[jboss-jira] [JBoss JIRA] Updated: (JBAS-4525) JBossMQ WriteTask in UIL2 could block forever

[Adrian Brock (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBAS-4525?page=all ]

Adrian Brock updated JBAS-4525:
-------------------------------

    Description: 
The JBossMQ UIL2 WriteTask shutdowns when it is signaled by the ReadTask using an Thread.interrupt().

If however, something "eats" that interrupt status of the thread then the WriteTask will block forever and never stop.
This leads to thread leaks.

The solution is not to wait forever for an interrupt. Instead the thread should periodically wake up
and check the "started" flag. e.g. Here is the suggest patch in outline

while (true)
{
+ synchronized (running)
+ {
+ if (WriteState != Started)
+ break;
+ }
BaseMsg msg = null;
try
{
- msg = (BaseMsg) sendQueue.take();
+ // Only wait for 10 seconds
+ msg = (BaseMsg) sendQueue.poll(10000l);
+ if (msg == null)
+ continue; // re-start the loop when no message after 10 seconds


  was:
The JBossMQ UIL2 WriteTask shutdowns when it is signaled by the ReadTask using an Thread.interrupt().

If however, something "eats" that interrupt status of the thread then the WriteTask will block forever and never stop.
This leads to thread leaks.

The solution is not wait forever or an interrupt. Instead the thread should periodically wake up
and check the "started" flag. e.g. Here is the suggest patch in outline

while (true)
{
+ synchronized (running)
+ {
+ if (WriteState != Started)
+ break;
+ }
BaseMsg msg = null;
try
{
- msg = (BaseMsg) sendQueue.take();
+ // Only wait for 10 seconds
+ msg = (BaseMsg) sendQueue.poll(10000l);
+ if (msg == null)
+ continue; // re-start the loop when no message after 10 seconds



> JBossMQ WriteTask in UIL2 could block forever
> ---------------------------------------------
>
>                 Key: JBAS-4525
>                 URL: http://jira.jboss.com/jira/browse/JBAS-4525
>             Project: JBoss Application Server
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: JMS service
>    Affects Versions: JBossAS-4.2.1.GA
>            Reporter: Adrian Brock
>         Assigned To: Adrian Brock
>             Fix For: JBossAS-5.0.0.GA, JBossAS-4.2.2.CR1
>
>
> The JBossMQ UIL2 WriteTask shutdowns when it is signaled by the ReadTask using an Thread.interrupt().
> If however, something "eats" that interrupt status of the thread then the WriteTask will block forever and never stop.
> This leads to thread leaks.
> The solution is not to wait forever for an interrupt. Instead the thread should periodically wake up
> and check the "started" flag. e.g. Here is the suggest patch in outline
> while (true)
> {
> + synchronized (running)
> + {
> + if (WriteState != Started)
> + break;
> + }
> BaseMsg msg = null;
> try
> {
> - msg = (BaseMsg) sendQueue.take();
> + // Only wait for 10 seconds
> + msg = (BaseMsg) sendQueue.poll(10000l);
> + if (msg == null)
> + continue; // re-start the loop when no message after 10 seconds

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