[ace-users] ACE_TP_Reactor:random crash sometimes
Douglas C. Schmidt
schmidt at dre.vanderbilt.edu
Tue Jun 12 07:52:36 CDT 2007
Hi Mihai,
That behavior shouldn't be happening in general, but without seeing
your sample program it's hard to know what's going on. Can you post a
very simple example that illustrates what's happening?
Thanks,
Doug
> 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 !!!!
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> ______________________________________________________________
> > > ______________________
> > > Never miss an email again!
> > > Yahoo! Toolbar alerts you the instant new Mail
> > arrives.
> > >
> > http://tools.search.yahoo.com/toolbar/features/mail/
> > >
> > > _______________________________________________
> > > ace-users mailing list
> > > ace-users at mail.cse.wustl.edu
> > >
> > http://mail.cse.wustl.edu/mailman/listinfo/ace-users
> > >
> >
> >
> >
>
>
>
> ___________________________________________________________________________________
> You snooze, you lose. Get messages ASAP with AutoCheck
> in the all-new Yahoo! Mail Beta.
> http://advision.webevents.yahoo.com/mailbeta/newmail_html.html
>
> _______________________________________________
> ace-users mailing list
> ace-users at mail.cse.wustl.edu
> http://mail.cse.wustl.edu/mailman/listinfo/ace-users
More information about the Ace-users
mailing list