On 28Feb2020 19:24, Kenzi <kenzi....@gmail.com> wrote:
I have a question regarding a simple code snippet in Python:
from subprocess import check_output
for i in range(1024):
check_output(['/bin/bash', '-c', 'echo 42'], close_fds=True)
*I wonder why running it in Python 3.7 is much faster than Python 2.7? *
(Python 3.7 is still faster, after I used *xrange * in Python 2.7)
On a lot of UNIX systems you can use the strace command to inspect what
is happening. I am personally surprised there's a significant difference
between the Pythons because I'd expect the expense of invoking bash to
dominate the cost here (consider using /bin/sh, which on many systems
isn't bash but something smaller/faster for noninteractive shell
scripting).
Write a script running just the check_output() call one, and strace it:
strace python -c "from subprocess import check_output; check_output(['/bin/bash',
'-c', 'echo 42'], close_fds=True)"
See if your 2 Pythons are doing something difference at the system call
level.
Cheers,
Cameron Simpson <c...@cskk.id.au>
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