multithreading - join() threads without holding the main thread in python -

i have code calls threads on loop, this:

def submitdata(data):     # creating relevant command execute     command = createcommand(data)     subprocess.call(command)  def main():     while(true):         # generating data         data = getdata()         mythread = threading.thread(target=submitdata,args=(data,))          mythread.start() 

obviously, don't use join() on threads. question how join() threads without making main thread wait them? need join() them? happend if won't join() them?

some important points:

• the while loop suppose long time (couple of days)
• the command not long (few seconds)

i'm using threading performance if have better idea instead, try out.

popen() doesn't block. unless createcommand() blocks, call submitdata() in main thread:

from subprocess import popen  processes = [] while true:     processes = [p p in processes if p.poll() none] # leave running     processes.append(popen(createcommand(getdata()))) # start new 1 

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do need join() them? happend if won't join() them?

no. don't need join them. non-daemonic threads joined automatically when main thread exits.