[jboss-jira] [JBoss JIRA] Commented: (JGRP-536) Catching InterruptedException and setting interrupt bit in a loop might cause infinite loop

[Bela Ban (JIRA)]

    [ http://jira.jboss.com/jira/browse/JGRP-536?page=comments#action_12365501 ] 
            
Bela Ban commented on JGRP-536:
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> Catching InterruptedException and setting interrupt bit in a loop might cause infinite loop
> -------------------------------------------------------------------------------------------
>
>                 Key: JGRP-536
>                 URL: http://jira.jboss.com/jira/browse/JGRP-536
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Bela Ban
>         Assigned To: Bela Ban
>             Fix For: 2.4.1 SP4, 2.5
>
>
> FC.handleDownMessage() has the following code:
>                     while(length > lowest_credit && running) {
>                         try {
>                             boolean rc=credits_available.await(max_block_time, TimeUnit.MILLISECONDS);
>                             if(rc || length <= lowest_credit || !running)
>                                 break;
>                             long wait_time=System.currentTimeMillis() - last_credit_request;
>                             if(wait_time >= max_block_time) {
>                                 // we have to set this var now, because we release the lock below (for sending a
>                                 // credit request), so all blocked threads would send a credit request, leading to
>                                 // a credit request storm
>                                 last_credit_request=System.currentTimeMillis();
>                                 // we need to send the credit requests down *without* holding the sent_lock, otherwise we might
>                                 // run into the deadlock described in http://jira.jboss.com/jira/browse/JGRP-292
>                                 Map<Address,Long> sent_copy=new HashMap<Address,Long>(sent);
>                                 sent_copy.keySet().retainAll(creditors);
>                                 sent_lock.unlock();
>                                 try {
>                                     // System.out.println(new Date() + " --> credit request");
>                                     for(Map.Entry<Address,Long> entry: sent_copy.entrySet()) {
>                                         sendCreditRequest(entry.getKey(), entry.getValue());
>                                     }
>                                 }
>                                 finally {
>                                     sent_lock.lock();
>                                 }
>                             }
>                         }
>                         catch(InterruptedException e) {
>                             // set the interrupted flag again, so the caller's thread can handle the interrupt as well
>                             Thread.currentThread().interrupt();
>                         }
>                     }
> So if the thread is interrupted, unless 
> length < lowest_credit || !running,
> we will have an infinite loop !
> SOLUTION: we cannot set the interrupt flag again, because we *don't* return from the loop !

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