Mega Code Archive
Guarantee that threads are woken in the same order in which they waited
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import java.util.Vector;
public class Wake {
private Vector<Object> stopped = new Vector<Object>();
public void stopOne() {
Object myLock = new Object();
synchronized (myLock) {
stopped.addElement(myLock);
try {
myLock.wait();
} catch (InterruptedException e) {
}
}
}
public void wakeOne() {
Object theLock = null;
synchronized (stopped) {
if (stopped.size() != 0) {
theLock = stopped.firstElement();
stopped.removeElementAt(0);
}
}
if (theLock != null) {
synchronized (theLock) {
theLock.notify();
}
}
}
public static void main(String args[]) {
Wake queue = new Wake();
Runnable r = new RunThis(queue);
Thread t;
for (int i = 0; i < 10; i++) {
t = new Thread(r);
t.start();
}
for (int i = 0; i < 11; i++) {
try {
Thread.sleep((long) (Math.random() * 1000));
} catch (InterruptedException e) {
}
System.out.println("About to wake one thread");
queue.wakeOne();
}
}
}
class RunThis implements Runnable {
Wake w;
public RunThis(Wake w) {
this.w = w;
}
public void run() {
System.out.println("Thread starting, name is " + Thread.currentThread().getName());
w.stopOne();
System.out.println("Thread woken up, name is " + Thread.currentThread().getName());
}
}
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