High CPU or many blocked threads in BaseClassLoader.getResourcesLocally

Issue

• After migrating to EAP 5, we see high CPU and the high CPU threads all appear to be executing BaseClassLoader.getResourcesLocally:

      Thread: ajp-0.0.0.0-8009-1 : priority:5, demon:true, threadId:408, threadState:RUNNABLE
          java.io.WinNTFileSystem.getLastModifiedTime(Native Method)
          java.io.File.lastModified(File.java:826)
          org.jboss.virtual.plugins.context.zip.ZipFileWrapper.getLastModified(ZipFileWrapper.java:140)
          org.jboss.virtual.plugins.context.zip.ZipWrapper.hasBeenModified(ZipWrapper.java:71)
          org.jboss.virtual.plugins.context.zip.ZipEntryContext.checkIfModified(ZipEntryContext.java:788)
          - locked <0x6c691ec4> (a org.jboss.virtual.plugins.context.zip.ZipEntryContext)
          org.jboss.virtual.plugins.context.zip.ZipEntryContext.getChild(ZipEntryContext.java:830)
          org.jboss.virtual.plugins.context.zip.ZipEntryHandler.createChildHandler(ZipEntryHandler.java:195)
          org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.structuredFindChild(AbstractVirtualFileHandler.java:690)
          org.jboss.virtual.plugins.context.zip.ZipEntryHandler.getChild(ZipEntryHandler.java:169)
          org.jboss.virtual.plugins.context.DelegatingHandler.getChild(DelegatingHandler.java:107)
          org.jboss.virtual.VirtualFile.getChild(VirtualFile.java:492)
          org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.getResources(VFSClassLoaderPolicy.java:525)
          org.jboss.classloader.spi.base.BaseClassLoader$4.run(BaseClassLoader.java:755)
          java.security.AccessController.doPrivileged(Native Method)
          org.jboss.classloader.spi.base.BaseClassLoader.getResourcesLocally(BaseClassLoader.java:751)
          org.jboss.classloader.spi.base.BaseClassLoader.getResourcesLocally(BaseClassLoader.java:731)
          org.jboss.classloader.spi.base.BaseClassLoaderDomain.getResources(BaseClassLoaderDomain.java:520)
          org.jboss.classloader.spi.base.BaseClassLoaderDomain.getResources(BaseClassLoaderDomain.java:1175)
          org.jboss.classloader.spi.base.BaseClassLoader.loadResources(BaseClassLoader.java:554)
          org.jboss.classloader.spi.base.BaseClassLoader.findResources(BaseClassLoader.java:539)
          java.lang.ClassLoader.getResources(ClassLoader.java:1040)
  

• We have many threads blocking on the same ZipEntryContext objects through calls to BaseClassLoader.getResourcesLocally():

      Thread: ajp-0.0.0.0-8009-1 : priority:5, demon:true, threadId:409, threadState:BLOCKED
  
  
      - waiting to lock <0xe01e3acba3534528> (a org.jboss.virtual.plugins.context.zip.ZipEntryContext)
       at org.jboss.virtual.plugins.context.zip.ZipEntryContext.getChild(ZipEntryContext.java:830)
       at org.jboss.virtual.plugins.context.zip.ZipEntryHandler.createChildHandler(ZipEntryHandler.java:195)
       at org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.structuredFindChild(AbstractVirtualFileHandler.java:690)
       at org.jboss.virtual.plugins.context.zip.ZipEntryHandler.getChild(ZipEntryHandler.java:169)
       at org.jboss.virtual.plugins.context.DelegatingHandler.getChild(DelegatingHandler.java:107)
       at org.jboss.virtual.VirtualFile.getChild(VirtualFile.java:492)
       at org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.getResources(VFSClassLoaderPolicy.java:525)
       at org.jboss.classloader.spi.base.BaseClassLoader$4.run(BaseClassLoader.java:755)
       at java.security.AccessController.doPrivileged(Native Method)
       at org.jboss.classloader.spi.base.BaseClassLoader.getResourcesLocally(BaseClassLoader.java:751)
       at org.jboss.classloader.spi.base.BaseClassLoader.getResourcesLocally(BaseClassLoader.java:731)
       at org.jboss.classloader.spi.base.BaseDelegateLoader.getResources(BaseDelegateLoader.java:152)
       at org.jboss.classloader.spi.filter.FilteredDelegateLoader.getResources(FilteredDelegateLoader.java:160)
       at org.jboss.classloader.spi.base.BaseClassLoaderDomain.getResourcesFromExports(BaseClassLoaderDomain.java:791)
       at org.jboss.classloader.spi.base.BaseClassLoaderDomain.getResources(BaseClassLoaderDomain.java:507)
       at org.jboss.classloader.spi.base.BaseClassLoaderDomain.getResources(BaseClassLoaderDomain.java:1175)
       at org.jboss.classloader.spi.base.BaseClassLoader.loadResources(BaseClassLoader.java:554)
       at org.jboss.classloader.spi.base.BaseClassLoader.findResources(BaseClassLoader.java:539)
       at java.lang.ClassLoader.getResources(ClassLoader.java:1041)