[jboss-jira] [JBoss JIRA] Closed: (JBCOMMON-41) ClassLoader leak in BasicThreadPool

[Brian Stansberry (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBCOMMON-41?page=all ]

Brian Stansberry closed JBCOMMON-41.
------------------------------------

    Resolution: Done

Added a pluggable ClassLoaderSource property, from which the pool gets a CL to set as TCCL when creating a pool thread or returning one to the pool.  To ensure backwards compatibility, if no ClassLoaderSource is injected, the handling of the TCCL is unchanged from previous releases.

> ClassLoader leak in BasicThreadPool
> -----------------------------------
>
>                 Key: JBCOMMON-41
>                 URL: http://jira.jboss.com/jira/browse/JBCOMMON-41
>             Project: JBoss Common
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: common-core
>    Affects Versions: 2.2.3.GA
>            Reporter: Brian Stansberry
>         Assigned To: Brian Stansberry
>             Fix For: 2.2.4.GA
>
>
> BasicThreadPool leaks the TCCL of whatever thread is executing when it needs to add threads to the pool.  When it's ThreadPoolExecutor needs another thread to handle a task, it calls BasicThreadPool.ThreadPoolThreadFactory.newThread(Runnable) which does this:
> String threadName = BasicThreadPool.this.toString() + "-" + lastThreadNumber.incrementAndGet();
> Thread thread = new Thread(threadGroup, runnable, threadName);
> thread.setDaemon(true);
> return thread;
> The new thread will inherit the TCCL from the old one. Nothing ever clears the TCCL from the pooled thread.
> A couple possible solutions come to mind:
> 1) Set the new thread's TCCL to null in ThreadPoolThreadFactory.newThread()
> 2) Subclass ThreadPoolExecutor, override the afterExecute() method, and set the TCCL to null there. The afterExecute() method is invoked at the completion of each task.
> The latter seems preferable, or perhaps both.  A question is whether they should set the TCCL to BasicThreadPool.class.getClassLoader() instead of null.  That doesn't sound right though.

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