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Evaluation
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The System.sleep(100) is un unreliable way to serialize thread execution.
Some other j.u.c. mechanisms need to be used to guarantee serial execution.
Consider using an array of ReentrantLocks or CountdownLatches
Posted Date : 2007-11-22 00:13:42.0
Here's the proposed patch:
diff --git a/test/java/util/concurrent/SynchronousQueue/Fairness.java b/test/java/util/concurrent/SynchronousQueue/Fairness.java
--- a/test/java/util/concurrent/SynchronousQueue/Fairness.java
+++ b/test/java/util/concurrent/SynchronousQueue/Fairness.java
@@ -23,36 +23,49 @@
/*
* @test
- * @bug 4992438
- * @compile -source 1.5 Fairness.java
- * @run main Fairness
+ * @bug 4992438 6633113
* @summary Checks that fairness setting is respected.
*/
import java.util.concurrent.*;
+import java.util.concurrent.locks.*;
public class Fairness {
private static void testFairness(boolean fair,
final BlockingQueue<Integer> q)
- throws Exception
+ throws Throwable
{
- for (int i = 0; i < 3; i++) {
- final Integer I = new Integer(i);
- new Thread() { public void run() {
- try { q.put(I); } catch (Exception e) {}
- }}.start();
- Thread.currentThread().sleep(100);
+ final ReentrantLock lock = new ReentrantLock();
+ final Condition ready = lock.newCondition();
+ final int threadCount = 10;
+ final Throwable[] badness = new Throwable[1];
+ lock.lock();
+ for (int i = 0; i < threadCount; i++) {
+ final Integer I = i;
+ Thread t = new Thread() { public void run() {
+ try {
+ lock.lock();
+ ready.signal();
+ lock.unlock();
+ q.put(I);
+ } catch (Throwable t) { badness[0] = t; }}};
+ t.start();
+ ready.await();
+ // Probably unnecessary, but should be bullet-proof
+ while (t.getState() == Thread.State.RUNNABLE)
+ Thread.yield();
}
- for (int i = 0; i < 3; i++) {
- int j = q.take().intValue();
- System.err.printf("%d%n",j);
+ for (int i = 0; i < threadCount; i++) {
+ int j = q.take();
// Non-fair queues are lifo in our implementation
- if (fair ? j != i : j != 2-i)
- throw new Exception("No fair!");
+ if (fair ? j != i : j != threadCount - 1 - i)
+ throw new Error(String.format("fair=%b i=%d j=%d%n",
+ fair, i, j));
}
+ if (badness[0] != null) throw new Error(badness[0]);
}
- public static void main(String[] args) throws Exception {
+ public static void main(String[] args) throws Throwable {
testFairness(false, new SynchronousQueue<Integer>());
testFairness(false, new SynchronousQueue<Integer>(false));
testFairness(true, new SynchronousQueue<Integer>(true));
Posted Date : 2008-03-06 23:57:51.0
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