printout times SunOS spooler ./. CUPS 1.4.3

[Helge Blischke]

Matthias Apitz wrote:

> Helge Blischke wrote:
> 
>>> lpsched: 92 secs
>>> CUPS: 203 secs
>>> 
>>> and you can hear short delays while the pages send out from CUPS get
>>> printed;
>>> 
>>> before watching the details with TCPDUMP, is there any explanation for
>>> this? note: it is only plain PCL, no PostScript gets involved;
>>> 
>>> Thanks
>>> 
>>> matthias
>> 
>> First, try appending the option
>> ?waiteof=false
>> to the device URI. That causes the socket backend not to wait until the
>> other side (the printer) closes the connection.
>> 
>> If that isn't enough, you may recompile the socket backend and disable
>> the use of the wait_bc function (which waits up to 5 seconds to drain the
>> backchannel data).
>> 
>> Or you use the hpnpf backend (see the links at wwwlcups.org) and ask me
>> for a wrapper script that turns off all waiting of this backend.
>> 
>> Helge
> 
> Helge,
> 
> Thanks for the hints. Concerning wait_bc() function call: the CUPS version
> in question is 1.4.3 and interestingly on my FreeBSD laptop in CUPS 1.4.6
> the code is already commented away in socket.c with:
> 
> #ifdef __APPLE__
>  /*
>   * Wait up to 5 seconds to get any pending back-channel data...
>   */
> 
>   wait_time = time(NULL) + 5;
>   while (wait_time >= time(&current_time))
>     if (wait_bc(device_fd, wait_time - current_time) <= 0)
>       break;
> #endif /* __APPLE__ */
> 
> I commented out the lines in 1.4.3 too; in addition I applied the
> option ?waiteof=false to the URI and now the printout matches nearly what
> the printer is able to do with moving the paper;
> 
> Concerning the applied patch, is there some risk about data loss in heavy
> busy situations?
> 
> Thanks
> 
>     matthias

If I remember the recent discussions on this issue correctly, the reason for 
this waiting was a specific property of the Mac OS X's USB driver.

For components which really rely on backchannel data, the API provides 
specific funcions for draining the backchannel.

Helge