[jira] [Resolved] (POOL-303) GenericObjectPool's borrowObject may stuck if create() always fail

["Mark Thomas (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/POOL-303?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mark Thomas resolved POOL-303.
------------------------------
       Resolution: Fixed
    Fix Version/s: 2.4.3

Thanks for the report. I created a test case and, as a result, tweaked the suggested fix. I also fixed the similar issue for GKOP.

> GenericObjectPool's borrowObject may stuck if create() always fail
> ------------------------------------------------------------------
>
>                 Key: POOL-303
>                 URL: https://issues.apache.org/jira/browse/POOL-303
>             Project: Commons Pool
>          Issue Type: Bug
>            Reporter: Phil Yang
>             Fix For: 2.4.3
>
>         Attachments: 303.txt
>
>
> If GenericObjectPool's user use borrowObject() to get the object. The pool will try to pollFirst() first and if there is no idle object it will try to create it. In create()  if createCount > maxTotal, it will not create any object and wait on idleObjects.takeFirst() or idleObjects.pollFirst(borrowMaxWaitMillis, TimeUnit.MILLISECONDS) for other thread return an object. 
> If there are many threads (the number is more than maxTotal) to borrowObject concurrently, there will only maxTotal threads go to create the object, the others will wait on the queue. However, if the factory has some problem that makeObject() always throw Exception, there will not be any object created so no thread will return the object that should send a signal to one waiting thread. The thread wait on idleObjects.takeFirst()  will stuck forever because it has no timeout.
> I think it can be fixed by adding a idleObjects.interuptTakeWaiters(); in create() before it throws the exception and let the waiting threads interrupted and retry to create.  
> It seems that all 2.x version affected?



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