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https://issues.apache.org/jira/browse/POOL-396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17366675#comment-17366675
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Jeremy Kong commented on POOL-396:
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No worries! That's good to hear. Yep, rethrowing seems reasonable - I've added
that.
> 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: 0.5h
> 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
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