7188755: Crash due to missing synchronization on gconf_client in DefaultProxySelector.c

Reviewed-by: chegar
Contributed-by: NChristian Schulte <cs@schulte.it>

src/share/classes/sun/net/spi/DefaultProxySelector.java

@@ -351,5 +351,5 @@ public class DefaultProxySelector extends ProxySelector {
     }
 
     private native static boolean init();
-    private native Proxy getSystemProxy(String protocol, String host);
+    private synchronized native Proxy getSystemProxy(String protocol, String host);
 }

test/java/net/ProxySelector/MultiThreadedSystemProxies.java

+/*
+ * Copyright (c) 2012 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.
+ */
+/*
+ * @test
+ * @bug 7188755
+ * @run main/othervm MultiThreadedSystemProxies
+ * @summary Crash due to missing synchronization on gconf_client in
+ *          DefaultProxySelector.c
+ */
+import java.net.ProxySelector;
+import java.net.URI;
+
+/* Racey test, not guaranteed to fail, but if it does we have a problem. */
+
+public class MultiThreadedSystemProxies {
+    static final int NUM_THREADS = 100;
+
+    public static void main(String[] args) throws Exception {
+        System.setProperty("java.net.useSystemProxies", "true");
+        final ProxySelector ps = ProxySelector.getDefault();
+        final URI uri = new URI("http://ubuntu.com");
+        Thread[] threads = new Thread[NUM_THREADS];
+
+        for (int i = 0; i < NUM_THREADS; i++) {
+            threads[i] = new Thread(new Runnable() {
+                @Override
+                public void run() {
+                    try {
+                        ps.select(uri);
+                    } catch (Exception x) {
+                        throw new RuntimeException(x);
+                    }
+                }
+            });
+        }
+        for (int i = 0; i < NUM_THREADS; i++) {
+            threads[i].start();
+        }
+        for (int i = 0; i < NUM_THREADS; i++) {
+            threads[i].join();
+        }
+    }
+}