running multiple commands in a parallel pool

[Skaperen]

i would like to run multiple commands in a parallel pool. i do not need to wait for the commands to be started or to end. i need to be able to set the pool size at least in advance to limit the concurrency. i need to be able to submit commands after they start running. when a command finishes, it needs to start the next one with no action needed by my code. after submitting the last command i need to wait for everything to be done. commands are in the form of a list of strings like in subprocess.Popen(). surely, something like this has been created, already.