[
https://issues.apache.org/jira/browse/POOL-396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17364356#comment-17364356
]
Phil Steitz commented on POOL-396:
----------------------------------
After sleeping on this, I think it is probably better to go ahead and destroy
the instance before rethrowing the exception. We should also not decrement the
numtests counter in this case.
We should probably add prominent docs somewhere (site and javadoc) pointing out
that factory methods should handle their own exceptions. We try to do
reasonable things when they throw, but this case is a good example where we
need the factory to tell us what to do.
> Exceptions in validation can cause an object's lifecycle to be stuck in
> EVICTION state
> --------------------------------------------------------------------------------------
>
> Key: POOL-396
> URL: https://issues.apache.org/jira/browse/POOL-396
> Project: Commons Pool
> Issue Type: Bug
> Affects Versions: 2.4.2, 2.9.0
> Reporter: Jeremy Kong
> Priority: Major
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently, if validation of an object throws an exception when testing an
> idle object during eviction, an exception will be thrown from the evict()
> method. This causes the object to be left in the EVICTION state, but still be
> present in the idleObjects queue.
> Future runs of the eviction thread will run into an infinite loop, because
> they pick up the afflicted object from the queue, fail to set its state to
> EVICTION, don't count it as a test, and repeat ad infinitum. This infinite
> loop means that no further evictions will take place; it also causes
> increases in garbage collection owing to allocation of the EvictionIterator
> on each loop iteration.
> This test added to TestGenericObjectPool (plus a small change allowing
> exceptions to be thrown from the validateObject method of SimpleFactory)
> reproduces the issue.
> {code:java}
> @Test
> @Timeout(value = 60000, unit = TimeUnit.MILLISECONDS)
> public void testExceptionInValidationDuringEviction() throws Exception {
> genericObjectPool.setMaxIdle(1);
> genericObjectPool.setMaxTotal(2);
> genericObjectPool.setNumTestsPerEvictionRun(1);
> genericObjectPool.setMinEvictableIdleTime(Duration.ofMillis(0));
> genericObjectPool.setTestWhileIdle(true);
> String active = genericObjectPool.borrowObject();
> genericObjectPool.returnObject(active);
> simpleFactory.setThrowExceptionOnValidate(true);
> try {
> genericObjectPool.evict();
> } catch (Exception e) {
> // OK that a given run fails. But the object should still be evicted.
> }
> genericObjectPool.evict(); // currently fails: causes an infinite loop!
> assertEquals(0, genericObjectPool.getNumActive());
> assertEquals(0, genericObjectPool.getNumIdle());
> }
> {code}
> It seems that protection against exceptions thrown by validation code exist
> elsewhere (e.g. in borrowObject()); similarly, protections against exceptions
> thrown by user eviction policy code exist in evict(). So it looks like the
> testWhileIdle() portion of evict() needs to similarly be protected.
> Thanks!
> Jeremy
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
