[ace-users] ACE_TP_Reactor:random crash sometimes

[Mihai Bucica]

Ok ..I've managed to simplify to the following
problem:

While one thread from the reactor thread pool
(ACE_TP_Reactor is inside the handle_input() of a
handle another thread from the reactor thread pool is
calling handle_output() on the same handle.



Is this behaviour possible? In C++NPv2 it is stated
about ACE_TP_Reactor:
"It prevents multiple I/O events from being dispatched
to the same event handler simultaneously in different
threads. This constraint preserves the I/O dispatching
behavior of ACE_Select_Reactor, alleviating the need
to add synchronization locks to a handler's I/O
processing."

I'm a little puzzled

--- Steve Huston <shuston at riverace.com> wrote:

> Hi Mihai,
> 
> It could be that the reactor is still dispatching
> notifications after
> the handler is unregistered. You can investigate two
> ways to avoid
> this:
> 
> 1. See sidebar 22 on page 94 in C++NPv2
> 2. Use event handler reference counting to avoid
> deleting a handler
> while there's a reference pending (the notify). See
> ACE News and Tips
> Newsletter from October 2005
>
(http://www.riverace.com/newsletters/October2005.htm)
> 
> Best regards,
> -Steve
> 
> --
> Steve Huston, Riverace Corporation
> Would you like ACE to run great on your platform?
> See http://www.riverace.com/sponsor.htm
> 
> 
> > -----Original Message-----
> > From: ace-users-bounces at cse.wustl.edu 
> > [mailto:ace-users-bounces at cse.wustl.edu] On Behalf
> Of Mihai Bucica
> > Sent: Tuesday, June 12, 2007 6:17 AM
> > To: ace-users at cse.wustl.edu
> > Subject: Re: [ace-users] ACE_TP_Reactor:random
> crash sometimes
> > 
> > 
> > 
> > --- "Douglas C. Schmidt"
> <schmidt at dre.vanderbilt.edu>
> > wrote:
> > > >     ACE VERSION: 5.5
> > > 
> > > ACE 5.5 is rather old, so could you please try
> > > upgrading to ACE+TAO+CIAO
> > 
> > 
> > I've compiled it the latest beta kit ACE 5.5.8 and
> the
> > issue is valid.
> > 
> > PRF:
> > 
> >     ACE_TP_Reactor:random crash sometimes 
> > 
> >     ACE VERSION: 5.5.8 (latest beta kit)
> > 
> >     HOST MACHINE and OPERATING SYSTEM:
> >       AMD Turion 64 & Windows XP Pro 32
> > 
> >     COMPILER NAME AND VERSION (AND PATCHLEVEL):
> >       Microsoft Visual C++ .NET 2003
> > 
> >     THE $ACE_ROOT/ace/config.h FILE : 
> >       #include "ace/config-win32.h"
> > 
> >     AREA/CLASS/EXAMPLE AFFECTED:
> >       ACE_TP_Reactor & Acceptor
> >  
> >     DOES THE PROBLEM AFFECT:
> >       EXECUTION
> >       
> >     SYNOPSIS:
> >       sometimes one thread from ACE_TP_Reactor'
> pool
> > is trying to access a recently removed handle 
> >     
> >     DESCRIPTION:
> >       I'm trying to build a server starting from
> > examples/APG/TreadPools/TP_Reactor project and
> I've
> > performed the following small modifications:
> >       I've added a
> 'ACE_Reactor_Notification_Strategy
> > _notifier' to our Request_Handler class and also
> done
> > the proper initialization stuff:
> >       
> >       Request_Handler: notifier_ (0, this,
> > ACE_Event_Handler::WRITE_MASK)
> >       Request_Handler::open ->
> this->notifier_.reactor
> > (this->reactor ());
> >                                this->msg_queue
> > ()->notification_strategy (&this->notifier_);   
> >    
> >       I'm also doing a strange thing in
> handle_input()
> > 
> >       int Request_Handler::handle_input() {
> >         ..............
> >         ACE_Message_Block *mb = new
> > ACE_Message_Block(sizeof(buffer)+1);
> >         mb->copy(buffer,sizeof(buffer));
> >         this->putq(mb); 
> >   
> >         return -1; 
> >       }
> >       
> >       int Request_Handler::handle_close
> (ACE_HANDLE
> > fd, ACE_Reactor_Mask)
> >       {
> >         ACE_DEBUG ((LM_DEBUG,
> >               ACE_TEXT ("(%t) svr close; fd:
> 0x%x\n"),
> >               fd));
> > 
> >         return super::handle_close();
> >       }
> > 
> >       This will cause the program to crash
> > sometimes.The 'handle' is removed from reactor and
> > deleted but another thread from the thread pool
> will
> > try to output our ACE_Message_Block object from
> the
> > event handler internal queue.   
> >       (5200) handling events ....
> >       (3672) handling events ....
> >       (5676) handling events ....
> >         Request_Handler::open
> >       (3672) handling events ....
> >       (5676) handling events ....
> >       (5200) handling events ....
> >       (3672) svr input; fd: 0x6d8; input: e
> >       (3672) svr close; fd: 0x6d8
> >       (3672) ~Request_Handler()
> >       (3672) handling events ....
> >       (5200) handling events .... !!! HERE IT
> CRASHES
> > because the thread 5200 is trying to access the
> > previous deleted Request_Handler() object because
> he
> > tries to output our ACE_Message_Block object from
> the
> > event handler internal queue !!!!
> >       
> >       
> > 
> > 
> > 
> >  
> >
>
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> > 
> 
> 
> 



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