There is 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.

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