CODEWITHSUNDEEP
pythonmultithreading
kun
kun

Reputation: 4237

how real programmer do server loop?

everytime when running this program, I hear my cpu fan is boosting. I suspected the busy waiting while loops in the code is the cause. I wonder how a real programmer will do to optimize this? 

from multiprocessing import Process, Queue
import threading
class PThread(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self)
        #view leave will set this event
        self.event = threading.Event()
    def run(self):
        while 1:
            if not self.event.is_set():
               print 'run'
            else:
               break



def server_control(queue):
    while True:
        try:
            event = queue.get(False)
        except:
            event = None
        if event == 'DETECTED':
            print 'DETECTED'
            t = PThread()
            t.start()
        elif event == 'LEAVE':
            print 'Viewer_left'
            t.event.set()
            t.join()
        elif event == 'QUIT':
                break
q=Queue()
p = Process(target=server_control, args=(q,))
p.start()
p.join()

Upvotes: 2

Views: 173

Answers (3)

pythoniku
pythoniku

Reputation: 3672

The multiprocessing module has a clone of threading's event object

from multiprocessing import Process, Event

Instead of use a Queue. You should declare event of interest in your main and pass them to other process In your case:

detected = Event()
leave = Event()
exit = Event()

Process(target=server_control, args=(detected, leave, exit))

and finally check if the event is fired or wait in your loop

Upvotes: 1

Emond
Emond

Reputation: 50682

You might make the loop a bit less tight by adding a time.sleep(0) in the loop to pass the remainder of the quantum to another thread.

See also: How does a threading.Thread yield the rest of its quantum in Python?

Upvotes: 0

Wyzard
Wyzard

Reputation: 34573

If a thread needs to wait for an event, it should sleep until the event occurs, rather than busy-waiting. Your event object has a wait() method that can be used to accomplish that. Call it, and it won't return until some other thread has called set() on the event (or the timeout elapses, if you specify one). In the meantime, the thread uses no CPU.

Upvotes: 5

Related Questions