On 11/07/2011 09:50 PM, Brian Goetz wrote:
Wait/notify may be better than sleeping, but semaphore/latch/barrier are much
better than wait/notify. Much.
Sent from my iPhone
Yeah, APIs evolve, it seems I'm to old for that s... :)
Rémi
On Nov 7, 2011, at 1:28 PM, chris hegarty<chris.hega...@oracle.com> wrote:
Hi Gary,
Thanks for taking this bug.
In similar tests I've preferred to use j.u.c.Paser/CountDownLatch to coordinate
between threads. So, you could completely remove the sleep(1000) from the run
method and use a Phaser.arriveAndAwaitAdvance(). This will guarantee both
threads will reach a particular point before invoking stop on the group. That
way, either thread can invoke stop and set the flag to prevent the other thread
from invoking stop too ( if it were to get there! ).
I agree with Rémi's comments about wait/notify. My comments (above) should work
with well with his suggestion. Then no more nasty sleeps!
Thanks,
-Chris.
On 07/11/2011 16:03, Gary Adams wrote:
Here's another test with race conditions built into the test
that can be easily avoided
CR#7084033 - TEST_BUG: test/java/lang/ThreadGroup/Stop.java fails
intermittently
There are at least two race conditions in the test as currently written.
The test uses sleeps as a way to yield time to other threads to complete
their
tasks, but this may not be sufficient on slower machines.
The first race condition is in the starting of the test threads.
To ensure both threads are started, the run check for the first thread
should
also check that the second thread is not null.
The second race condition in the main thread presumes that
the group stop has been issued within 3000 milliseconds.
A simple loop on the delay can be gated by a flag set after the group
stop has been issued.
diff --git a/test/java/lang/ThreadGroup/Stop.java
b/test/java/lang/ThreadGroup/Stop.java
--- a/test/java/lang/ThreadGroup/Stop.java
+++ b/test/java/lang/ThreadGroup/Stop.java
@@ -32,6 +32,7 @@
private static Thread first=null;
private static Thread second=null;
private static ThreadGroup group = new ThreadGroup("");
+ private static boolean groupStopped =false ;
Stop() {
Thread thread = new Thread(group, this);
@@ -47,8 +48,11 @@
while (true) {
try {
Thread.sleep(1000); // Give other thread a chance to start
- if (Thread.currentThread() == first)
+ if ((Thread.currentThread() == first)
+&& (second != null)) {
+ groupStopped = true;
group.stop();
+ }
} catch(InterruptedException e){
}
}
@@ -57,7 +61,10 @@
public static void main(String[] args) throws Exception {
for (int i=0; i<2; i++)
new Stop();
+ do {
Thread.sleep(3000);
+ } while (!groupStopped) ;
+
boolean failed = second.isAlive();
first.stop(); second.stop();
if (failed)
