High CPU usage when using multicast with Python

Question

I'm programming a little multi-protocol image streaming server (in Python), and all protocols work well enough, except for the Multicast protocol that makes my CPU usage go up to 150% !

Here's the multicast code:

       delay = 1./self.flux.ips
    imgid = 0
    lastSent = 0

    while self.connected:

        #self.printLog("Getting ready to fragment {}".format(imgid))
        fragments = fragmentImage(self.flux.imageFiles[imgid], self.fragmentSize)
        #self.printLog("Fragmented {} ! ".format(imgid))

        # Checking if the delay has passed, to respected the framerate
        while (time.time() - lastSent) < delay:
            pass

        # Sending the fragments
        for fragmentid in range(len(fragments)):
            formatedFragment = formatFragment(fragments[fragmentid], fragmentid*self.fragmentSize, len(self.flux.imageFiles[imgid]), imgid)
            self.sendto(formatedFragment, (self.groupAddress, self.groupPort))

        lastSent = time.time()

        imgid = (imgid + 1) % len(self.flux.images)

The UDP protocol also sends images as fragments, and I don't have any CPU usage problems. Note that the client also have some latency to get those images.

Answer 1

Use time.sleep(delay) instead of the (heavy) busy waiting and you should be good (see this question Python: Pass or Sleep for long running processes? ).

For an even better performance you should consider an I/O event reactor like PyUV , gevent , tornado or twisted .