CODEWITHSUNDEEP
python
xxbidiao
xxbidiao

Reputation: 874

Spawn another python process and get its return object

Say that you have a singleton to play with (which means that the only way to initialize that to original state is to restart the whole script) and you want to do a specific tasks multiple times on this and get the returned objects. Are there any ways I can do this without disk I/O? I know I can do that with subprocess.check_output() like How to spawn another process and capture output in python? and file I/O or piping stdio, but are there any cleaner solutions as simple as same-process communications (Edit: I mean, result = foo())? 

#the singleton
def foo():
    crash_when_got_run_twice()
    result = something_fancy()
    return result

#the runner
def bar(times):
    for i in range(times):
        result = magic() # run foo()
        aggregate_result(result)
    return aggregated_result()

What do you think you can do in magic()?

Upvotes: 0

Views: 135

Answers (1)

tdelaney
tdelaney

Reputation: 77337

On unix-like systems you can fork a subprocess and have it run the singleton. Assuming you've already imported everything needed by the singleton and the singleton itself doesn't touch the disk, it could work. Fair warning: whatever reason this thing was a singleton in the first place may nip you. You can let the multiprocessing package do the heavy lifting for you.

On windows, a new python interpreter is executed and there may be significant state passed between parent and child, which could have harmful effects. But again, it may work...

import multiprocessing as mp

#the singleton
def foo():
    crash_when_got_run_twice()
    result = something_fancy()
    return result

def _run_foo(i):
    return foo()

#the runner
def bar(times):
    with mp.Pool(min(mp.cpu_count(), times) as pool:
        return pool.map(_run_foo, range(times))

Upvotes: 1

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