[Freeswitch-users] failed to wait for I/O

Troy Anderson freeswitch at tlainvestments.com
Tue Nov 16 21:22:02 PST 2010 

Thanks!

I was getting pressure from the client, so I downgraded to openzap.  I looked at the code there, though, and it does the same thing, so it will be interesting to see if it exhibits the same issue.  If it does, I'll get the updated freetdm in place and see if that fixes it.

Is it possible that the interrupt was just reporting something else bad, and that the messages from freetdm are just symptoms, and not the cause?

-Troy

On Nov 16, 2010, at 9:42 PM, Moises Silva wrote:

> That is good enough. I committed a patch that should fix it, try git pull please.
> 
> Moises Silva
> Senior Software Engineer
> Sangoma Technologies Inc. | 100 Renfrew Drive, Suite 100, Markham ON L3R 9R6 Canada
> t. 1 905 474 1990 x128 | e. moy at sangoma.com
> 
> 
> On Sun, Nov 14, 2010 at 7:10 PM, Troy Anderson <freeswitch at tlainvestments.com> wrote:
> I've been looking deeper into this, and it seems that poll() in zt_wait ftmod_zt.c is returning EINTR, which means it was interrupted by a signal while in the system call (as the error points out).  After STFW for a while, the advice is to immediately call poll() again if receiving an EINTR.  I would patch the code and try it, but the only place I'm experiencing this is in a busy installation, and I don't want to risk the downtime before getting some feedback as the the viability of such an approach.
> 
> In addition, I am not familiar enough with linux signals to be sure this is a good idea.  Is there a way to find out what signal is interrupting the system call?  That may be helpful in determining what's going on here.
> 
> Here's the patch I'm considering:
> 
> --- a/libs/freetdm/src/ftmod/ftmod_zt/ftmod_zt.c
> +++ b/libs/freetdm/src/ftmod/ftmod_zt/ftmod_zt.c
> @@ -885,7 +885,8 @@ static FIO_WAIT_FUNCTION(zt_wait)
>        memset(&pfds[0], 0, sizeof(pfds[0]));
>        pfds[0].fd = ftdmchan->sockfd;
>        pfds[0].events = inflags;
> -       result = poll(pfds, 1, to);
> +       while ((result = poll(pfds, 1, to)) < 0 && errno == EINTR)
> +    continue;
>        *flags = 0;
> 
>        if (pfds[0].revents & POLLERR) {
> 
> Any thoughts?
> 
> Thanks,
> Troy
> 
> On Nov 12, 2010, at 10:26 AM, Anthony Minessale wrote:
> 
> > sigh, another case of DAHDI issues.
> >
> >
> > On Fri, Nov 12, 2010 at 10:25 AM, Troy Anderson
> > <freeswitch at tlainvestments.com> wrote:
> >> Thanks for the code change providing additional diagnostics.  I finally saw another call drop, but didn't have full logging on at the time.  The additional logging provided the following:
> >>
> >> 2010-11-12 11:12:54.906656 [ERR] ftmod_zt.c:904 [s1c23][1:23] Failed to poll DAHDI device: Interrupted system call
> >> 2010-11-12 11:12:54.906656 [ERR] ftmod_zt.c:904 [s1c19][1:19] Failed to poll DAHDI device: Interrupted system call
> >> 2010-11-12 11:12:54.906656 [WARNING] mod_freetdm.c:660 failed to wait for I/O
> >> 2010-11-12 11:12:54.906656 [WARNING] mod_freetdm.c:660 failed to wait for I/O
> >> 2010-11-12 11:12:54.906656 [ERR] ftmod_zt.c:904 [s1c20][1:20] Failed to poll DAHDI device: Interrupted system call
> >> 2010-11-12 11:12:54.906656 [WARNING] mod_freetdm.c:660 failed to wait for I/O
> >> 2010-11-12 11:12:54.906656 [ERR] ftmod_zt.c:904 [s1c21][1:21] Failed to poll DAHDI device: Interrupted system call
> >> 2010-11-12 11:12:54.906656 [WARNING] mod_freetdm.c:660 failed to wait for I/O
> >>
> >> I'll turn up logging and see what shows up next time, but any ideas on what may cause this?
> >>
> >> Thanks!
> >> Troy
> >>
> >> On Nov 6, 2010, at 2:17 PM, Moises Silva wrote:
> >>
> >>> On Fri, Nov 5, 2010 at 12:58 PM, Troy Anderson
> >>> <freeswitch at tlainvestments.com> wrote:
> >>>> We have an installation with a dual PRI and lots of call volume.  Among many successful calls each day, we have been experiencing a one or two dropped per day, and they always coincide with a "failed to wait for I/O" warning from mod_freetdm.  I have attempted to track down the root cause in the source and by poring over the logs, but cannot figure it out.  I have included the redacted logs here.  The log file in question is 10MB and has lots of call data that doesn't relate - I know I risked removing something important, but I tried to put in all the data related to this call.
> >>>>
> >>>> I appreciate any insights or advice on tracking this down.
> >>>>
> >>>
> >>> If you update your git tree you will be able to get more information
> >>> the next time it happens. I added some code to print the reason for
> >>> that error to happen.
> >>>
> >>> Moises Silva
> >>> Senior Software Engineer
> >>> Sangoma Technologies Inc. | 100 Renfrew Drive, Suite 100, Markham ON
> >>> L3R 9R6 Canada
> >>> t. 1 905 474 1990 x128 | e. moy at sangoma.com
> >>>
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> >
> >
> >
> > --
> > Anthony Minessale II
> >
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