changeset 2921:b444f86c4abe

6977738: Deadlock between java.lang.ClassLoader and java.util.Properties Reviewed-by: alanb, sherman, darcy, igor
author mchung
date Mon, 11 Oct 2010 20:22:27 -0700
parents 78bbe8fce2d4
children 33cf668cc160
files make/java/java/FILES_java.gmk src/share/classes/java/lang/Integer.java src/share/classes/java/lang/System.java src/share/classes/java/util/Properties.java src/share/classes/java/util/XMLUtils.java src/share/classes/java/util/zip/ZipFile.java src/share/classes/sun/jkernel/DownloadManager.java src/share/classes/sun/misc/BootClassLoaderHook.java src/share/classes/sun/misc/Launcher.java src/share/classes/sun/misc/VM.java test/java/lang/ClassLoader/deadlock/GetResource.java test/sun/misc/BootClassLoaderHook/TestHook.java
diffstat 12 files changed, 316 insertions(+), 158 deletions(-) [+]
line wrap: on
line diff
--- a/make/java/java/FILES_java.gmk	Mon Oct 11 10:55:04 2010 +0100
+++ b/make/java/java/FILES_java.gmk	Mon Oct 11 20:22:27 2010 -0700
@@ -465,14 +465,11 @@
     java/security/ProtectionDomain.java \
     java/net/URLClassLoader.java \
     java/net/URLConnection.java \
+    sun/misc/BootClassLoaderHook.java \
     sun/misc/Launcher.java \
     sun/misc/MetaIndex.java \
     sun/misc/URLClassPath.java \
     sun/misc/Version.java \
-    sun/net/www/protocol/jar/Handler.java \
-    sun/net/www/protocol/jar/JarURLConnection.java \
-    sun/net/www/protocol/file/Handler.java \
-    sun/net/www/protocol/file/FileURLConnection.java \
     sun/misc/FileURLMapper.java \
     sun/misc/MessageUtils.java \
     sun/misc/GC.java \
@@ -482,6 +479,10 @@
     sun/misc/JavaIOFileDescriptorAccess.java \
     sun/misc/JavaNioAccess.java \
     sun/misc/Perf.java \
-    sun/misc/PerfCounter.java
+    sun/misc/PerfCounter.java \
+    sun/net/www/protocol/jar/Handler.java \
+    sun/net/www/protocol/jar/JarURLConnection.java \
+    sun/net/www/protocol/file/Handler.java \
+    sun/net/www/protocol/file/FileURLConnection.java
 
 FILES_java = $(JAVA_JAVA_java)
--- a/src/share/classes/java/lang/Integer.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/java/lang/Integer.java	Mon Oct 11 20:22:27 2010 -0700
@@ -586,25 +586,13 @@
      * Cache to support the object identity semantics of autoboxing for values between
      * -128 and 127 (inclusive) as required by JLS.
      *
-     * The cache is initialized on first usage. During VM initialization the
-     * getAndRemoveCacheProperties method may be used to get and remove any system
-     * properites that configure the cache size. At this time, the size of the
-     * cache may be controlled by the -XX:AutoBoxCacheMax=<size> option.
+     * The cache is initialized on first usage.  The size of the cache
+     * may be controlled by the -XX:AutoBoxCacheMax=<size> option.
+     * During VM initialization, java.lang.Integer.IntegerCache.high property
+     * may be set and saved in the private system properties in the
+     * sun.misc.VM class.
      */
 
-    // value of java.lang.Integer.IntegerCache.high property (obtained during VM init)
-    private static String integerCacheHighPropValue;
-
-    static void getAndRemoveCacheProperties() {
-        if (!sun.misc.VM.isBooted()) {
-            Properties props = System.getProperties();
-            integerCacheHighPropValue =
-                (String)props.remove("java.lang.Integer.IntegerCache.high");
-            if (integerCacheHighPropValue != null)
-                System.setProperties(props);  // remove from system props
-        }
-    }
-
     private static class IntegerCache {
         static final int low = -128;
         static final int high;
@@ -613,6 +601,8 @@
         static {
             // high value may be configured by property
             int h = 127;
+            String integerCacheHighPropValue =
+                sun.misc.VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
             if (integerCacheHighPropValue != null) {
                 int i = parseInt(integerCacheHighPropValue);
                 i = Math.max(i, 127);
--- a/src/share/classes/java/lang/System.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/java/lang/System.java	Mon Oct 11 20:22:27 2010 -0700
@@ -53,7 +53,13 @@
  */
 public final class System {
 
-    /* First thing---register the natives */
+    /* register the natives via the static initializer.
+     *
+     * VM will invoke the initializeSystemClass method to complete
+     * the initialization for this class separated from clinit.
+     * Note that to use properties set by the VM, see the constraints
+     * described in the initializeSystemClass method.
+     */
     private static native void registerNatives();
     static {
         registerNatives();
@@ -1096,17 +1102,21 @@
      * Initialize the system class.  Called after thread initialization.
      */
     private static void initializeSystemClass() {
-        props = new Properties();
-        initProperties(props);
+        // There are certain system configurations that may be controlled by
+        // VM options such as the maximum amount of direct memory and
+        // Integer cache size used to support the object identity semantics
+        // of autoboxing.  Typically, the library will obtain these values
+        // from the properties set by the VM.  If the properties are for
+        // internal implementation use only, these properties should be
+        // removed from the system properties.
+        //
+        // See java.lang.Integer.IntegerCache and the
+        // sun.misc.VM.saveAndRemoveProperties method for example.
+        props = initSystemProperties();
+
         lineSeparator = props.getProperty("line.separator");
         sun.misc.Version.init();
 
-        // Gets and removes system properties that configure the Integer
-        // cache used to support the object identity semantics of autoboxing.
-        // At this time, the size of the cache may be controlled by the
-        // vm option -XX:AutoBoxCacheMax=<size>.
-        Integer.getAndRemoveCacheProperties();
-
         FileInputStream fdIn = new FileInputStream(FileDescriptor.in);
         FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
         FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
@@ -1127,17 +1137,6 @@
         // classes are used.
         sun.misc.VM.initializeOSEnvironment();
 
-        // Set the maximum amount of direct memory.  This value is controlled
-        // by the vm option -XX:MaxDirectMemorySize=<size>.  This method acts
-        // as an initializer only if it is called before sun.misc.VM.booted().
-        sun.misc.VM.maxDirectMemory();
-
-        // Set a boolean to determine whether ClassLoader.loadClass accepts
-        // array syntax.  This value is controlled by the system property
-        // "sun.lang.ClassLoader.allowArraySyntax".  This method acts as
-        // an initializer only if it is called before sun.misc.VM.booted().
-        sun.misc.VM.allowArraySyntax();
-
         // Subsystems that are invoked during initialization can invoke
         // sun.misc.VM.isBooted() in order to avoid doing things that should
         // wait until the application class loader has been set up.
@@ -1152,6 +1151,18 @@
         setJavaLangAccess();
     }
 
+    private static Properties initSystemProperties() {
+        Properties props = new Properties();
+        initProperties(props);  // initialized by the VM
+
+        // Save a private copy of the system properties object that
+        // can only be accessed by the internal implementation.  Remove
+        // certain system properties that are not intended for public access.
+        sun.misc.VM.saveAndRemoveProperties(props);
+
+        return props;
+    }
+
     private static void setJavaLangAccess() {
         // Allow privileged classes outside of java.lang
         sun.misc.SharedSecrets.setJavaLangAccess(new sun.misc.JavaLangAccess(){
--- a/src/share/classes/java/util/Properties.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/java/util/Properties.java	Mon Oct 11 20:22:27 2010 -0700
@@ -705,7 +705,7 @@
      *             <code>Strings</code>.
      */
     @Deprecated
-    public synchronized void save(OutputStream out, String comments)  {
+    public void save(OutputStream out, String comments)  {
         try {
             store(out, comments);
         } catch (IOException e) {
@@ -890,7 +890,7 @@
      * @see    #loadFromXML(InputStream)
      * @since 1.5
      */
-    public synchronized void storeToXML(OutputStream os, String comment)
+    public void storeToXML(OutputStream os, String comment)
         throws IOException
     {
         if (os == null)
@@ -929,8 +929,7 @@
      * @see    #loadFromXML(InputStream)
      * @since 1.5
      */
-    public synchronized void storeToXML(OutputStream os, String comment,
-                                       String encoding)
+    public void storeToXML(OutputStream os, String comment, String encoding)
         throws IOException
     {
         if (os == null)
--- a/src/share/classes/java/util/XMLUtils.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/java/util/XMLUtils.java	Mon Oct 11 20:22:27 2010 -0700
@@ -141,14 +141,13 @@
             comments.appendChild(doc.createTextNode(comment));
         }
 
-        Set keys = props.keySet();
-        Iterator i = keys.iterator();
-        while(i.hasNext()) {
-            String key = (String)i.next();
-            Element entry = (Element)properties.appendChild(
-                doc.createElement("entry"));
-            entry.setAttribute("key", key);
-            entry.appendChild(doc.createTextNode(props.getProperty(key)));
+        synchronized (props) {
+            for (String key : props.stringPropertyNames()) {
+                Element entry = (Element)properties.appendChild(
+                    doc.createElement("entry"));
+                entry.setAttribute("key", key);
+                entry.appendChild(doc.createTextNode(props.getProperty(key)));
+            }
         }
         emitDocument(doc, os, encoding);
     }
--- a/src/share/classes/java/util/zip/ZipFile.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/java/util/zip/ZipFile.java	Mon Oct 11 20:22:27 2010 -0700
@@ -85,8 +85,7 @@
     static {
         // A system prpperty to disable mmap use to avoid vm crash when
         // in-use zip file is accidently overwritten by others.
-        String prop = AccessController.doPrivileged(
-            new GetPropertyAction("sun.zip.disableMemoryMapping"));
+        String prop = sun.misc.VM.getSavedProperty("sun.zip.disableMemoryMapping");
         usemmap = (prop == null ||
                    !(prop.length() == 0 || prop.equalsIgnoreCase("true")));
     }
--- a/src/share/classes/sun/jkernel/DownloadManager.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/sun/jkernel/DownloadManager.java	Mon Oct 11 20:22:27 2010 -0700
@@ -25,13 +25,18 @@
 package sun.jkernel;
 
 import java.io.*;
+import java.net.URLStreamHandlerFactory;
+import java.net.URL;
+import java.net.MalformedURLException;
 import java.security.*;
 import java.util.*;
 import java.util.concurrent.*;
 import java.util.jar.*;
 import java.util.zip.*;
+import sun.misc.BootClassLoaderHook;
 import sun.misc.Launcher;
-import sun.misc.BootClassLoaderHook;
+import sun.misc.URLClassPath;
+import sun.net.www.ParseUtil;
 
 /**
  * Handles the downloading of additional JRE components.  The bootstrap class
@@ -658,31 +663,61 @@
         return getAppDataLocalLow() + getKernelJREDir();
     }
 
-    /**
-     * Returns an array of JAR files which have been added to the boot strap
-     * class path since the JVM was first booted.
-     */
-    public static synchronized File[] getAdditionalBootStrapPaths() {
-        return additionalBootStrapPaths != null ? additionalBootStrapPaths :
-                new File[0];
-    }
-
-
+    // To be revisited:
+    // How DownloadManager maintains its bootstrap class path.
+    // sun.misc.Launcher.getBootstrapClassPath() returns
+    // DownloadManager.getBootstrapClassPath() instead.
+    //
+    // So should no longer need to lock the Launcher.class.
+    // In addition, additionalBootStrapPaths is not really needed
+    // if it obtains the initial bootclasspath during DownloadManager's
+    // initialization.
     private static void addEntryToBootClassPath(File path) {
         // Must acquire these locks in this order
         synchronized(Launcher.class) {
-           synchronized(DownloadManager.class) {
+            synchronized(DownloadManager.class) {
                 File[] newBootStrapPaths = new File[
                     additionalBootStrapPaths.length + 1];
                 System.arraycopy(additionalBootStrapPaths, 0, newBootStrapPaths,
                         0, additionalBootStrapPaths.length);
                 newBootStrapPaths[newBootStrapPaths.length - 1] = path;
                 additionalBootStrapPaths = newBootStrapPaths;
-                Launcher.flushBootstrapClassPath();
+                if (bootstrapClassPath != null)
+                    bootstrapClassPath.addURL(getFileURL(path));
            }
        }
     }
 
+    /**
+     * Returns the kernel's bootstrap class path which includes the additional
+     * JARs downloaded
+     */
+    private static URLClassPath bootstrapClassPath = null;
+    private synchronized static
+           URLClassPath getBootClassPath(URLClassPath bcp,
+                                         URLStreamHandlerFactory factory)
+    {
+        if (bootstrapClassPath == null) {
+            bootstrapClassPath = new URLClassPath(bcp.getURLs(), factory);
+            for (File path : additionalBootStrapPaths) {
+                bootstrapClassPath.addURL(getFileURL(path));
+            }
+        }
+        return bootstrapClassPath;
+    }
+
+    private static URL getFileURL(File file) {
+        try {
+            file = file.getCanonicalFile();
+        } catch (IOException e) {}
+
+        try {
+            return ParseUtil.fileToEncodedURL(file);
+        } catch (MalformedURLException e) {
+            // Should never happen since we specify the protocol...
+            throw new InternalError();
+        }
+    }
 
     /**
      * Scan through java.ext.dirs to see if the lib/ext directory is included.
@@ -1680,8 +1715,10 @@
         }
     }
 
-    public File[] getAdditionalBootstrapPaths() {
-        return DownloadManager.getAdditionalBootStrapPaths();
+    public URLClassPath getBootstrapClassPath(URLClassPath bcp,
+                                              URLStreamHandlerFactory factory)
+    {
+        return DownloadManager.getBootClassPath(bcp, factory);
     }
 
     public boolean isCurrentThreadPrefetching() {
--- a/src/share/classes/sun/misc/BootClassLoaderHook.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/sun/misc/BootClassLoaderHook.java	Mon Oct 11 20:22:27 2010 -0700
@@ -27,6 +27,8 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.net.URLStreamHandlerFactory;
+import sun.misc.URLClassPath;
 
 /**
  * BootClassLoaderHook defines an interface for a hook to inject
@@ -94,20 +96,6 @@
         }
     }
 
-    private static final File[] EMPTY_FILE_ARRAY = new File[0];
-
-    /**
-     * Returns bootstrap class paths added by the hook.
-     */
-    public static File[] getBootstrapPaths() {
-        BootClassLoaderHook hook = getHook();
-        if (hook != null) {
-            return hook.getAdditionalBootstrapPaths();
-        } else {
-            return EMPTY_FILE_ARRAY;
-        }
-    }
-
     /**
      * Returns a pathname of a JAR or class that the hook loads
      * per this loadClass request; or null.
@@ -133,10 +121,13 @@
     public abstract boolean loadLibrary(String libname);
 
     /**
-     * Returns additional boot class paths added by the hook that
-     * should be searched by the boot class loader.
+     * Returns a bootstrap class path constructed by the hook.
+     *
+     * @param bcp VM's bootstrap class path
+     * @param factory Launcher's URL stream handler
      */
-    public abstract File[] getAdditionalBootstrapPaths();
+    public abstract URLClassPath getBootstrapClassPath(URLClassPath bcp,
+            URLStreamHandlerFactory factory);
 
     /**
      * Returns true if the current thread is in the process of doing
--- a/src/share/classes/sun/misc/Launcher.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/sun/misc/Launcher.java	Mon Oct 11 20:22:27 2010 -0700
@@ -47,7 +47,6 @@
 import java.security.Permission;
 import java.security.ProtectionDomain;
 import java.security.CodeSource;
-import sun.security.action.GetPropertyAction;
 import sun.security.util.SecurityConstants;
 import sun.net.www.ParseUtil;
 
@@ -57,6 +56,8 @@
 public class Launcher {
     private static URLStreamHandlerFactory factory = new Factory();
     private static Launcher launcher = new Launcher();
+    private static String bootClassPath =
+        System.getProperty("sun.boot.class.path");
 
     public static Launcher getLauncher() {
         return launcher;
@@ -227,7 +228,8 @@
                 File dir = new File(urls[i].getPath()).getParentFile();
                 if (dir != null && !dir.equals(prevDir)) {
                     // Look in architecture-specific subdirectory first
-                    String arch = System.getProperty("os.arch");
+                    // Read from the saved system properties to avoid deadlock
+                    String arch = VM.getSavedProperty("os.arch");
                     if (arch != null) {
                         File file = new File(new File(dir, arch), name);
                         if (file.exists()) {
@@ -377,19 +379,15 @@
         }
     }
 
-    private static URLClassPath bootstrapClassPath;
-
-    public static synchronized URLClassPath getBootstrapClassPath() {
-        if (bootstrapClassPath == null) {
-            String prop = AccessController.doPrivileged(
-                new GetPropertyAction("sun.boot.class.path"));
+    private static class BootClassPathHolder {
+        static final URLClassPath bcp;
+        static {
             URL[] urls;
-            if (prop != null) {
-                final String path = prop;
+            if (bootClassPath != null) {
                 urls = AccessController.doPrivileged(
                     new PrivilegedAction<URL[]>() {
                         public URL[] run() {
-                            File[] classPath = getClassPath(path);
+                            File[] classPath = getClassPath(bootClassPath);
                             int len = classPath.length;
                             Set<File> seenDirs = new HashSet<File>();
                             for (int i = 0; i < len; i++) {
@@ -410,25 +408,16 @@
             } else {
                 urls = new URL[0];
             }
-
-            bootstrapClassPath = new URLClassPath(urls, factory);
-            final File[] additionalBootStrapPaths =
-                BootClassLoaderHook.getBootstrapPaths();
-            AccessController.doPrivileged(new PrivilegedAction() {
-                public Object run() {
-                    for (int i=0; i<additionalBootStrapPaths.length; i++) {
-                        bootstrapClassPath.addURL(
-                            getFileURL(additionalBootStrapPaths[i]));
-                    }
-                    return null;
-                }
-            });
+            bcp = new URLClassPath(urls, factory);
         }
-        return bootstrapClassPath;
     }
 
-    public static synchronized void flushBootstrapClassPath() {
-        bootstrapClassPath = null;
+    public static URLClassPath getBootstrapClassPath() {
+        URLClassPath bcp = BootClassPathHolder.bcp;
+        // if DownloadManager is installed, return the bootstrap class path
+        // maintained by the Java kernel
+        BootClassLoaderHook hook = BootClassLoaderHook.getHook();
+        return hook == null ? bcp : hook.getBootstrapClassPath(bcp, factory);
     }
 
     private static URL[] pathToURLs(File[] path) {
--- a/src/share/classes/sun/misc/VM.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/src/share/classes/sun/misc/VM.java	Mon Oct 11 20:22:27 2010 -0700
@@ -170,33 +170,11 @@
     //
     private static long directMemory = 64 * 1024 * 1024;
 
-    // If this method is invoked during VM initialization, it initializes the
-    // maximum amount of allocatable direct buffer memory (in bytes) from the
-    // system property sun.nio.MaxDirectMemorySize.  The system property will
-    // be removed when it is accessed.
-    //
-    // If this method is invoked after the VM is booted, it returns the
-    // maximum amount of allocatable direct buffer memory.
+    // Returns the maximum amount of allocatable direct buffer memory.
+    // The directMemory variable is initialized during system initialization
+    // in the saveAndRemoveProperties method.
     //
     public static long maxDirectMemory() {
-        if (booted)
-            return directMemory;
-
-        Properties p = System.getProperties();
-        String s = (String)p.remove("sun.nio.MaxDirectMemorySize");
-        System.setProperties(p);
-
-        if (s != null) {
-            if (s.equals("-1")) {
-                // -XX:MaxDirectMemorySize not given, take default
-                directMemory = Runtime.getRuntime().maxMemory();
-            } else {
-                long l = Long.parseLong(s);
-                if (l > -1)
-                    directMemory = l;
-            }
-        }
-
         return directMemory;
     }
 
@@ -212,26 +190,82 @@
     private static boolean defaultAllowArraySyntax = false;
     private static boolean allowArraySyntax = defaultAllowArraySyntax;
 
-    // If this method is invoked during VM initialization, it initializes the
-    // allowArraySyntax boolean based on the value of the system property
+    // The allowArraySyntax boolean is initialized during system initialization
+    // in the saveAndRemoveProperties method.
+    //
+    // It is initialized based on the value of the system property
     // "sun.lang.ClassLoader.allowArraySyntax".  If the system property is not
     // provided, the default for 1.5 is "true".  In 1.6, the default will be
     // "false".  If the system property is provided, then the value of
     // allowArraySyntax will be equal to "true" if Boolean.parseBoolean()
     // returns "true".   Otherwise, the field will be set to "false".
     //
-    // If this method is invoked after the VM is booted, it returns the
-    // allowArraySyntax boolean set during initialization.
+    public static boolean allowArraySyntax() {
+        return allowArraySyntax;
+    }
+
+    /**
+     * Returns the system property of the specified key saved at
+     * system initialization time.  This method should only be used
+     * for the system properties that are not changed during runtime.
+     * It accesses a private copy of the system properties so
+     * that user's locking of the system properties object will not
+     * cause the library to deadlock.
+     *
+     * Note that the saved system properties do not include
+     * the ones set by sun.misc.Version.init().
+     *
+     */
+    public static String getSavedProperty(String key) {
+        if (savedProps.isEmpty())
+            throw new IllegalStateException("Should be non-empty if initialized");
+
+        return savedProps.getProperty(key);
+    }
+
+    private static final Properties savedProps = new Properties();
+
+    // Save a private copy of the system properties and remove
+    // the system properties that are not intended for public access.
     //
-    public static boolean allowArraySyntax() {
-        if (!booted) {
-            String s
-                = System.getProperty("sun.lang.ClassLoader.allowArraySyntax");
-            allowArraySyntax = (s == null
-                                ? defaultAllowArraySyntax
-                                : Boolean.parseBoolean(s));
+    // This method can only be invoked during system initialization.
+    public static void saveAndRemoveProperties(Properties props) {
+        if (booted)
+            throw new IllegalStateException("System initialization has completed");
+
+        savedProps.putAll(props);
+
+        // Set the maximum amount of direct memory.  This value is controlled
+        // by the vm option -XX:MaxDirectMemorySize=<size>.
+        // The maximum amount of allocatable direct buffer memory (in bytes)
+        // from the system property sun.nio.MaxDirectMemorySize set by the VM.
+        // The system property will be removed.
+        String s = (String)props.remove("sun.nio.MaxDirectMemorySize");
+        if (s != null) {
+            if (s.equals("-1")) {
+                // -XX:MaxDirectMemorySize not given, take default
+                directMemory = Runtime.getRuntime().maxMemory();
+            } else {
+                long l = Long.parseLong(s);
+                if (l > -1)
+                    directMemory = l;
+            }
         }
-        return allowArraySyntax;
+
+        // Set a boolean to determine whether ClassLoader.loadClass accepts
+        // array syntax.  This value is controlled by the system property
+        // "sun.lang.ClassLoader.allowArraySyntax".
+        s = props.getProperty("sun.lang.ClassLoader.allowArraySyntax");
+        allowArraySyntax = (s == null
+                               ? defaultAllowArraySyntax
+                               : Boolean.parseBoolean(s));
+
+        // Remove other private system properties
+        // used by java.lang.Integer.IntegerCache
+        props.remove("java.lang.Integer.IntegerCache.high");
+
+        // used by java.util.zip.ZipFile
+        props.remove("sun.zip.disableMemoryMapping");
     }
 
     // Initialize any miscellenous operating system settings that need to be
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/lang/ClassLoader/deadlock/GetResource.java	Mon Oct 11 20:22:27 2010 -0700
@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.util.Properties;
+import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.BrokenBarrierException;
+import java.io.IOException;
+import java.net.URL;
+
+/* @test
+ * @bug 6977738
+ * @summary Test ClassLoader.getResource() that should not deadlock
+ #          if another thread is holding the system properties object
+ *
+ * @build GetResource
+ * @run main GetResource
+ */
+
+public class GetResource {
+    CyclicBarrier go = new CyclicBarrier(2);
+    CyclicBarrier done = new CyclicBarrier(2);
+    Thread t1, t2;
+    public GetResource() {
+        t1 = new Thread() {
+            public void run() {
+                Properties prop = System.getProperties();
+                synchronized (prop) {
+                    System.out.println("Thread 1 ready");
+                    try {
+                        go.await();
+                        prop.put("property", "value");
+                        prop.store(System.out, "");
+                        done.await();   // keep holding the lock until t2 finishes
+                    } catch (InterruptedException e) {
+                        throw new RuntimeException(e);
+                    } catch (BrokenBarrierException e) {
+                        throw new RuntimeException(e);
+                    } catch (IOException e) {
+                        throw new RuntimeException(e);
+                    }
+                }
+                System.out.println("Thread 1 exits");
+            }
+        };
+
+        t2 = new Thread()  {
+            public void run() {
+                System.out.println("Thread 2 ready");
+                try {
+                    go.await();  // wait until t1 holds the lock of the system properties
+
+                    URL u1 = Thread.currentThread().getContextClassLoader().getResource("unknownresource");
+                    URL u2 = Thread.currentThread().getContextClassLoader().getResource("sun/util/resources/CalendarData.class");
+                    if (u2 == null) {
+                        throw new RuntimeException("Test failed: resource not found");
+                    }
+                    done.await();
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                } catch (BrokenBarrierException e) {
+                    throw new RuntimeException(e);
+                }
+                System.out.println("Thread 2 exits");
+            }
+        };
+    }
+
+    public void run() throws Exception {
+        t1.start();
+        t2.start();
+        try {
+            t1.join();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+            throw e;
+        }
+        try {
+            t2.join();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+            throw e;
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        new GetResource().run();
+    }
+}
--- a/test/sun/misc/BootClassLoaderHook/TestHook.java	Mon Oct 11 10:55:04 2010 +0100
+++ b/test/sun/misc/BootClassLoaderHook/TestHook.java	Mon Oct 11 20:22:27 2010 -0700
@@ -24,7 +24,10 @@
 import java.io.File;
 import java.util.TreeSet;
 import java.util.Set;
+import java.net.URLStreamHandlerFactory;
 import sun.misc.BootClassLoaderHook;
+import sun.misc.URLClassPath;
+
 
 /* @test
  * @bug     6888802
@@ -68,10 +71,6 @@
         for (String s : copy) {
             System.out.println("  Loaded " + s);
         }
-
-        if (BootClassLoaderHook.getBootstrapPaths().length > 0) {
-           throw new RuntimeException("Unexpected returned value from getBootstrapPaths()");
-        }
     }
 
     private static void testHook() throws Exception {
@@ -98,8 +97,9 @@
         return false;
     }
 
-    public File[] getAdditionalBootstrapPaths() {
-        return new File[0];
+    public URLClassPath getBootstrapClassPath(URLClassPath bcp,
+            URLStreamHandlerFactory factory) {
+        return bcp;
     }
 
     public boolean isCurrentThreadPrefetching() {