test/java/lang/Thread/ThreadStateTest.java
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@@ -1,7 +1,7 @@
/*
- * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2011, 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.
@@ -32,25 +32,20 @@
* @build ThreadStateTest
* @run main ThreadStateTest
*/
import java.util.concurrent.locks.LockSupport;
-import java.util.concurrent.Semaphore;
+import java.util.concurrent.Phaser;
public class ThreadStateTest {
+ // maximum number of retries when checking for thread state.
+ static final int MAX_RETRY = 500;
+
private static boolean testFailed = false;
- static class Lock {
- private String name;
- Lock(String name) {
- this.name = name;
- }
- public String toString() {
- return name;
- }
- }
- private static Lock globalLock = new Lock("my lock");
+ // used to achieve waiting states
+ static final Object globalLock = new Object();
public static void main(String[] argv) {
// Call Thread.getState to force all initialization done
// before test verification begins.
Thread.currentThread().getState();
@@ -91,26 +86,40 @@
myThread.goSleeping();
checkThreadState(myThread, Thread.State.TIMED_WAITING);
myThread.terminate();
- checkThreadState(myThread, Thread.State.TERMINATED);
-
try {
myThread.join();
} catch (InterruptedException e) {
e.printStackTrace();
System.out.println("Unexpected exception.");
testFailed = true;
}
+ checkThreadState(myThread, Thread.State.TERMINATED);
+
+
if (testFailed)
throw new RuntimeException("TEST FAILED.");
System.out.println("Test passed.");
}
private static void checkThreadState(Thread t, Thread.State expected) {
- Thread.State state = t.getState();
+ // wait for the thread to transition to the expected state.
+ // There is a small window between the thread checking the state
+ // and the thread actual entering that state.
+ Thread.State state;
+ int retryCount=0;
+ while ((state = t.getState()) != expected && retryCount < MAX_RETRY) {
+ if (state != Thread.State.RUNNABLE) {
+ throw new RuntimeException("Thread not in expected state yet," +
+ " but it should at least be RUNNABLE");
+ }
+ goSleep(10);
+ retryCount++;
+ }
+
System.out.println("Checking thread state " + state);
if (state == null) {
throw new RuntimeException(t.getName() + " expected to have " +
expected + " but got null.");
}
@@ -119,17 +128,10 @@
throw new RuntimeException(t.getName() + " expected to have " +
expected + " but got " + state);
}
}
- private static String getLockName(Object lock) {
- if (lock == null) return null;
-
- return lock.getClass().getName() + '@' +
- Integer.toHexString(System.identityHashCode(lock));
- }
-
private static void goSleep(long ms) {
try {
Thread.sleep(ms);
} catch (InterruptedException e) {
e.printStackTrace();
@@ -137,11 +139,13 @@
testFailed = true;
}
}
static class MyThread extends Thread {
- private ThreadExecutionSynchronizer thrsync = new ThreadExecutionSynchronizer();
+ // Phaser to sync between the main thread putting
+ // this thread into various states
+ private Phaser phaser = new Phaser(2);
MyThread(String name) {
super(name);
}
@@ -151,16 +155,18 @@
private final int TIMED_WAITING = 3;
private final int PARKED = 4;
private final int TIMED_PARKED = 5;
private final int SLEEPING = 6;
private final int TERMINATE = 7;
- private int state = RUNNABLE;
+ private volatile int state = RUNNABLE;
+
private boolean done = false;
public void run() {
// Signal main thread to continue.
- thrsync.signal();
+ phaser.arriveAndAwaitAdvance();
+
while (!done) {
switch (state) {
case RUNNABLE: {
double sum = 0;
for (int i = 0; i < 1000; i++) {
@@ -170,11 +176,11 @@
}
break;
}
case BLOCKED: {
// signal main thread.
- thrsync.signal();
+ phaser.arrive();
System.out.println(" myThread is going to block.");
synchronized (globalLock) {
// finish blocking
state = RUNNABLE;
}
@@ -181,11 +187,11 @@
break;
}
case WAITING: {
synchronized (globalLock) {
// signal main thread.
- thrsync.signal();
+ phaser.arrive();
System.out.println(" myThread is going to wait.");
try {
globalLock.wait();
} catch (InterruptedException e) {
// ignore
@@ -194,11 +200,11 @@
break;
}
case TIMED_WAITING: {
synchronized (globalLock) {
// signal main thread.
- thrsync.signal();
+ phaser.arrive();
System.out.println(" myThread is going to timed wait.");
try {
globalLock.wait(10000);
} catch (InterruptedException e) {
// ignore
@@ -206,20 +212,20 @@
}
break;
}
case PARKED: {
// signal main thread.
- thrsync.signal();
+ phaser.arrive();
System.out.println(" myThread is going to park.");
LockSupport.park();
// give a chance for the main thread to block
goSleep(10);
break;
}
case TIMED_PARKED: {
// signal main thread.
- thrsync.signal();
+ phaser.arrive();
System.out.println(" myThread is going to timed park.");
long deadline = System.currentTimeMillis() + 10000*1000;
LockSupport.parkUntil(deadline);
// give a chance for the main thread to block
@@ -226,11 +232,11 @@
goSleep(10);
break;
}
case SLEEPING: {
// signal main thread.
- thrsync.signal();
+ phaser.arrive();
System.out.println(" myThread is going to sleep.");
try {
Thread.sleep(1000000);
} catch (InterruptedException e) {
// finish sleeping
@@ -238,75 +244,68 @@
}
break;
}
case TERMINATE: {
done = true;
- // signal main thread.
- thrsync.signal();
break;
}
default:
break;
}
}
}
+
public void waitUntilStarted() {
// wait for MyThread.
- thrsync.waitForSignal();
- goSleep(10);
+ phaser.arriveAndAwaitAdvance();
}
public void goBlocked() {
System.out.println("Waiting myThread to go blocked.");
setState(BLOCKED);
- // wait for MyThread to get blocked
- thrsync.waitForSignal();
- goSleep(20);
+ // wait for MyThread to get to a point just before being blocked
+ phaser.arriveAndAwaitAdvance();
}
public void goWaiting() {
System.out.println("Waiting myThread to go waiting.");
setState(WAITING);
- // wait for MyThread to wait on object.
- thrsync.waitForSignal();
- goSleep(20);
+ // wait for MyThread to get to just before wait on object.
+ phaser.arriveAndAwaitAdvance();
}
+
public void goTimedWaiting() {
System.out.println("Waiting myThread to go timed waiting.");
setState(TIMED_WAITING);
- // wait for MyThread timed wait call.
- thrsync.waitForSignal();
- goSleep(20);
+ // wait for MyThread to get to just before timed wait call.
+ phaser.arriveAndAwaitAdvance();
}
+
public void goParked() {
System.out.println("Waiting myThread to go parked.");
setState(PARKED);
- // wait for MyThread state change to PARKED.
- thrsync.waitForSignal();
- goSleep(20);
+ // wait for MyThread to get to just before parked.
+ phaser.arriveAndAwaitAdvance();
}
+
public void goTimedParked() {
System.out.println("Waiting myThread to go timed parked.");
setState(TIMED_PARKED);
- // wait for MyThread.
- thrsync.waitForSignal();
- goSleep(20);
+ // wait for MyThread to get to just before timed park.
+ phaser.arriveAndAwaitAdvance();
}
public void goSleeping() {
System.out.println("Waiting myThread to go sleeping.");
setState(SLEEPING);
- // wait for MyThread.
- thrsync.waitForSignal();
- goSleep(20);
+ // wait for MyThread to get to just before sleeping
+ phaser.arriveAndAwaitAdvance();
}
+
public void terminate() {
System.out.println("Waiting myThread to terminate.");
setState(TERMINATE);
- // wait for MyThread.
- thrsync.waitForSignal();
- goSleep(20);
}
private void setState(int newState) {
switch (state) {
case BLOCKED:
@@ -335,52 +334,6 @@
state = newState;
break;
}
}
}
-
-
-
- static class ThreadExecutionSynchronizer {
-
- private boolean waiting;
- private Semaphore semaphore;
-
- public ThreadExecutionSynchronizer() {
- semaphore = new Semaphore(1);
- waiting = false;
- }
-
- // Synchronizes two threads execution points.
- // Basically any thread could get scheduled to run and
- // it is not possible to know which thread reaches expected
- // execution point. So whichever thread reaches a execution
- // point first wait for the second thread. When the second thread
- // reaches the expected execution point will wake up
- // the thread which is waiting here.
- void stopOrGo() {
- semaphore.acquireUninterruptibly(); // Thread can get blocked.
- if (!waiting) {
- waiting = true;
- // Wait for second thread to enter this method.
- while(!semaphore.hasQueuedThreads()) {
- try {
- Thread.sleep(20);
- } catch (InterruptedException xx) {}
- }
- semaphore.release();
- } else {
- waiting = false;
- semaphore.release();
- }
- }
-
- // Wrapper function just for code readability.
- void waitForSignal() {
- stopOrGo();
- }
-
- void signal() {
- stopOrGo();
- }
- }
}