Call a function without waiting for it

Question

Hi I was wondering if there was a way of calling a function/method (preferably in Python or Java) and continue execution without waiting for it.

Example:

Answer 1

As noted in other answers, from Python you can either put the function in a new thread (not that good, since threads in CPython do not gain you much), or in another process using Multiprocessing -

from multiprocessing import Process

def b():
    # long process

def a():
    p = Process(target=b) 
    p.start()
    ...
a()

(As put in monkut's answer).

But Python's decorator allow one to hide the boilerplate under the carpet, in a way that at calling time, you "see" just a normal function call. In the example bellow, I create the "parallel" decorator - just place it before any function, and it will authomatically run in a separate process when called:

from multiprocessing import Process
from functools import partial

from time import sleep

def parallel(func):
    def parallel_func(*args, **kw):
        p = Process(target=func, args=args, kwargs=kw)
        p.start()
    return parallel_func

@parallel
def timed_print(x=0):
    for y in range(x, x + 10):
        print y
        sleep(0.2)



def example():
    timed_print(100)
    sleep(0.1)
    timed_print(200)
    for z in range(10):
        print z
        sleep(0.2)


if __name__ == "__main__":
    example()

When running this snippet, one gets:

[gwidion@caylus Documents]$ python parallel.py 
100
0
200
101
1
201
102
2
202
103
3
203
104
4
204
105
5
205
106
6
206
107
7
207
108
8
208
109
9
209
[gwidion@caylus Documents]$