问题
I tried to send message and receive message using RabbitMQ. I dont have computer science background, the terms I used could not be very accurate.
I try to copy the tutorial file: When submitting my html form, my python script (cgi) the message is submitting to the queue
connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='task_queue', durable=True)
message = PN
channel.basic_publish(exchange='',
routing_key='task_queue',
body=message,
properties=pika.BasicProperties(
delivery_mode = 2, # make message persistent
))
connection.close()
my receiver is running :
connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='task_queue', durable=True)
print(' [*] Waiting for messages. To exit press CTRL+C')
def callback(ch, method, properties, body):
print(" [x] Received Project %r" % body)
#ch.basic_ack(delivery_tag = method.delivery_tag)
if not (os.path.isfile(js_path)):
print (' [*] ERROR files missing ')
#ch.basic_ack(delivery_tag = method.delivery_tag)
return
p= subprocess.Popen(run a subprocess here)
p.wait()
print (' [*] Temporary Files removed')
print(" [*] Waiting for messages. To exit press CTRL+C")
channel.basic_qos(prefetch_count=1)
channel.basic_consume(callback,queue='task_queue',no_ack=True)
channel.start_consuming()
It manages most of the time but randomly crash with the following error:
Traceback (most recent call last): File "Receive5.py", line 139, in channel.start_consuming() File "C:\Python27\lib\site-packages\pika\adapters\blocking_connection.py", line 1681, in start_consuming self.connection.process_data_events(time_limit=None) File "C:\Python27\lib\site-packages\pika\adapters\blocking_connection.py", line 647, in process_data_events self._flush_output(common_terminator) File "C:\Python27\lib\site-packages\pika\adapters\blocking_connection.py", line 426, in _flush_output raise exceptions.ConnectionClosed() pika.exceptions.ConnectionClosed
回答1:
This is because you are keeping the main thread waiting, and because of this pika cannot handle incoming messages; in this case it cannot respond to the heartbeat until the subprocess is done. This causes RabbitMQ to think that the client is dead and forces a disconnection.
If you want this to work with heartbeats (which is recommend) you need to periodically call connection.process_data_events. This can be done by adding a loop that checks if the thread is done, and every 30s or so call process_data_events until the thread is done.
回答2:
Look add this https://github.com/mosquito/aio-pika
It's an asynchio wrapper and if u understand the concept behind asynchron very easy to use :)
回答3:
it seems that it is not connecting to RabbitMQ at 127.0.0.1:5672 -- are you sure RabbitMQ is running and listening on 127.0.0.1:5672?
for linux (debian) users
You can check if RabbitMQ is installed by typing this command.
sudo service rabbitmq-server status
If you get back a response, that means it it installed. Check if it is running or not?
to start rabbitMQ serve type
sudo service rabbitmq-server start
to restart rabbitMq use this command
sudo service rabbitmq-server restart
No response means that you don't have Rabbitmq installed. install it by typing the following commands.
sudo apt-get update
sudo apt-get -y upgrade
sudo apt-get install rabbitmq-server
And then start the server by typing the start command above.
来源：https://stackoverflow.com/questions/37321089/rabbitmq-pika-exceptions-connectionclosed