8260366: ExtendedSocketOptions <clinit> can deadlock in some circumstances
Reviewed-by: dfuchs
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de3f519dc9
commit
240f2a1bb7
src/java.base/share/classes/sun/net/ext
test/jdk/sun/net/ext
@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved.
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* Copyright (c) 2016, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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@ -167,25 +167,35 @@ public abstract class ExtendedSocketOptions {
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private static volatile ExtendedSocketOptions instance;
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public static final ExtendedSocketOptions getInstance() { return instance; }
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/** Registers support for extended socket options. Invoked by the jdk.net module. */
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public static final void register(ExtendedSocketOptions extOptions) {
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if (instance != null)
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throw new InternalError("Attempting to reregister extended options");
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instance = extOptions;
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}
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static {
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public static ExtendedSocketOptions getInstance() {
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ExtendedSocketOptions ext = instance;
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if (ext != null) {
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return ext;
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}
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try {
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// If the class is present, it will be initialized which
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// triggers registration of the extended socket options.
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Class<?> c = Class.forName("jdk.net.ExtendedSocketOptions");
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ext = instance;
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} catch (ClassNotFoundException e) {
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// the jdk.net module is not present => no extended socket options
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instance = new NoExtendedSocketOptions();
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synchronized (ExtendedSocketOptions.class) {
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ext = instance;
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if (ext != null) {
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return ext;
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}
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// the jdk.net module is not present => no extended socket options
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ext = instance = new NoExtendedSocketOptions();
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}
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}
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return ext;
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}
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/** Registers support for extended socket options. Invoked by the jdk.net module. */
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public static synchronized void register(ExtendedSocketOptions extOptions) {
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if (instance != null)
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throw new InternalError("Attempting to reregister extended options");
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instance = extOptions;
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}
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static final class NoExtendedSocketOptions extends ExtendedSocketOptions {
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158
test/jdk/sun/net/ext/ExtendedSocketOptionsTest.java
Normal file
158
test/jdk/sun/net/ext/ExtendedSocketOptionsTest.java
Normal file
@ -0,0 +1,158 @@
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/*
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* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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import org.testng.Assert;
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import org.testng.annotations.Test;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import java.util.concurrent.Callable;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import java.util.concurrent.Future;
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/**
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* @test
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* @bug 8260366
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* @summary Verify that concurrent classloading of sun.net.ext.ExtendedSocketOptions and
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* jdk.net.ExtendedSocketOptions doesn't lead to a deadlock
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* @modules java.base/sun.net.ext:open
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* jdk.net
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* @run testng/othervm ExtendedSocketOptionsTest
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* @run testng/othervm ExtendedSocketOptionsTest
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* @run testng/othervm ExtendedSocketOptionsTest
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* @run testng/othervm ExtendedSocketOptionsTest
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* @run testng/othervm ExtendedSocketOptionsTest
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*/
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public class ExtendedSocketOptionsTest {
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/**
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* Loads {@code jdk.net.ExtendedSocketOptions} and {@code sun.net.ext.ExtendedSocketOptions}
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* and invokes {@code sun.net.ext.ExtendedSocketOptions#getInstance()} concurrently in a thread
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* of their own and expects the classloading of both those classes
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* to succeed. Additionally, after these tasks are done, calls the
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* sun.net.ext.ExtendedSocketOptions#getInstance() and expects it to return a registered
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* ExtendedSocketOptions instance.
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*/
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@Test
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public void testConcurrentClassLoad() throws Exception {
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final CountDownLatch taskTriggerLatch = new CountDownLatch(4);
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final List<Callable<?>> tasks = new ArrayList<>();
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tasks.add(new Task("jdk.net.ExtendedSocketOptions", taskTriggerLatch));
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tasks.add(new Task("sun.net.ext.ExtendedSocketOptions", taskTriggerLatch));
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// add a couple of tasks which call sun.net.ext.ExtendedSocketOptions#getInstance
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tasks.add(new GetInstanceTask(taskTriggerLatch));
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tasks.add(new GetInstanceTask(taskTriggerLatch));
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final ExecutorService executor = Executors.newFixedThreadPool(tasks.size());
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try {
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final Future<?>[] results = new Future[tasks.size()];
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// submit
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int i = 0;
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for (final Callable<?> task : tasks) {
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results[i++] = executor.submit(task);
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}
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// wait for completion
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for (i = 0; i < tasks.size(); i++) {
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results[i].get();
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}
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} finally {
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executor.shutdownNow();
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}
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// check that the sun.net.ext.ExtendedSocketOptions#getInstance() does indeed return
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// the registered instance
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final Object extSocketOptions = callSunNetExtSocketOptionsGetInstance();
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Assert.assertNotNull(extSocketOptions, "sun.net.ext.ExtendedSocketOptions#getInstance()" +
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" unexpectedly returned null");
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// now verify that each call to getInstance(), either in the tasks or here, returned the exact
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// same instance of ExtendedSocketOptions
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Assert.assertEquals(2, GetInstanceTask.extendedSocketOptionsInstances.size());
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for (final Object inst : GetInstanceTask.extendedSocketOptionsInstances) {
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Assert.assertSame(inst, extSocketOptions, "sun.net.ext.ExtendedSocketOptions#getInstance()" +
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" returned different instances");
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}
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}
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/**
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* Reflectively calls sun.net.ext.ExtendedSocketOptions#getInstance() and returns
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* the result
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*/
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private static Object callSunNetExtSocketOptionsGetInstance() throws Exception {
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final Class<?> k = Class.forName("sun.net.ext.ExtendedSocketOptions");
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return k.getDeclaredMethod("getInstance").invoke(null);
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}
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private static class Task implements Callable<Class<?>> {
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private final String className;
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private final CountDownLatch latch;
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private Task(final String className, final CountDownLatch latch) {
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this.className = className;
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this.latch = latch;
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}
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@Override
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public Class<?> call() {
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System.out.println(Thread.currentThread().getName() + " loading " + this.className);
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try {
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// let the other tasks know we are ready to trigger our work
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latch.countDown();
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// wait for the other task to let us know they are ready to trigger their work too
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latch.await();
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return Class.forName(this.className);
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} catch (Exception e) {
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throw new RuntimeException(e);
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}
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}
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}
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private static class GetInstanceTask implements Callable<Object> {
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// keeps track of the instances returned by calls to sun.nex.ext.ExtendedSocketOptions#getInstance()
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// by the GetInstanceTask(s)
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private static final List<Object> extendedSocketOptionsInstances = Collections.synchronizedList(new ArrayList<>());
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private final CountDownLatch latch;
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private GetInstanceTask(final CountDownLatch latch) {
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this.latch = latch;
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}
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@Override
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public Object call() {
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System.out.println(Thread.currentThread().getName()
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+ " calling sun.net.ext.ExtendedSocketOptions#getInstance()");
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try {
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// let the other tasks know we are ready to trigger our work
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latch.countDown();
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// wait for the other task to let us know they are ready to trigger their work too
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latch.await();
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// let's call getInstance on sun.net.ext.ExtendedSocketOptions
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final Object inst = callSunNetExtSocketOptionsGetInstance();
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extendedSocketOptionsInstances.add(inst);
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return inst;
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} catch (Exception e) {
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throw new RuntimeException(e);
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}
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}
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}
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}
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