subprocess.Popen strange bhaviour

Steven D'Aprano steve+comp.lang.python at
Wed Jan 18 04:23:01 EST 2012

On Wed, 18 Jan 2012 14:44:37 +0530, Mac Smith wrote:

> Hi,
> I am using subprocess.Popen to start a movie ripping command
> HandBrakeCLI. My server is 64bit ubuntu server and has 8 cores. When the
> command starts it uses all 8 cores upto 80%-100% and works fine, but
> after 270 seconds the cpu usage of all the cores drops to 0% - 1%. I
> tried this many time this happens exactly after 270 seconds. Is there
> some predefined timeout??

I think you have misunderstood subprocess.Popen. It launches the new 
process (HandBrakeCLI) then what happens in that new process is 
independent of Python and Popen.

How are you calling HandBrakeCLI? Is it ripping directly from a device or 
file, or is it reading from stdin? If reading from stdin, possibly it is 
waiting for more data from you. Or perhaps it has simply finished ripping 
and there's nothing else for it to do and the process ends.


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