python 3 subprocess performance

[Konstantin Schukraft]

Hi,

>I've noticed the subprocess performance issue with python 3.
>For example, this simple script takes just 0,15 second to complete
>with python 2.7, but more than 5 sec with python 3.6:
>
>import subprocess
>
>for i in range(100):
>    p = subprocess.Popen(['uname', '-a'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
>    (stdoutdata, stderrdata) = p.communicate()
>
>Profiling with the cProfile shows, that this excessive 5 seconds was
>wasted in the "{built-in method posix.read}"
>
>Could anybody confirm this issue?

I see this on HardenedBSD 12 with python2.7 (fast) and python3.6 and 3.7
(both slow) installed from packages.
Interestingly, I don't see this on my FreeNAS 11.3, where python2.7 and
3.6 are both installed by default and run fast.


Hope that helps,

Konstantin
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