[hylafax-devel] Re: faxq maxing out CPU - let's crack this!!!!!

[Frank Warmerdam <warmerda@home.com>]

Darren Nickerson wrote:
> 
> >>>>> On Mon, 20 Mar 2000, "Frank" == Frank Warmerdam wrote:
> 
>   Frank> Darren,
> 
>   Frank> The mmap() support in libtiff isn't widely used, but to the best of
>   Frank> my knowledge it hasn't changed significantly lately.  Can you try
>   Frank> running hylafax without TIFF mmap enabled, and see if the problem
>   Frank> still occurs?
> 
> Not sure . . . how would I accomplish this?

Darren,

According to information in tif_open.c, you can add the "m" flag to 
the access string to TIFFOpen() to disable use of mmap().  Based on the
more recent email it seems doubtful that the problem is related to mmap()
support. 

>   Frank> There _are_ significant bugs in libtiff 3.5.4 with Fax3 compression
>   Frank> which I think are now fixed.  If you suspect this is the problem you
>   Frank> might want to try testing with the latest libtiff source from cvs (see
>   Frank> www.libtiff.org for details), for just replace your tif_fax3.c with
>   Frank> the code at:
> 
>   Frank> http://gdal.velocet.ca/~warmerda/tif_fax3.c
> 
> I'll do this - thanks.

Based on the recent email it does seem that fax3 support is the problem.  It
seemed from the email that HylaFax had it's own copy tif_fax3.c, is that right?
The libtiff tif_fax3 has been substantially upgraded - using 32bit buffers
for runs and if you (HylaFax) are assuming intimate knowledge of
the internals of libtiff's fax support, we may have found the source of
problems. 
 
>   Frank> Let me know if there is anything else Mike and I can do to help with
>   Frank> this.
> 
> Thanks for being at the end of the wire! Are you familiar with HylaFAX at all?

I once downloaded it and skimmed it but never actually tried to get it working.
I gather it was written by Sam, and shares fax encoding/decoding needs with
libtiff.  If necessary I could download and install it, but I don't really
want to try and get it working with real fax devices.

Best regards,

---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerda@home.com
light and sound - activate the windows | http://members.home.com/warmerda
and watch the world go round - Rush    | Geospatial Programmer for Rent


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