploymentUnit) line: 171
       DeployersImpl.doDeploy(Deployer, DeploymentUnit) line: 1439
       DeployersImpl.doInstallParentFirst(Deployer, DeploymentContext) line: 1157
       DeployersImpl.doInstallParentFirst(Deployer, DeploymentContext) line: 1178
       DeployersImpl.install(ControllerContext, ControllerState, ControllerState) line: 1098
       DeploymentControllerContext(AbstractControllerContext).install(ControllerState, ControllerState) line: 348
       AbstractKernelController(AbstractController).install(ControllerContext, ControllerState, ControllerState) line: 1631
       AbstractKernelController(AbstractController).incrementState(ControllerContext, boolean) line: 934
       AbstractKernelController(AbstractController).resolveContexts(ControllerState, ControllerState, boolean) line: 1082
       AbstractKernelController(AbstractController).resolveContexts(boolean) line: 984
       AbstractKernelController(AbstractController).change(ControllerContext, ControllerState, boolean) line: 822
       AbstractKernelController(AbstractController).change(ControllerContext, ControllerState) line: 553
       DeployersImpl.process(List<DeploymentContext>, List<DeploymentContext>) line: 781
       MainDeployerImpl.process() line: 702
       MainDeployerAdapter.process() line: 117
       ProfileDeployAction.install(Profile) line: 70
       ProfileDeployAction(AbstractProfileAction).install(ProfileContext) line: 53
       AbstractProfileService.install(ControllerContext, ControllerState, ControllerState) line: 361
       ProfileContext(AbstractControllerContext).install(ControllerState, ControllerState) line: 348
       ScopedProfileServiceController(AbstractController).install(ControllerContext, ControllerState, ControllerState) line: 1631
       ScopedProfileServiceController(AbstractController).incrementState(ControllerContext, boolean) line: 934
       ScopedProfileServiceController(AbstractController).resolveContexts(ControllerState, ControllerState, boolean) line: 1082
       ScopedProfileServiceController(AbstractController).resolveContexts(boolean) line: 984
       ScopedProfileServiceController(AbstractController).change(ControllerContext, ControllerState, boolean) line: 822
       ScopedProfileServiceController(AbstractController).change(ControllerContext, ControllerState) line: 553
       AbstractProfileService.activateProfile(ProfileKey) line: 306
       ProfileServiceBootstrap.start(Server) line: 271
       ServerImpl(AbstractServerImpl).start() line: 461
       Main.boot(String[]) line: 221
       Main$1.run() line: 556
       Thread.run() line: 619