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[Python-Dev] subprocess, buffered files, pipes and broken pipe errors

Serhiy Storchaka storchaka at gmail.com
Fri Mar 6 16:10:44 CET 2015 
On 06.03.15 14:53, Victor Stinner wrote:
> I propose to ignore BrokenPipeError in Popen.__exit__, as done in
> communicate(), for convinience:
> http://bugs.python.org/issue23570
>
> Serhiy wants to keep BrokenPipeError, he wrote that file.close()
> should not ignore write errors (read the issue for details).

I rather said about file.__exit__.

> I consider that BrokenPipeError on a pipe is different than a write
> error on a regular file.
>
> EPIPE and SIGPIPE are designed to notify that the pipe is closed and
> that it's now inefficient to continue to write into this pipe.

And into the file like open('/dev/stdout', 'wb').

> Ignoring BrokenPipeError in Popen.__exit__() respects this constrain
> because the method closes stdin and only returns when the process
> exited. So the caller will not write anything into stdin anymore.

And the caller will not write anything into the file after calling 
file.__exit__.

I don't see large difference between open('file', 'wb') and Popen('cat 
 >file', stdin=PIPE), between sys.stdout with redirecting stdout and 
running external program with Pipe().
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