[cups.development] Filter and Port monitor execution order

[Michael Sweet]

On Jul 15, 2011, at 1:37 AM, keens312 wrote:
> Hi Michael,
> 
> I made a test on our non-raster CUPS drver:
> 1. Both my filter and port monitor add sleep and create a file at tmp folder
> 2. Check the files timestamp, found that the port monitor created the file at first, then the filter.
> 
> I feel like port monitor is running before the filter.
> But CUPS log shows filter was launched at first, then the port monitor.
> 
> Could you please help to confirm which one get the chance to run at first?


The filter is forked by cupsd first, however the order of execution is entirely dependent on the OS and filter in question. The only guarantee is that the output from the filter will be sent to the standard input of the port monitor.

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Michael Sweet, Senior Printing System Engineer, PWG Chair