But if you know where to use them (like in this case with network I/O), they will really speed things up for you.
You will hear all kinds of stuff about how threading in Python is screwed up with the GIL and such. from the queue a thread waiting to put is notified then. It's one of the really good parts of Python. import threading from collections import deque from heapq import heappush.
Since these are deamon threads, they close down too. At that point the main thread finishes and exits. While all this is going on with the worker threads, the main thread is waiting (join) until all the tasks in the queue are done, which will be when the threads have sent the queue.task_done flag the same number of times as messages in the queue. Then, the critical part, it notifies the queue that it's done with queue.task_done, and resumes waiting for another item in the queue. When something is found, it grabs it and does its thing. Yes, your subclass puts each thread in an infinite loop, waiting on something to be put in the queue. Your script works fine for me, so I assume you are asking what is going on so you can understand it better. Print "Elapsed Time: %s" % (time.time() - start) Then, the critical part, it notifies the queue that it's done with queue.taskdone, and resumes waiting for another item in the queue. #wait on the queue until everything has been processed Yes, your subclass puts each thread in an infinite loop, waiting on something to be put in the queue. #spawn a pool of threads, and pass them queue instance #grabs urls of hosts and prints first 1024 bytes of page Does each of thread run continuously with out ending till all of them are complete? Am I missing something. We do need a thread, because we want our runner to call the queued functions from its own: the.
Python queue thread code#
I wanted to use threading in python to download lot of webpages and went through the following code which uses queues in one of the website. A thread is a flow of execution, independent from other flows.
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