Python: Run 2 processes in parallel then wait for all with timeout

Question

Looking for some best practices for the following python3 task:

• run process program1 in non-blocking mode
• run process program2 in non-blocking mode
• wait for all or kill them after timeout exceeded

I reckon I know how to do it for 1 process:

import subprocess
p = subprocess.Popen('program1', shell=True)
try:
    stdout, stderr = p.communicate(timeout=200)
except subprocess.TimeoutExpired as t:
    print(t)
    p.kill()
    outs, errs = p.communicate()

However I can't expand this approach for 2-processes case, because p.communicate blocks until program1 ends or timeout exceeds.

Also I'd like to know immediately if one of the programs fails.

Python3, OS Linux

UPD I need to implement it wisely, without any busy loops, threads etc

Answer 1

Process has a join() method similar to threads. So, in your case:

proc_1 = Process(target=my_func_1)
proc_2 = Process(target=my_func_2)

for proc in [proc_1, proc_2]:
    proc.start()

# They are doing their thing and when they've completed they will join the 
# main process and your main program can resume
for proc in [proc_1, proc_2]:
    proc.join()