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zmq_queue.py
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zmq_queue.py
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# Based on the Paranoid Pirate queue by Daniel Lundin: http://zguide.zeromq.org/py:ppqueue
from collections import OrderedDict
import time
import sys
import zmq
import json
from zhelpers import socket_set_hwm
from datetime import datetime
from collections import deque
config = {
"LOGGING_SERVER_ADDR": "tcp://localhost:5500",
"LOG_INTERVAL": 1, # Log stats every 1 seconds
}
last_log_timestamp = time.time()
HEARTBEAT_LIVENESS = 10 # 3..5 is reasonable
HEARTBEAT_INTERVAL = 1.0 # Seconds
# Paranoid Pirate Protocol constants
PPP_READY = "\x01" # Signals worker is ready
PPP_HEARTBEAT = "\x02" # Signals worker heartbeat
alive_workers = {}
class Worker(object):
def __init__(self, address, hostname="???"):
self.address = address
self.hostname = hostname
self.expiry = time.time() + HEARTBEAT_INTERVAL * HEARTBEAT_LIVENESS
class WorkerQueue(object):
def __init__(self):
self.queue = OrderedDict()
def ready(self, worker):
""" Move worker from its old place to end of the queue """
self.queue.pop(worker.address, None)
self.queue[worker.address] = worker
# Update expiration date if exists, add to registry of alive workers if doesn't exist
if alive_workers.has_key(worker.address):
alive_workers[worker.address].expiry = worker.expiry
else:
alive_workers[worker.address] = worker
def keepalive(self, address):
if alive_workers.has_key(address):
alive_workers[address].expiry = time.time() + HEARTBEAT_INTERVAL * HEARTBEAT_LIVENESS
if self.queue.has_key(address):
self.queue[address].expiry = time.time() + HEARTBEAT_INTERVAL * HEARTBEAT_LIVENESS
def purge(self):
"""Look for & kill expired workers."""
t = time.time()
expired = []
for address,worker in alive_workers.iteritems():
if t > worker.expiry: # Worker expired
expired.append(address)
for address in expired:
print "W: Idle worker expired: %s" % address
self.queue.pop(address, None)
alive_workers.pop(address, None)
def next(self):
address, worker = self.queue.popitem(False)
return address
context = zmq.Context(1)
frontend = context.socket(zmq.ROUTER) # ROUTER
backend = context.socket(zmq.ROUTER) # ROUTER
info_sock = context.socket(zmq.REP)
socket_set_hwm(frontend, 5)
socket_set_hwm(backend, 5)
frontend.bind("tcp://*:5559") # For clients
backend.bind("tcp://*:5560") # For workers
info_sock.bind("tcp://*:5411") # for debugging internal state info
poll_workers = zmq.Poller()
poll_workers.register(backend, zmq.POLLIN)
poll_both = zmq.Poller()
poll_both.register(frontend, zmq.POLLIN)
poll_both.register(backend, zmq.POLLIN)
poll_both.register(info_sock, zmq.POLLIN)
workers = WorkerQueue()
heartbeat_at = time.time() + HEARTBEAT_INTERVAL
queue_length = {}
requests = deque()
def log_stats():
global last_log_timestamp
dT = time.time() - last_log_timestamp
if dT < config["LOG_INTERVAL"]:
return
last_log_timestamp = time.time()
logger = context.socket(zmq.REQ)
logger.connect(config["LOGGING_SERVER_ADDR"]) # For logging system
zmq_poll = zmq.Poller()
zmq_poll.register(logger, zmq.POLLIN)
message = ["WORKER_STATS", "{}".format(len(alive_workers)), "{}".format(len(workers.queue)), "{}".format(len(requests))]
logger.send_multipart(message)
try:
socks = dict(zmq_poll.poll(100))
if socks.get(logger) == zmq.POLLIN:
response = logger.recv()
if not response:
return False
else:
return True
else:
return False
except Exception as z:
print str(z)
return False
print "[{}] Entering main run loop...".format(datetime.now())
while True:
poller = poll_both
socks = dict(poller.poll(100))
# Handle requests for info
if socks.get(info_sock) == zmq.POLLIN:
frames = info_sock.recv_multipart()
def get_char(w):
id = bytearray(w)
return chr(id[len(id)-1])
list_workers = [{"id": get_char(w), "host": alive_workers[w].hostname} for w in alive_workers]
info_sock.send(json.dumps(list_workers, sort_keys=True, indent=4, separators=(',', ': ')))
# Handle worker activity on backend
if socks.get(backend) == zmq.POLLIN:
# Use worker address for LRU routing
frames = backend.recv_multipart()
if not frames:
break
address = frames[0]
msg = frames[1:]
# Validate control message, or return reply to client
if len(msg) == 1:
if msg[0] not in (PPP_READY, PPP_HEARTBEAT):
print "[{}] E: Invalid message from worker: {}".format(datetime.now(), msg)
elif msg[0] == PPP_READY:
print "[{}] Worker {} is now online!".format(datetime.now(), address)
workers.ready(Worker(address))
elif msg[0] == PPP_HEARTBEAT:
#print "[{}] Worker {} heartbeat".format(datetime.now(), address)
if not alive_workers.has_key(address):
workers.ready(Worker(address))
else:
workers.keepalive(address)
elif msg[0] == PPP_READY:
hostname = msg[1]
print "[{}] Worker {} is now online! (Host: {})".format(datetime.now(), address, hostname)
workers.ready(Worker(address, hostname))
elif msg[0] == PPP_HEARTBEAT:
hostname = msg[1]
if not alive_workers.has_key(address):
workers.ready(Worker(address, hostname))
else:
workers.keepalive(address)
else:
print "[{}] Received response from worker ID {}".format(datetime.now(), address)
frontend.send_multipart(msg)
print msg[2]
print "From worker: {}".format("-".join([str(ord(c)) for c in frames[0]]))
workers.ready(Worker(address))
# Send heartbeats to idle workers if it's time
if time.time() >= heartbeat_at:
#print "Sending heartbeat to workers..."
for worker in alive_workers:
msg = [worker, PPP_HEARTBEAT]
backend.send_multipart(msg)
heartbeat_at = time.time() + HEARTBEAT_INTERVAL
# Handle client request on the frontend
if socks.get(frontend) == zmq.POLLIN:
frames = frontend.recv_multipart()
if not frames:
break
if len(requests) >= len(alive_workers):
# Return an error that the queue is full
response = [frames[0], b'', "The queue is full!"]
frontend.send_multipart(response)
print "[{}] Queue is full! Dropping request.".format(datetime.now())
else:
requests.appendleft(frames)
print("[{}] Queue is {} request long. {}/{} workers ready.".format(datetime.now(), len(requests), len(workers.queue), len(alive_workers)))
if(len(requests) > 0):
print "[{}] Processing queue... {} workers available".format(datetime.now(), len(workers.queue))
while len(workers.queue) > 0 and len(requests) > 0:
frames = requests.popleft()
who_gets_this_one = workers.next()
frames.insert(0, who_gets_this_one)
print "[{}] Passing message to worker ID {} ({} available)".format(datetime.now(), who_gets_this_one, len(workers.queue))
backend.send_multipart(frames)
if len(workers.queue) == 0:
print "[{}] No more workers available! Adding to the queue...".format(datetime.now())
break
workers.purge()
log_stats()
sys.stdout.flush()