flexfax: faxq hanging - some progress

[Neal Holtz <nholtz@docuweb.ca>]

There have been a few reports of faxq hanging, using 100% of CPU
and doing nothing useful.  I encountered the same problem,
with 4.1beta2 on a Caldera OpenLinux 1.2 system.  I compiled
the binaries with gcc version 2.7.2.3.

I traced the problem to logic that is looking for trailing whitespace
in pages.  Attach gdb to the running faxq process and CTRL-C it a
few times, you get the following backtrace:

> 0x805a340 in G3Decoder::decodeRow (this=0xbffff280, scanline=0x0, lastx=1728) at G3Decoder.c++:228
> 228             EXPAND1D(Nop1d);
> (gdb) bt
> #0  0x805a340 in G3Decoder::decodeRow (this=0xbffff280, scanline=0x0, lastx=1728) at G3Decoder.c++:228
> #1  0x804fe7c in MemoryDecoder::scanPageForBlanks (this=0xbffff280, fillorder=2, params=@0xbffff3d8)
>     at faxQueueApp.c++:858
> #2  0x804ff60 in faxQueueApp::preparePageChop (this=0x80a8338, req=@0x80ae540, tif=0x80ae6a8, 
>     params=@0xbffff3d8, pagehandling=@0x80ae5f8) at faxQueueApp.c++:881
> #3  0x804f9ed in faxQueueApp::preparePageHandling (this=0x80a8338, req=@0x80ae540, info=@0x80aead8, 
>     dci=@0x80a1834, emsg=@0x80ae5e8) at faxQueueApp.c++:703
> #4  0x804f69f in faxQueueApp::prepareJob (this=0x80a8338, job=@0x80ae3a0, req=@0x80ae540, 
>     info=@0x80aead8, dci=@0x80a1834) at faxQueueApp.c++:578
> ... etc

Now, that EXPAND1D macro is large, and I have not looked for the real
cause
in there (and I may not), but it at least allowed me to configure a work 
around.  Put the following in  /var/spool/fax/etc/config:

PageChop:               none

Strangely - this hanging only happens when I ask for a cover page, yet
it did
not appear to be when processing the cover page, but I could be wrong
about that.

Hope this helps.




-- 
Neal Holtz                             http://www.docuweb.ca/~nholtz
Dept. of Civil and Environmental Engineering,   Carleton University,   
Ottawa, Ontario, Canada K1S 5B6.                   nholtz@docuweb.ca