Besides the AOP usage, the other major thing I'm seeing using hprof for sampling is the VFS usage by the classloader. I'll show some typical stacktraces: Not much we can do about the biggest one, since this is the JDK parsing the bytecode. The only way to reduce this, is the reduce the number of classes loaded. | java.lang.ClassLoader.defineClass1(ClassLoader.java:Unknown line) | java.lang.ClassLoader.defineClass(ClassLoader.java:620) | org.jboss.classloader.spi.base.BaseClassLoader.access$200(BaseClassLoader.java:62) | org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:504) | org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:464) | java.security.AccessController.doPrivileged(AccessController.java:Unknown line) | org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:462) | org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:439) | org.jboss.classloader.spi.base.BaseDelegateLoader.loadClass(BaseDelegateLoader.java:134) | org.jboss.classloader.spi.filter.FilteredDelegateLoader.loadClass(FilteredDelegateLoader.java:131) | Reading byte code from zip files | java.util.zip.Inflater.inflateBytes(Inflater.java:Unknown line) | java.util.zip.Inflater.inflate(Inflater.java:215) | java.util.zip.InflaterInputStream.read(InflaterInputStream.java:128) | java.io.FilterInputStream.read(FilterInputStream.java:90) | org.jboss.virtual.plugins.context.zip.ZipEntryInputStream.read(ZipEntryInputStream.java:112) | org.jboss.classloader.plugins.ClassLoaderUtils.loadByteCode(ClassLoaderUtils.java:150) | org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:475) | org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:464) | java.security.AccessController.doPrivileged(AccessController.java:Unknown line) | org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:462) | This looks inefficient, it is listing a parent directory when we do getChild | java.io.UnixFileSystem.checkAccess(UnixFileSystem.java:Unknown line) | java.io.File.canRead(File.java:660) | org.jboss.virtual.plugins.context.file.FileHandler.getChildren(FileHandler.java:161) | org.jboss.virtual.plugins.context.file.FileSystemContext.createVirtualFileHandler(FileSystemContext.java:337) | org.jboss.virtual.plugins.context.file.FileSystemContext.createVirtualFileHandler(FileSystemContext.java:256) | org.jboss.virtual.plugins.context.file.FileHandler.createChildHandler(FileHandler.java:224) | org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.structuredFindChild(AbstractVirtualFileHandler.java:509) | org.jboss.virtual.plugins.context.file.FileHandler.getChild(FileHandler.java:233) | org.jboss.virtual.VirtualFile.getChild(VirtualFile.java:427) | org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.findVirtualFileInfo(VFSClassLoaderPolicy.java:488) | Modified checking | java.io.UnixFileSystem.getLastModifiedTime(UnixFileSystem.java:Unknown line) | java.io.File.lastModified(File.java:795) | org.jboss.virtual.plugins.context.zip.ZipFileWrapper.getLastModified(ZipFileWrapper.java:140) | org.jboss.virtual.plugins.context.zip.ZipEntryContext.getLastModified(ZipEntryContext.java:682) | org.jboss.virtual.plugins.context.zip.ZipEntryHandler.getLastModified(ZipEntryHandler.java:92) | org.jboss.virtual.plugins.context.DelegatingHandler.getLastModified(DelegatingHandler.java:107) | org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.hasBeenModified(AbstractVirtualFileHandler.java:181) | org.jboss.virtual.plugins.context.file.FileHandler.getChildren(FileHandler.java:183) | org.jboss.virtual.plugins.context.file.FileSystemContext.createVirtualFileHandler(FileSystemContext.java:337) | org.jboss.virtual.plugins.context.file.FileSystemContext.createVirtualFileHandler(FileSystemContext.java:256) | I keep seeing this, not checked if it is a real inefficiency | org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.getLocalPathName(AbstractVirtualFileHandler.java:230) | org.jboss.virtual.plugins.context.zip.ZipEntryContext.isLeaf(ZipEntryContext.java:751) | org.jboss.virtual.plugins.context.zip.ZipEntryHandler.isLeaf(ZipEntryHandler.java:110) | org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.structuredFindChild(AbstractVirtualFileHandler.java:502) | org.jboss.virtual.plugins.context.zip.ZipEntryHandler.getChild(ZipEntryHandler.java:139) | org.jboss.virtual.plugins.context.DelegatingHandler.getChild(DelegatingHandler.java:93) | org.jboss.virtual.VirtualFile.getChild(VirtualFile.java:427) | org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.findVirtualFileInfo(VFSClassLoaderPolicy.java:488) | org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.findChild(VFSClassLoaderPolicy.java:452) | org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.getResource(VFSClassLoaderPolicy.java:385) | Similarly this | java.util.concurrent.ConcurrentHashMap$Segment.get(ConcurrentHashMap.java:334) | java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:731) | org.jboss.virtual.plugins.context.zip.ZipEntryContext.getRoot(ZipEntryContext.java:606) | org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.getLocalPathName(AbstractVirtualFileHandler.java:230) | org.jboss.virtual.plugins.context.zip.ZipEntryContext.isLeaf(ZipEntryContext.java:751) | org.jboss.virtual.plugins.context.zip.ZipEntryHandler.isLeaf(ZipEntryHandler.java:110) | org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.structuredFindChild(AbstractVirtualFileHandler.java:502) | org.jboss.virtual.plugins.context.zip.ZipEntryHandler.getChild(ZipEntryHandler.java:139) | org.jboss.virtual.plugins.context.DelegatingHandler.getChild(DelegatingHandler.java:93) | org.jboss.virtual.VirtualFile.getChild(VirtualFile.java:427) | I'm still seeing the PathTokenizer showing up | org.jboss.virtual.plugins.vfs.helpers.PathTokenizer.getTokens(PathTokenizer.java:97) | org.jboss.virtual.plugins.context.AbstractVirtualFileHandler.structuredFindChild(AbstractVirtualFileHandler.java:475) | org.jboss.virtual.plugins.context.zip.ZipEntryHandler.getChild(ZipEntryHandler.java:139) | org.jboss.virtual.plugins.context.DelegatingHandler.getChild(DelegatingHandler.java:93) | org.jboss.virtual.VirtualFile.getChild(VirtualFile.java:427) | org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.findVirtualFileInfo(VFSClassLoaderPolicy.java:488) | org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.findChild(VFSClassLoaderPolicy.java:452) | org.jboss.classloading.spi.vfs.policy.VFSClassLoaderPolicy.getResource(VFSClassLoaderPolicy.java:385) | org.jboss.classloader.spi.base.BaseClassLoader$3.run(BaseClassLoader.java:567) | org.jboss.classloader.spi.base.BaseClassLoader$3.run(BaseClassLoader.java:564) | View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4166367#... 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