Multiplex on queue.Queue?

Question

How can I go about \"selecting\" on multiple queue.Queue\'s simultaneously?

Golang has the desired feature with its channels:

select {
case i1 = <-c1:         


        

Answer 1

The pychan project duplicates Go channels in Python, including multiplexing. It implements the same algorithm as Go, so it meets all of your desired properties:

• Multiple producers and consumers can communicate through a Chan. When both a producer and consumer are ready, the pair of them will block
• Producers and consumers are serviced in the order they arrived (FIFO)
• An empty (full) queue will block consumers (producers).

Here's what your example would look like:

c1 = Chan(); c2 = Chan(); c3 = Chan()

try:
    chan, value = chanselect([c1, c3], [(c2, i2)])
    if chan == c1:
        print("Received %r from c1" % value)
    elif chan == c2:
        print("Sent %r to c2" % i2)
    else:  # c3
        print("Received %r from c3" % value)
except ChanClosed as ex:
    if ex.which == c3:
        print("c3 is closed")
    else:
        raise

(Full disclosure: I wrote this library)