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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* version 2 for more details (a copy is included in the LICENSE file that
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* 2 along with this work; if not, write to the Free Software Foundation,
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/*
* @test
* @bug 6303187
* @summary Test that no locks are held when a monitor attribute is sampled
* or notif delivered.
* @author Eamonn McManus
* @key intermittent
* @modules java.management
* @run clean StringMonitorDeadlockTest
* @run build StringMonitorDeadlockTest
* @run main StringMonitorDeadlockTest 1
* @run main StringMonitorDeadlockTest 2
* @run main StringMonitorDeadlockTest 3
* @run main StringMonitorDeadlockTest 4
*/
import java.lang.management.ManagementFactory;
import java.util.concurrent.atomic.AtomicInteger;
import javax.management.JMX;
import javax.management.MBeanServer;
import javax.management.Notification;
import javax.management.NotificationListener;
import javax.management.ObjectName;
import javax.management.monitor.StringMonitor;
import javax.management.monitor.StringMonitorMBean;
public class StringMonitorDeadlockTest {
public static void main(String[] args) throws Exception {
if (args.length != 1)
throw new Exception("Arg should be test number");
int testNo = Integer.parseInt(args[0]) - 1;
TestCase test = testCases[testNo];
System.out.println("Test: " + test.getDescription());
test.run();
System.out.println("Test passed");
}
private static enum When {IN_GET_ATTRIBUTE, IN_NOTIFY};
private static abstract class TestCase {
TestCase(String description, When when) {
this.description = description;
this.when = when;
}
void run() throws Exception {
final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
final ObjectName observedName = new ObjectName("a:b=c");
final ObjectName monitorName = new ObjectName("a:type=Monitor");
mbs.registerMBean(new StringMonitor(), monitorName);
final StringMonitorMBean monitorProxy =
JMX.newMBeanProxy(mbs, monitorName, StringMonitorMBean.class);
final TestMBean observedProxy =
JMX.newMBeanProxy(mbs, observedName, TestMBean.class);
final Runnable sensitiveThing = new Runnable() {
public void run() {
doSensitiveThing(monitorProxy, observedName);
}
};
final Runnable nothing = new Runnable() {
public void run() {}
};
final Runnable withinGetAttribute =
(when == When.IN_GET_ATTRIBUTE) ? sensitiveThing : nothing;
mbs.registerMBean(new Test(withinGetAttribute), observedName);
monitorProxy.addObservedObject(observedName);
monitorProxy.setObservedAttribute("Thing");
monitorProxy.setStringToCompare("old");
monitorProxy.setGranularityPeriod(10L); // 10 ms
monitorProxy.setNotifyDiffer(true);
final int initGetCount = observedProxy.getGetCount();
monitorProxy.start();
int getCount = initGetCount;
for (int i = 0; i < 500; i++) { // 500 * 10 = 5 seconds
getCount = observedProxy.getGetCount();
if (getCount != initGetCount)
break;
Thread.sleep(10);
}
if (getCount <= initGetCount)
throw new Exception("Test failed: presumable deadlock");
// This won't show up as a deadlock in CTRL-\ or in
// ThreadMXBean.findDeadlockedThreads(), because they don't
// see that thread A is waiting for thread B (B.join()), and
// thread B is waiting for a lock held by thread A
// Now we know the monitor has observed the initial value,
// so if we want to test notify behaviour we can trigger by
// exceeding the threshold.
if (when == When.IN_NOTIFY) {
final AtomicInteger notifCount = new AtomicInteger();
final NotificationListener listener = new NotificationListener() {
public void handleNotification(Notification n, Object h) {
Thread t = new Thread(sensitiveThing);
t.start();
try {
t.join();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
notifCount.incrementAndGet();
}
};
mbs.addNotificationListener(monitorName, listener, null, null);
observedProxy.setThing("new");
for (int i = 0; i < 500 && notifCount.get() == 0; i++)
Thread.sleep(10);
if (notifCount.get() == 0)
throw new Exception("Test failed: presumable deadlock");
}
}
abstract void doSensitiveThing(StringMonitorMBean monitorProxy,
ObjectName observedName);
String getDescription() {
return description;
}
private final String description;
private final When when;
}
private static final TestCase[] testCases = {
new TestCase("Remove monitored MBean within monitored getAttribute",
When.IN_GET_ATTRIBUTE) {
@Override
void doSensitiveThing(StringMonitorMBean monitorProxy,
ObjectName observedName) {
monitorProxy.removeObservedObject(observedName);
}
},
new TestCase("Stop monitor within monitored getAttribute",
When.IN_GET_ATTRIBUTE) {
@Override
void doSensitiveThing(StringMonitorMBean monitorProxy,
ObjectName observedName) {
monitorProxy.stop();
}
},
new TestCase("Remove monitored MBean within threshold listener",
When.IN_NOTIFY) {
@Override
void doSensitiveThing(StringMonitorMBean monitorProxy,
ObjectName observedName) {
monitorProxy.removeObservedObject(observedName);
}
},
new TestCase("Stop monitor within threshold listener",
When.IN_NOTIFY) {
@Override
void doSensitiveThing(StringMonitorMBean monitorProxy,
ObjectName observedName) {
monitorProxy.stop();
}
},
};
public static interface TestMBean {
public String getThing();
public void setThing(String thing);
public int getGetCount();
}
public static class Test implements TestMBean {
public Test(Runnable runWithinGetAttribute) {
this.runWithinGetAttribute = runWithinGetAttribute;
}
public String getThing() {
Thread t = new Thread(runWithinGetAttribute);
t.start();
try {
t.join();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
getCount++;
return thing;
}
public void setThing(String thing) {
this.thing = thing;
}
public int getGetCount() {
return getCount;
}
private final Runnable runWithinGetAttribute;
private volatile int getCount;
private volatile String thing;
}
}