From a8d0fefc52c821169e1c9d7be41cdeb75456dd64 Mon Sep 17 00:00:00 2001 From: Andrew Azores Date: Wed, 16 Oct 2013 13:13:19 -0400 Subject: Resolve multiple-applet deadlock issue in JNLPClassLoader New lock used for synchronizing JNLPClassLoader#loadClass(String) to avoid deadlock condition when multiple applets are being loaded simultaneously. Regression test included. * netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java: (loadClassLock) private member for locking of loadClass method. (loadClass) synchronizes using new lock rather than instance intrinsic lock to avoid RH976833 deadlock * tests/reproducers/custom/JNLPClassLoaderDeadlock/testcases/JNLPClassLoaderDeadlockTest.java: new test for multiple applet deadlock condition * tests/reproducers/custom/JNLPClassLoaderDeadlock/resources/JNLPClassLoaderDeadlock.html: same * tests/reproducers/custom/JNLPClassLoaderDeadlock/srcs/JNLPClassLoaderDeadlock_1.java: same * tests/reproducers/custom/JNLPClassLoaderDeadlock/srcs/JNLPClassLoaderDeadlock_2.java: same * tests/reproducers/custom/JNLPClassLoaderDeadlock/srcs/Makefile: same --- .../sourceforge/jnlp/runtime/JNLPClassLoader.java | 135 +++++++++++---------- 1 file changed, 73 insertions(+), 62 deletions(-) (limited to 'netx/net/sourceforge/jnlp') diff --git a/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java b/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java index c387b35..e7a080e 100644 --- a/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java +++ b/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java @@ -205,6 +205,16 @@ public class JNLPClassLoader extends URLClassLoader { */ private int useCount = 0; + /* This Object is used as a lock on the loadClass(String) method. This method should not + * be entered by multiple threads simultaneously. This Object should be used for no other + * purpose than synchronizing the body of the loadClass(String) method. The intrinsic instance + * lock is not suitable for this purpose or else deadlock may occur. + * + * See bug RH976833 and the mailing list archive discussion: + * http://mail.openjdk.java.net/pipermail/distro-pkg-dev/2013-September/024536.html + */ + private final Object loadClassLock = new Object(); + /** * Create a new JNLPClassLoader from the specified file. * @@ -1410,88 +1420,89 @@ public class JNLPClassLoader extends URLClassLoader { * classloader, or one of the classloaders for the JNLP file's * extensions. */ - public synchronized Class loadClass(String name) throws ClassNotFoundException { + public Class loadClass(String name) throws ClassNotFoundException { + synchronized (loadClassLock) { + Class result = findLoadedClassAll(name); - Class result = findLoadedClassAll(name); - - // try parent classloader - if (result == null) { - try { - ClassLoader parent = getParent(); - if (parent == null) - parent = ClassLoader.getSystemClassLoader(); + // try parent classloader + if (result == null) { + try { + ClassLoader parent = getParent(); + if (parent == null) + parent = ClassLoader.getSystemClassLoader(); - return parent.loadClass(name); - } catch (ClassNotFoundException ex) { + return parent.loadClass(name); + } catch (ClassNotFoundException ex) { + } } - } - // filter out 'bad' package names like java, javax - // validPackage(name); + // filter out 'bad' package names like java, javax + // validPackage(name); - // search this and the extension loaders - if (result == null) { - try { - result = loadClassExt(name); - } catch (ClassNotFoundException cnfe) { - // Not found in external loader either - - // Look in 'Class-Path' as specified in the manifest file + // search this and the extension loaders + if (result == null) { try { - for (String classpath: classpaths) { - JARDesc desc; - try { - URL jarUrl = new URL(file.getCodeBase(), classpath); - desc = new JARDesc(jarUrl, null, null, false, true, false, true); - } catch (MalformedURLException mfe) { - throw new ClassNotFoundException(name, mfe); - } - addNewJar(desc); - } - result = loadClassExt(name); - return result; - } catch (ClassNotFoundException cnfe1) { - OutputController.getLogger().log(cnfe1); - } - - // As a last resort, look in any available indexes - - // Currently this loads jars directly from the site. We cannot cache it because this - // call is initiated from within the applet, which does not have disk read/write permissions - for (JarIndex index : jarIndexes) { - // Non-generic code in sun.misc.JarIndex - @SuppressWarnings("unchecked") - LinkedList jarList = index.get(name.replace('.', '/')); + } catch (ClassNotFoundException cnfe) { + // Not found in external loader either - if (jarList != null) { - for (String jarName : jarList) { + // Look in 'Class-Path' as specified in the manifest file + try { + for (String classpath : classpaths) { JARDesc desc; try { - desc = new JARDesc(new URL(file.getCodeBase(), jarName), - null, null, false, true, false, true); + URL jarUrl = new URL(file.getCodeBase(), classpath); + desc = new JARDesc(jarUrl, null, null, false, true, false, true); } catch (MalformedURLException mfe) { - throw new ClassNotFoundException(name); - } - try { - addNewJar(desc); - } catch (Exception e) { - OutputController.getLogger().log(e); + throw new ClassNotFoundException(name, mfe); } + addNewJar(desc); } - // If it still fails, let it error out result = loadClassExt(name); + return result; + } catch (ClassNotFoundException cnfe1) { + OutputController.getLogger().log(cnfe1); + } + + // As a last resort, look in any available indexes + + // Currently this loads jars directly from the site. We cannot cache it because this + // call is initiated from within the applet, which does not have disk read/write permissions + for (JarIndex index : jarIndexes) { + // Non-generic code in sun.misc.JarIndex + @SuppressWarnings("unchecked") + LinkedList jarList = index.get(name.replace('.', '/')); + + if (jarList != null) { + for (String jarName : jarList) { + JARDesc desc; + try { + desc = new JARDesc(new URL(file.getCodeBase(), jarName), + null, null, false, true, false, true); + } catch (MalformedURLException mfe) { + throw new ClassNotFoundException(name); + } + try { + addNewJar(desc); + } catch (Exception e) { + OutputController.getLogger().log(e); + } + } + + // If it still fails, let it error out + result = loadClassExt(name); + } } } } - } - if (result == null) { - throw new ClassNotFoundException(name); - } + if (result == null) { + throw new ClassNotFoundException(name); + } - return result; + return result; + } } /** -- cgit v1.2.3