My main problem is that I really don’t know how to implement multiprocessing.queue correctly, you cannot really instantiate the object for each process since they will be separate queues, how do you make sure that all processes relate to a shared queue (or in this case, queues)
This is a simple example of a reader and writer sharing a single queue… The writer sends a bunch of integers to the reader; when the writer runs out of numbers, it sends ‘DONE’, which lets the reader know to break out of the read loop.
from multiprocessing import Process, Queue
import time
import sys
def reader_proc(queue):
## Read from the queue; this will be spawned as a separate Process
while True:
msg = queue.get() # Read from the queue and do nothing
if (msg == 'DONE'):
break
def writer(count, queue):
## Write to the queue
for ii in range(0, count):
queue.put(ii) # Write 'count' numbers into the queue
queue.put('DONE')
if __name__=='__main__':
pqueue = Queue() # writer() writes to pqueue from _this_ process
for count in [10**4, 10**5, 10**6]:
### reader_proc() reads from pqueue as a separate process
reader_p = Process(target=reader_proc, args=((pqueue),))
reader_p.daemon = True
reader_p.start() # Launch reader_proc() as a separate python process
_start = time.time()
writer(count, pqueue) # Send a lot of stuff to reader()
reader_p.join() # Wait for the reader to finish
print("Sending {0} numbers to Queue() took {1} seconds".format(count,
(time.time() - _start)))