CODEWITHSUNDEEP
pythonmultithreadingpython-2.7sleep
Ziva
Ziva

Reputation: 3501

Python: pause function but not whole program

I have two function, which generate random integer, and sleep for the given interval. However, I would like to sleep those two functions independently, while time.sleep() pauses the whole Python program. 

def fun1():
 interval1 = random.randint(2,800)
 time.sleep(interval1)
 # do other things

def fun2():
 interval2 = random.randint(1, 999)
 time.sleep(interval2)
 # do other things, different than in fun2

How I can sleep a given function, such that when fun1 is paused, fun2 still is doing their thing as long as the time.sleep(interval2) is not called?

Upvotes: 2

Views: 1561

Answers (2)

Jokab
Jokab

Reputation: 2936

Simply do like this:

from threading import Thread
thread1 = Thread(target=fun1)
thread2 = Thread(target=fun2)
thread1.start()
thread2.start()

This will start two threads which are independent of the main thread, calling fun1 and fun2 respectively.

Example:

from threading import Thread
import random
import time

starttime = time.time()

def fun1():
    interval1 = random.randint(1,5)
    time.sleep(interval1)
    print "%d sec: Fun1" % (time.time() - starttime)

def fun2():
    interval2 = random.randint(1,5)
    time.sleep(interval2)
    print "%d sec: Fun2" % (time.time() - starttime)

thread1 = Thread(target=fun1)
thread2 = Thread(target=fun2)
thread1.start()
thread2.start()

print "Still doing things!"

Output:

Still doing things!
2 sec: Fun2
4 sec: Fun1

As you can see, the functions are ran but the code still continues executing the print statement after the threads.

Upvotes: 1

Will
Will

Reputation: 24689

Try this:

from multiprocessing import Process

def fun1():
    interval1 = random.randint(2,800)
    time.sleep(interval1)
    # do other things

def fun2():
    interval2 = random.randint(1, 999)
    time.sleep(interval2)
    # do other things

proc1 = Process(target=fun1)
proc2 = Process(target=fun2)
proc1.start()
proc2.start()
proc1.join()
proc2.join()

This will start new Python processes using multiprocessing to run fun1() and fun2() in parallel. The join() calls will block in the main (parent) process until proc1 and proc2 are complete.

Unfortunately, due to the Global Interpreter Lock, the threading module doesn't help performance much. But if your functions are mostly just waiting, Threads can be appropriate.

Upvotes: 1

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