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/*
* @test
* @bug 5086470
* @summary Basic Test for the following methods:
* - ThreadMXBean.findDeadlockedThreads()
* - ThreadMXBean.findMonitorDeadlockedThreads()
* @author Mandy Chung
*
* @build MonitorDeadlock
* @build SynchronizerDeadlock
* @build ThreadDump
* @run main/othervm FindDeadlocks
*/
import java.lang.management.*;
import java.util.*;
public class FindDeadlocks {
static ThreadMXBean mbean = ManagementFactory.getThreadMXBean();
public static void main(String[] argv) {
ThreadMXBean mbean = ManagementFactory.getThreadMXBean();
// create deadlocked threads
MonitorDeadlock md = new MonitorDeadlock();
// no deadlock
if (findDeadlocks() != null) {
throw new RuntimeException("TEST FAILED: Should return null.");
}
// Let the threads to proceed
md.goDeadlock();
// wait until the deadlock is ready
md.waitUntilDeadlock();
long[] mthreads = findDeadlocks();
if (mthreads == null) {
ThreadDump.dumpStacks();
throw new RuntimeException("TEST FAILED: Deadlock not detected.");
}
md.checkResult(mthreads);
// create deadlocked threads on synchronizers
SynchronizerDeadlock sd = new SynchronizerDeadlock();
// Let the threads to proceed
sd.goDeadlock();
// wait until the deadlock is ready
sd.waitUntilDeadlock();
// Find Deadlock
long[] threads = findDeadlocks();
if (threads == null) {
ThreadDump.dumpStacks();
throw new RuntimeException("TEST FAILED: Deadlock not detected.");
}
// form a list of newly deadlocked threads
long[] newList = new long[threads.length - mthreads.length];
int count = 0;
for (int i = 0; i < threads.length; i++) {
long id = threads[i];
boolean isNew = true;
for (int j = 0; j < mthreads.length; j++) {
if (mthreads[j] == id) {
isNew = false;
break;
}
}
if (isNew) {
newList[count++] = id;
}
}
if (mbean.isSynchronizerUsageSupported()) {
sd.checkResult(newList);
} else {
// monitoring of synchronizer usage not supported
if (count != 0) {
throw new RuntimeException("TEST FAILED: NewList should be empty.");
}
}
// Print Deadlock stack trace
System.out.println("Found threads that are in deadlock:-");
ThreadInfo[] infos = mbean.getThreadInfo(threads, Integer.MAX_VALUE);
for (int i = 0; i < infos.length; i++) {
ThreadDump.printThreadInfo(infos[i]);
}
System.out.println("Test passed");
}
static long[] findDeadlocks() {
long[] threads;
if (mbean.isSynchronizerUsageSupported()) {
threads = mbean.findDeadlockedThreads();
} else {
threads = mbean.findMonitorDeadlockedThreads();
}
return threads;
}
}