On 08/11/2019 17:05, Roman Kagan wrote:
> On Fri, Nov 08, 2019 at 01:49:50PM +0000, Vladimir Sementsov-Ogievskiy wrote:
>> 01.11.2019 19:54, Andrey Shinkevich wrote:
>>> +def check_proc_NBD(proc, connector):
>>> + try:
>>> + exitcode = proc.wait(timeout=10)
>>> +
>>> + if exitcode < 0:
>>> + log('NBD {}: EXIT SIGNAL {}\n'.format(connector, -exitcode))
>>> + log(proc.communicate()[0])
>>> + else:
>>> + line = proc.stdout.readline()
>>
>>
>> could we use proc.communicate() for both cases, what is the difference?
>
> In fact if proc produces any non-trivial amount of output you are better
> off using .communicate() otherwise your child may block on output and
> never exit. See
> https://docs.python.org/3/library/subprocess.html#subprocess.Popen.communicate
> for how to express the above logic correctly. The exit code *after*
> .communicate is available in .returncode.
>
The pattern by the link above does not work (Python3):
proc = subprocess.Popen(...)
try:
outs, errs = proc.communicate(timeout=15)
except TimeoutExpired:
proc.kill()
outs, errs = proc.communicate()
as 'proc' cannot be used for output after being killed. It results in
another exception being raised.
Andrey
>>
>>> + log('NBD {}: {}'.format(connector, line.rstrip()))
>>> +
>>> + except subprocess.TimeoutExpired:
>>> + proc.kill()
>>> + log('NBD {}: ERROR timeout expired'.format(connector))
>>> + finally:
>>> + if connector == 'server':
>>> + os.remove(nbd_sock)
>>> + os.remove(conf_file)
>
> Roman.
>
--
With the best regards,
Andrey Shinkevich
