python - multiprocessing.Process hangs -

edited: question needs more info...

my code launches several process one:

def my_process_executor(req, semaphore=none):     try:         p = multiprocessing.process(target=do_stuff,args=(req,))         p.daemon = false         p.start()          p.join(max_seconds_waiting_for_process)          if p.is_alive():             # time running, kill it!             p.terminate()             p.join()     finally:         if semaphore:             semaphore.release() 

when "semaphore" none, works fine, ton of concurrent processes.

but when "semaphore" has value:

semaphore = threading.boundedsemaphore(5) 

sometimes subprocess never starts. despite process.is_alive() returns true, do_stuff doesn't anything.

any idea? what's happening here?

pay attention do_stuff not check semaphore. doesn't hangs due "red light" on semaphore.

code running on ubuntu 14.04.4 lts , python 2.7