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Locks On Locks On Locks
package sandbox;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
import org.apache.commons.lang3.time.StopWatch;
public class LockOnLocksOnLocks {
/**
* @param args
* @throws InterruptedException
*/
public static void main(String[] args) throws InterruptedException {
System.err.print("-> ");
int simultaneous = 2028;
CountDownLatch readySignal = new CountDownLatch(simultaneous);
CountDownLatch startSignal = new CountDownLatch(1);
CountDownLatch doneSignal = new CountDownLatch(simultaneous);
StopWatch stopWatch = new StopWatch();
int count = 1000000;
for(int i = 0; i < simultaneous; i++) {
try {
// -> 0:04:34.254 (274s)
// new Thread(new GlobalLockWorker(readySignal, startSignal, doneSignal, i, count)).start();
// -> 0:01:32.064 (92s)
new Thread(new StrippedLockWorker(readySignal, startSignal, doneSignal, i, count)).start();
}
catch(Throwable t) {
t.printStackTrace();
System.err.println(i);
}
}
readySignal.await();
stopWatch.start();
startSignal.countDown();
doneSignal.await();
stopWatch.stop();
System.err.println(stopWatch);
}
}
class GlobalLockWorker implements Runnable {
private static final Object globalLock = new Object();
private static final Map<Integer, Boolean> hash = new HashMap<Integer, Boolean>();
private final CountDownLatch readySignal;
private final CountDownLatch startSignal;
private final CountDownLatch doneSignal;
private int id;
private int count;
public GlobalLockWorker(CountDownLatch readySignal, CountDownLatch startSignal, CountDownLatch doneSignal, int id, int count) {
this.readySignal = readySignal;
this.startSignal = startSignal;
this.doneSignal = doneSignal;
this.id = id;
this.count = count;
}
@Override
public void run() {
try {
readySignal.countDown();
startSignal.await();
for(int i = 0; i < count; i++) {
synchronized (globalLock) {
hash.put(new Integer(id), true);
}
}
doneSignal.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
class StrippedLockWorker implements Runnable {
private static final Map<Integer, Boolean> hash = new ConcurrentHashMap<Integer, Boolean>();
private final CountDownLatch readySignal;
private final CountDownLatch startSignal;
private final CountDownLatch doneSignal;
private int id;
private int count;
public StrippedLockWorker(CountDownLatch readySignal, CountDownLatch startSignal, CountDownLatch doneSignal, int id, int count) {
this.readySignal = readySignal;
this.startSignal = startSignal;
this.doneSignal = doneSignal;
this.id = id;
this.count = count;
}
@Override
public void run() {
try {
readySignal.countDown();
startSignal.await();
for(int i = 0; i < count; i++) {
hash.put(new Integer(id), true);
}
doneSignal.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
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