From: Charles Hixson <charleshi...@earthlink.net>
I want to process a bunch of processes that all talk to each other. I've
figured out how to do this using queues with the main process as the mail
handler, but I'd rather have them talk directly. If I use connections, then I
can pass the pipes to the processes, but there doesn't seem to be anything
analogous to queue, so it looks like I need to divide each process into two
threads, one of which does nothing but mail handling.
Is this correct?
FWIW, a small, unoptimized, test of the working "mailhandler" approach is:
## Multiprocessing: main thread as post office.
# This is a bit clumsy, but it works.
from multiprocessing import Process, Queue from queue import Empty
def f(i, lim, q_rcv, q_snd):
for j in range(lim):
if i != j:
q_snd.put([i, "message from process {0} to proess
{1}".format(i, j), j])
if not q_rcv.empty():
val = q_rcv.get()
print (val)
q_snd.put([i, "done"])
while (not q_recv.empty()):
val = q_rcv.get()
print (val, " :: ", i)
if val == "done": return
if __name__ == '__main__':
ps = []
qs = []
q_recv = Queue()
for i in range(3):
q = Queue()
qs.append (q)
ps.append (Process(target=f, args=(i, 3, q, q_recv)) )
for p in ps:
p.start()
dones = 0
try:
v = q_recv.get(True, 1)
while (v):
print ("v = ", v)
if v[1] == "done":
dones = dones + 1
else:
if len(v) == 3:
assert v[2] < len(qs), "unexpected value"
qs[v[2]].put(v[1])
else:
print ("error: ", v, " was an unexpected value.")
v = q_recv.get(True, 1)
except Empty:
print ("1: Timeout of maine receive queue")
for q in qs:
q.put("done")
try:
v = q_recv.get(True, 1)
while (v):
print ("2: v = ", v)
if v[1] == "done":
dones = dones + 1
else:
if len(v) == 3:
assert v[3] < len(qs), "2: unexpected value"
qs[v[3]].put(v[2])
else:
print ("2: error: ", v, " was an unexpected value.")
v = q_recv.get(True, 1)
except Empty:
print ("2: Timeout of maine receive queue")
for i in range(len(qs)):
qs[i].close();
qs[i] = None
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