popen_read_multiple.py

"""
example

reading results from possibly blocking code running in sub processes.
"""

import execnet

NUM_PROCESSES = 5

channels = []
for i in range(NUM_PROCESSES):
    gw = execnet.makegateway()  # or use SSH or socket gateways
    channel = gw.remote_exec(
        """
        import time
        secs = channel.receive()
        time.sleep(secs)
        channel.send("waited %d secs" % secs)
    """
    )
    channels.append(channel)
    print("*** instantiated subprocess", gw)

mc = execnet.MultiChannel(channels)
queue = mc.make_receive_queue()

print("*** verifying that timeout on receiving results from blocked subprocesses works")
try:
    queue.get(timeout=1.0)
except Exception:
    pass

print("*** sending subprocesses some data to have them unblock")
mc.send_each(1)

print("*** receiving results asynchronously")
for i in range(NUM_PROCESSES):
    channel, result = queue.get(timeout=2.0)
    print("result", channel.gateway, result)