Hi Kim,
I think there may be an issue with your test. Specifically, this code is
suspect:
// Wait for the producer thread to enter BLOCKED state
// This ensures that the thread is waiting on the full queue
while (thread.getState() == State.RUNNABLE || thread.getState() ==
State.NEW);
I don't think that actually guarantees that the thread is blocked in put().
I was able to reproduce the bug using ArrayBlockingQueue(), but could no
longer reproduce it after I changed the above code to this:
// Wait for the producer thread to block in queue.put()
// This ensures that the thread is waiting on the full queue
while (!queue.isPutting(thread));
after also making this change to ArrayBlockingQueue.java:
---
a/src/java.base/share/classes/java/util/concurrent/ArrayBlockingQueue.java
+++
b/src/java.base/share/classes/java/util/concurrent/ArrayBlockingQueue.java
@@ -365,10 +365,31 @@ public void put(E e) throws InterruptedException {
Objects.requireNonNull(e);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
+ final boolean added = puttingThreads.add(Thread.currentThread());
try {
while (count == items.length)
notFull.await();
enqueue(e);
+ } finally {
+ if (added)
+ puttingThreads.remove(Thread.currentThread());
+ lock.unlock();
+ }
+ }
+
+ private final java.util.HashSet<Thread> puttingThreads = new
java.util.HashSet<>();
+
+ /**
+ * Test for putting thread.
+ *
+ * @param thread thread to test
+ * @return true if thread is a putting thread
+ */
+ public boolean isPutting(Thread thread) {
+ final ReentrantLock lock = this.lock;
+ lock.lock();
+ try {
+ return puttingThreads.contains(thread);
} finally {
lock.unlock();
}
So the original test may not be correct due to Java memory model
subtleties, etc.
-Archie
--
Archie L. Cobbs
