Phil Steitz created POOL-231:
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Summary: GOP, GKOP invalidateObject is not threadsafe
Key: POOL-231
URL: https://issues.apache.org/jira/browse/POOL-231
Project: Commons Pool
Issue Type: Bug
Affects Versions: Nightly Builds
Reporter: Phil Steitz
Fix For: 2.0
There does not appear to be sufficient sync protection for the destroyCount and
createCount counters when destroy is activated by invalidateObject in GOP,
GKOP, v2 trunk. The test below fails when added to GOP tests. I expected
decrementCount to be *over-incremented* by this code; but it appears to be
regularly under-incremented. I do not have a satisfying explanation for this
and it could be that the test code is flawed. We should in any case take a
close look at concurrent invalidation scenarios. This (potential) problem was
originally reported by Thomas Neidhart in a comment on POOL-213.
{code}
@Test
public void testConcurrentInvalidate() throws Exception {
// Get allObjects and idleObjects loaded with some instances
final int nObjects = 1000;
pool.setMaxTotal(nObjects);
Object[] obj = new Object[nObjects];
for (int i = 0; i < nObjects; i++) {
obj[i] = pool.borrowObject();
if (i % 2 == 0) {
pool.returnObject(obj[i]);
}
}
final int nThreads = 100;
final int nIterations = 100;
final InvalidateThread[] threads = new InvalidateThread[nThreads];
// Randomly generated list of distinct invalidation targets
final ArrayList<Integer> targets = new ArrayList<Integer>();
final Random random = new Random();
for (int j = 0; j < nIterations; j++) {
// Get a new invalidation target
Integer targ = new Integer(random.nextInt(nObjects));
while (targets.contains(targ)) {
targ = new Integer(random.nextInt(nObjects));
}
targets.add(targ);
// Launch nThreads threads all trying to invalidate the target
for (int i = 0; i < nThreads; i++) {
threads[i] = new InvalidateThread(pool, obj[targ]);
}
for (int i = 0; i < nThreads; i++) {
new Thread(threads[i]).start();
}
boolean done = false;
while (!done) {
done = true;
for (int i = 0; i < nThreads; i++) {
done = done && threads[i].complete();
}
Thread.sleep(100);
}
}
Assert.assertEquals(nIterations, pool.getDestroyedCount());
}
static class InvalidateThread implements Runnable {
final private Object obj;
final private ObjectPool<Object> pool;
private boolean done = false;
public InvalidateThread(ObjectPool<Object> pool, Object obj) {
this.obj = obj;
this.pool = pool;
}
public void run() {
try {
pool.invalidateObject(obj);
} catch (IllegalStateException ex) {
// Ignore
} catch (Exception ex) {
Assert.fail("Unexpected exception " + ex.toString());
} finally {
done = true;
}
}
public boolean complete() {
return done;
}
}
{code}
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