子进程：鉴于wait（）终止，communication（）是否可以超时？

Question

Is it possible for Popen.communicate(timeout=2) to raise TimeoutExpired , even though I am asserting that Popen.poll() is not None and Popen.wait(2) does not throw an exception?

Edit: The docs suggest to use the following snippet:

proc = subprocess.Popen(...)
try:
    outs, errs = proc.communicate(timeout=15)
except TimeoutExpired:
    proc.kill()
    outs, errs = proc.communicate()

but this will just raise ProcessLookupError: [Errno 3] No such process . Which makes sense because I've already terminated the process via poll and wait .

Answer 1

Yes. It is possible if the child spawns its own subprocesses. Popen.communicate() may return much later than Popen.wait() which waits only for the child. See Python subprocess' check_call() vs check_output() .

Note: proc.kill() might not kill the whole process tree. See How to terminate a python subprocess launched with shell=True .