RFR: 8314515: java/util/concurrent/SynchronousQueue/Fairness.java failed with "Error: fair=false i=8 j=0"

[Martin Buchholz]

On Fri, 18 Aug 2023 08:18:24 GMT, Viktor Klang <duke at openjdk.org> wrote:

>> The usual tiny improvements, with no guarantee that the intermittent test failure is actually fixed.
>
> test/jdk/java/util/concurrent/SynchronousQueue/Fairness.java line 70:
> 
>> 68:                                               fair, i, threadCount, j));
>> 69:         }
>> 70:         for (Thread t : ts) t.join();
> 
> @Martin-Buchholz Makes a lot of sense to make sure that all threads have terminated before exiting the test 👍

There's a lot of infrastructure in JSR166TestCase.java to address this.  Some of it could be librarified for use by other openjdk tests.


 * <li>All code not running in the main test thread (manually spawned threads
 * or the common fork join pool) must be checked for failure (and completion!).
 * Mechanisms that can be used to ensure this are:
 *   <ol>
 *   <li>Signalling via a synchronizer like AtomicInteger or CountDownLatch
 *    that the task completed normally, which is checked before returning from
 *    the test method in the main thread.
 *   <li>Using the forms {@link #threadFail}, {@link #threadAssertTrue},
 *    or {@link #threadAssertNull}, (not {@code fail}, {@code assertTrue}, etc.)
 *    Only the most typically used JUnit assertion methods are defined
 *    this way, but enough to live with.
 *   <li>Recording failure explicitly using {@link #threadUnexpectedException}
 *    or {@link #threadRecordFailure}.
 *   <li>Using a wrapper like CheckedRunnable that uses one the mechanisms above.
 *   </ol>

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PR Review Comment: https://git.openjdk.org/jdk/pull/15337#discussion_r1299029889