Python: How to Run multiple programs on same interpreter

Question

How to start an always on Python Interpreter on a server?

If bash starts multiple python programs, how can I run it on just one interpreter?

And how can I start a new interpreter after tracking number of bash requests, say after X requests to python programs, a new interpreter should start.

EDIT: Not a copy of https://stackoverflow.com/questions/16372590/should-i-run-1000-python-scripts-at-once?rq=1

Requests may come pouring in sequentially

Answer 1

You cannot have new Python programs started through bash run on the same interpreter, each program will always have its own. If you want to limit the number of Python programs running the best approach would be to have a Python daemon process running on your server and instead of creating a new program through bash on each request you would signal the daemon process to create a thread to handle the task.

Answer 2

To run a program forever in python:

while True :
     do_work()

You could look at spawning threads for incoming request. Look at threading.Thread class.

from threading import Thread

task = new Thread(target=do_work, args={})
task.start()

Answer 3

You probably want to take a look at http://docs.python.org/3/library/threading.html and http://docs.python.org/3/library/multiprocessing.html ; threading would be more lightweight but only allows one thread to execute at a time (meaning it won't take advantage of multicore/hyperthreaded systems), while multiprocessing allows for true simultaneous execution but can be a bit less lightweight than threading if you're on a system that doesn't utilize lightweight subprocesses and may not be as necessary if the threads/processes spend lots of time doing I/O requests.