Every so often you need to use a queue to manage operations in an application. Python makes this very simple. Python also, as I’ve written about before, makes threading very easy to work with. So in this quick program I’ll describe via comments, how to make a simple queue where each job is processed by a thread. Integrating this code to read jobs from a mysql database would be trivial as well; simply replace the “jobs = [..." code with a database call to a row select query.

#!/usr/bin/env python
## DATE: 2011-01-20
## FILE: queue.py
## AUTHOR: Matt Reid
## WEBSITE: http://themattreid.com
from Queue import *
from threading import Thread, Lock

'''this function will process the items in the queue, in serial'''
def processor():
    if queue.empty() == True:
        print "the Queue is empty!"
        sys.exit(1)
    try:
        job = queue.get()
        print "I'm operating on job item: %s"%(job)
        queue.task_done()
    except:
        print "Failed to operate on job"

'''set variables'''
queue = Queue()
threads = 4

'''a list of job items. you would want this to be more advanced,
like reading from a file or database'''
jobs = [ "job1", "job2", "job3" ]

”’iterate over jobs and put each into the queue in sequence”’
for job in jobs:
     print “inserting job into the queue: %s”%(job)
     queue.put(job)

”’start some threads, each one will process one job from the queue”’
for i in range(threads):
     th = Thread(target=processor)
     th.setDaemon(True)
     th.start()

”’wait until all jobs are processed before quitting”’
queue.join()