I'm writing some python code using pika 0.9.13 to connect to RabbitMQ. I'm creating lots of child processes (potentially 1000s) and want each process to be able to send to RabbitMQ. Reading around, it seems the best way is to create a single connection and then create channels within that connection.
Can anyone advise how best this should be done ? Typically the code would look like :-
from multiprocessing import Process
def f(connection):
# pass the pika connection somehow ...
# create the channel ...
channel = connection.channel()
# .... rest of process code
if __name__ == '__main__':
#
# pika code here to establish the MQ connection ...
# connection = ....
p = Process(target=f, args=(connection,))
p.start()
What type of adapter should I use (BlockingConnection ?) ...
Thanks in advance !
Related
Unable to timeout a grpc connection from server side. It is possible that client establishes a connection but kept on hold/sleep which is resulting in grpc server connection to hang. Is there a way at server side to disconnect the connection after a certain time or set the timeout?
We tried disconnecting the connection from client side but unable to do so from server side. In this link Problem with gRPC setup. Getting an intermittent RPC unavailable error, Angad says that it is possible but unable to define those parameters in python.
My code snippet:
def serve():
server = grpc.server(thread_pool=futures.ThreadPoolExecutor(max_workers=2), maximum_concurrent_rpcs=None, options=(('grpc.so_reuseport', 1),('grpc.GRPC_ARG_KEEPALIVE_TIME_MS', 1000)))
stt_pb2_grpc.add_ListenerServicer_to_server(Listener(), server)
server.add_insecure_port("localhost:50051")
print("Server starting in port "+str(50051))
server.start()
try:
while True:
time.sleep(60 * 60 * 24)
except KeyboardInterrupt:
server.stop(0)
if __name__ == '__main__':
serve()
I expect the connection should be timed out from grpc server side too in python.
In short, you may find context.abort(...) useful, see API reference. Timeout a server handler is not supported by the underlying C-Core API of gRPC Python. So, you have to implement your own timeout mechanism in Python.
You can try out some solution from other StackOverflow questions.
Or use a simple-but-big-overhead extra threads to abort the connection after certain length of time. It might look like this:
_DEFAULT_TIME_LIMIT_S = 5
class FooServer(FooServicer):
def RPCWithTimeLimit(self, request, context):
rpc_ended = threading.Condition()
work_finished = threading.Event()
def wrapper(...):
YOUR_ACTUAL_WORK(...)
work_finished.set()
rpc_ended.notify_all()
def timer():
time.sleep(_DEFAULT_TIME_LIMIT_S)
rpc_ended.notify_all()
work_thread = threading.Thread(target=wrapper, ...)
work_thread.daemon = True
work_thread.start()
timer_thread = threading.Thread(target=timer)
timer_thread.daemon = True
timer_thread.start()
rpc_ended.wait()
if work_finished.is_set():
return NORMAL_RESPONSE
else:
context.abort(grpc.StatusCode.DEADLINE_EXCEEDED, 'RPC Time Out!')
I am using Celery with Rabbitmq broker on Server A. Some tasks require interaction with another server say, Server B and I am using Rabbitmq queues for this interaction.
Queue 1 - Server A (Producer), Server B (Consumer)
Queue 2 - Server B (Producer), Server A (Consumer)
My celery is unexpectedly hanging and I have found the reason to be incorrect implementation of Server A consumer code.
channel.start_consuming() keeps polling Rabbitmq as expected however putting this in a celery task creates multiple pollers which don't expire. I can add expiry but the time completion for the data being sent to Server B cannot be guaranteed. The code pasted below is one method I used to tackle the issue but I am not convinced this is best solution.
I wish to know what I am doing wrong and what is the right way to implement this because I have failed searching for articles on the web. Any tips, insights and even links to articles would be extremely helpful.
Finally, my code -
#celery.task
def task_a(data):
do_some_processing
# Create only 1 Rabbitmq consumer instance to avoid celery hangups
task_d.delay()
#celery.task
def task_b(data):
do_some_processing
if data is not None:
task_c.delay()
#celery.task
def task_c():
data = some_data
data = json.dumps(data)
conn_params = pika.ConnectionParameters(host=RABBITMQ_HOST)
connection = pika.BlockingConnection(conn_params)
channel = connection.channel()
channel.queue_declare(queue=QUEUE_1)
channel.basic_publish(exchange='',
routing_key=QUEUE_1,
body=data)
channel.close()
#celery.task
def task_d():
def queue_helper(ch, method, properties, body):
'''
Callback from queue.
'''
data = json.loads(body)
task_b.delay(data)
conn_params = pika.ConnectionParameters(host=RABBITMQ_HOST)
connection = pika.BlockingConnection(conn_params)
channel = connection.channel()
channel.queue_declare(queue=QUEUE_2)
channel.basic_consume(queue_helper,
queue=QUEUE_2,
no_ack=True)
channel.start_consuming()
channel.close()
How can I programmatically, using Python code, list current queues created on a RabbitMQ broker and the number of workers connected to them? It would be the equivalent to:
rabbitmqctl list_queues name consumers
I do it this way and display all the queues and their details (messages ready, unacknowledged etc.) on a web page -
import kombu
conn = kombu.Connection(broker_url)# example 'amqp://guest:guest#localhost:5672/'
conn.connect()
client = conn.get_manager()
queues = client.get_queues('/')#assuming vhost as '/'
You will need kombu to be installed and queues will be a dictionary with keys representing the queue names.
I think I got this when digging through the code of celery flower (The tool used for monitoring celery).
Update: As pointed out by #zaq178miami, you will also need the management plugin that has the http API. I had forgotten that I had enabled than in rabbitmq.
This way did it for me:
def get_queue_info(queue_name):
with celery.broker_connection() as conn:
with conn.channel() as channel:
return channel.queue_declare(queue_name, passive=True)
This will return a namedtuple with the name, number of messages waiting and consumers of that queue.
ksrini answer is correct too and can be used when you require more information about a queue.
Thanks to Ask Solem who gave me the hint.
As a rabbitmq client you can use pika. However it doesn't have option for list_queues. The easiest solution would be calling rabbitmqctl command from python using subprocess:
import subprocess
command = "/usr/local/sbin/rabbitmqctl list_queues name consumers"
process = subprocess.Popen(command.split(), stdout=subprocess.PIPE)
print process.communicate()
I would use simply this:
Just replace the user(default= guest), passwd(default= guest) and port with your values.
import requests
import json
def call_rabbitmq_api(host, port, user, passwd):
url = 'https://%s:%s/api/queues' % (host, port)
r = requests.get(url, auth=(user,passwd),verify=False)
return r
def get_queue_name(json_list):
res = []
for json in json_list:
res.append(json["name"])
return res
if __name__ == '__main__':
host = 'rabbitmq_host'
port = 55672
user = 'guest'
passwd = 'guest'
res = call_rabbitmq_api(host, port, user, passwd)
print ("--- dump json ---")
print (json.dumps(res.json(), indent=4))
print ("--- get queue name ---")
q_name = get_queue_name(res.json())
print (q_name)
Referred from here: https://gist.github.com/hiroakis/5088513#file-example_rabbitmq_api-py-L2
I am trying to implement an IRC Bot on a local server. The bot that I am using is identical to the one found at Eric Florenzano's Blog. This is the simplified code (which should run)
import sys
import re
from twisted.internet import reactor
from twisted.words.protocols import irc
from twisted.internet import protocol
class MomBot(irc.IRCClient):
def _get_nickname(self):
return self.factory.nickname
nickname = property(_get_nickname)
def signedOn(self):
print "attempting to sign on"
self.join(self.factory.channel)
print "Signed on as %s." % (self.nickname,)
def joined(self, channel):
print "attempting to join"
print "Joined %s." % (channel,)
def privmsg(self, user, channel, msg):
if not user:
return
if self.nickname in msg:
msg = re.compile(self.nickname + "[:,]* ?", re.I).sub('', msg)
prefix = "%s: " % (user.split('!', 1)[0], )
else:
prefix = ''
self.msg(self.factory.channel, prefix + "hello there")
class MomBotFactory(protocol.ClientFactory):
protocol = MomBot
def __init__(self, channel, nickname='YourMomDotCom', chain_length=3,
chattiness=1.0, max_words=10000):
self.channel = channel
self.nickname = nickname
self.chain_length = chain_length
self.chattiness = chattiness
self.max_words = max_words
def startedConnecting(self, connector):
print "started connecting on {0}:{1}"
.format(str(connector.host),str(connector.port))
def clientConnectionLost(self, connector, reason):
print "Lost connection (%s), reconnecting." % (reason,)
connector.connect()
def clientConnectionFailed(self, connector, reason):
print "Could not connect: %s" % (reason,)
if __name__ == "__main__":
chan = sys.argv[1]
reactor.connectTCP("localhost", 6667, MomBotFactory('#' + chan,
'YourMomDotCom', 2, chattiness=0.05))
reactor.run()
I added the startedConnection method in the client factory, which it is reaching and printing out the proper address:host. It then disconnects and enters the clientConnectionLost and prints the error:
Lost connection ([Failure instance: Traceback (failure with no frames):
<class 'twisted.internet.error.ConnectionDone'>: Connection was closed cleanly.
]), reconnecting.
If working properly it should log into the appropriate channel, specified as the first arg in the command (e.g. python module2.py botwar. would be channel #botwar.). It should respond with "hello there" if any one in the channel sends anything.
I have NGIRC running on the server, and it works if I connect from mIRC or any other IRC client.
I am unable to find a resolution as to why it is continually disconnecting. Any help on why would be greatly appreciated. Thank you!
One thing you may want to do is make sure you will see any error output produced by the server when your bot connects to it. My hunch is that the problem has something to do with authentication, or perhaps an unexpected difference in how ngirc handles one of the login/authentication commands used by IRCClient.
One approach that almost always applies is to capture a traffic log. Use a tool like tcpdump or wireshark.
Another approach you can try is to enable logging inside the Twisted application itself. Use twisted.protocols.policies.TrafficLoggingFactory for this:
from twisted.protocols.policies import TrafficLoggingFactory
appFactory = MomBotFactory(...)
logFactory = TrafficLoggingFactory(appFactory, "irc-")
reactor.connectTCP(..., logFactory)
This will log output to files starting with "irc-" (a different file for each connection).
You can also hook directly into your protocol implementation, at any one of several levels. For example, to display any bytes received at all:
class MomBot(irc.IRCClient):
def dataReceived(self, bytes):
print "Got", repr(bytes)
# Make sure to up-call - otherwise all of the IRC logic is disabled!
return irc.IRCClient.dataReceived(self, bytes)
With one of those approaches in place, hopefully you'll see something like:
:irc.example.net 451 * :Connection not registered
which I think means... you need to authenticate? Even if you see something else, hopefully this will help you narrow in more closely on the precise cause of the connection being closed.
Also, you can use tcpdump or wireshark to capture the traffic log between ngirc and one of the working IRC clients (eg mIRC) and then compare the two logs. Whatever different commands mIRC is sending should make it clear what changes you need to make to your bot.
I'm implementing a Twisted-based Heartbeat Client/Server combo, based on this example. It is my first Twisted project.
Basically it consists of a UDP Listener (Receiver), who calls a listener method (DetectorService.update) on receiving packages. The DetectorService always holds a list of currently active/inactive clients (I extended the example a lot, but the core is still the same), making it possible to react on clients which seem disconnected for a specified timeout.
This is the source taken from the site:
UDP_PORT = 43278; CHECK_PERIOD = 20; CHECK_TIMEOUT = 15
import time
from twisted.application import internet, service
from twisted.internet import protocol
from twisted.python import log
class Receiver(protocol.DatagramProtocol):
"""Receive UDP packets and log them in the clients dictionary"""
def datagramReceived(self, data, (ip, port)):
if data == 'PyHB':
self.callback(ip)
class DetectorService(internet.TimerService):
"""Detect clients not sending heartbeats for too long"""
def __init__(self):
internet.TimerService.__init__(self, CHECK_PERIOD, self.detect)
self.beats = {}
def update(self, ip):
self.beats[ip] = time.time()
def detect(self):
"""Log a list of clients with heartbeat older than CHECK_TIMEOUT"""
limit = time.time() - CHECK_TIMEOUT
silent = [ip for (ip, ipTime) in self.beats.items() if ipTime < limit]
log.msg('Silent clients: %s' % silent)
application = service.Application('Heartbeat')
# define and link the silent clients' detector service
detectorSvc = DetectorService()
detectorSvc.setServiceParent(application)
# create an instance of the Receiver protocol, and give it the callback
receiver = Receiver()
receiver.callback = detectorSvc.update
# define and link the UDP server service, passing the receiver in
udpServer = internet.UDPServer(UDP_PORT, receiver)
udpServer.setServiceParent(application)
# each service is started automatically by Twisted at launch time
log.msg('Asynchronous heartbeat server listening on port %d\n'
'press Ctrl-C to stop\n' % UDP_PORT)
This heartbeat server runs as a daemon in background.
Now my Problem:
I need to be able to run a script "externally" to print the number of offline/online clients on the console, which the Receiver gathers during his lifetime (self.beats). Like this:
$ pyhb showactiveclients
3 clients online
$ pyhb showofflineclients
1 client offline
So I need to add some kind of additional server (Socket, Tcp, RPC - it doesn't matter. the main point is that i'm able to build a client-script with the above behavior) to my DetectorService, which allows to connect to it from outside. It should just give a response to a request.
This server needs to have access to the internal variables of the running detectorservice instance, so my guess is that I have to extend the DetectorService with some kind of additionalservice.
After some hours of trying to combine the detectorservice with several other services, I still don't have an idea what's the best way to realize that behavior. So I hope that somebody can give me at least the essential hint how to start to solve this problem.
Thanks in advance!!!
I think you already have the general idea of the solution here, since you already applied it to an interaction between Receiver and DetectorService. The idea is for your objects to have references to other objects which let them do what they need to do.
So, consider a web service that responds to requests with a result based on the beats data:
from twisted.web.resource import Resource
class BeatsResource(Resource):
# It has no children, let it respond to the / URL for brevity.
isLeaf = True
def __init__(self, detector):
Resource.__init__(self)
# This is the idea - BeatsResource has a reference to the detector,
# which has the data needed to compute responses.
self._detector = detector
def render_GET(self, request):
limit = time.time() - CHECK_TIMEOUT
# Here, use that data.
beats = self._detector.beats
silent = [ip for (ip, ipTime) in beats.items() if ipTime < limit]
request.setHeader('content-type', 'text/plain')
return "%d silent clients" % (len(silent),)
# Integrate this into the existing application
application = service.Application('Heartbeat')
detectorSvc = DetectorService()
detectorSvc.setServiceParent(application)
.
.
.
from twisted.web.server import Site
from twisted.application.internet import TCPServer
# The other half of the idea - make sure to give the resource that reference
# it needs.
root = BeatsResource(detectorSvc)
TCPServer(8080, Site(root)).setServiceParent(application)