Re: [hylafax-users] sendfax sometimes hangs, can't identify protocol?

[Mark Hunting <mark@xxxxxxxxxx>]

Hello Aidan,

Thanks a lot for your anwser! I don't have the slightest idea if I use 
triggers or JWAIT. I just call sendfax, usually from a perl script. Is 
that answer enough or do you want me to find out if I use triggers? 
Please let me know how to do that if that information is important.

If I can find the time (and a spare server + Eicon card...) I'll try to 
get the CVS version working. But a problem here is that the server must 
be stable enough for production (without production I don't know if the 
bug is still present). Another problem is that I use Debian and like 
apt-get. Building a Debian source package is doable for me but building 
and installing Hylafax from CVS is another story. It will take me some 
time. But I hope I can try it soon.

Is the bug you talk about also present in the version I use now, 4.3.1?

Thanks again,
Mark

Aidan Van Dyk wrote:
> Mark,
>
> Are you using triggers at all or JWAIT (which use triggers internally)?
> It looks as if faxq has just "lost" track of the job that that
> particular hfaxd has submitted.  The only way I know of that to happen
> is the trigger bug which has been fixed recently (but is a bug in 4.3.3
> yet).
>
> Also - the slowness of the faxq process when handling large queues is a
> well know deficiency of the scheduler in faxq.  If you're interested in
> handling large queues (with or without batching), I would recommend you
> try out current CVS.   You can get a snapshot of it from:
> 	ftp://ftp.hylafax.org/source/hylafax-SNAPSHOT.tar.gz
> or, get it straight from CVS:
> 	:pserver:cvs:cvs@xxxxxxxxxxxxxxx:/cvsroot 
> or from GIT:
> 	git://cvs.hylafax.org/HylaFAX
>
> For busy queues with all devices almost always busy, the new scheduler
> is essentially O(1), where as the original HylaFAX scheduler was O(N),
> and the one in 4.3 is O(N**2).
>
> * Mark Hunting <mark@xxxxxxxxxx> [070508 06:33]:
>   
> > The server is very busy today, and I already have a new hanging sendfax 
> > process now. I hangs almost an hour now, and I guess it will never 
> > finish anymore:
> >
> > strace -p26875
> > uucp     26875  0.0  0.1   4152  1664 ?        S    11:42   0:00 
> > /usr/bin/sendfax -m -T 3 -I 300 -n -k now + 3 days -P 128 -f 
> > xxxxxx@xxxxxxxxxxxxx -d 084xxxxxxx 92726.pdf
> >
> > This is the strace:
> >
> > Process 26875 attached - interrupt to quit
> > read(3,
> >
> > Under normal circumstances the last line becomes something like
> >
> > read(3, "200 Job 118161 submitted.\r\n", 1024) = 27
> > etc...
> >
> > And here is the strace of the corresponding hfaxd process:
> >
> > strace -p26876
> > Process 26876 attached - interrupt to quit
> > select(5, [0 4], [], [], NULL
> >
> > Which under normal circumstances becomes something like
> >
> > select(5, [0 4], [], [], NULL***)          = 1 (in [4])
> > read(4, "S*\0", 2047)                   = 3
> > read(4, 0xbfb03500, 2047)               = -1 EAGAIN (Resource 
> > temporarily unavailable)
> > write(1, "200 Job 119050 submitted.\r\n", 27) = 27
> > fcntl64(0, F_SETFL, O_RDWR|O_NONBLOCK)  = 0
> > etc...
> >
> > I also notice that adding faxes to the queue (using sendfax) is always 
> > very slow when the queue is long (7000+ faxes). It becomes so slow that 
> > the queue never becomes bigger than +/- 8000 faxes. At that point adding 
> > faxes to the queue (from my perl loop) goes at the same speed as the 
> > sending of the faxes itself using 60 phone lines. In the past this 
> > problem was even worse, until I set MaxBatchJobs to 1. I don't know why 
> > adding faxes is still slow now when the queue is long. When I do a 
> > strace on those slow processes, they hang for some seconds (or longer) 
> > at the same point as the straces above. Apparently sometimes these slow 
> > processes are not only slow, but hang forever. Slow processes are no 
> > problem, but the faxes should be sent at some point, and not hang forever.
> >
> > I hope you can help me with this problem. Please let me know if you need 
> > more information.
> >
> > Best regards,
> > Mark
> >     
>
>
>
>   

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