鼠兔`从空队列中弹出`

问题描述

我在 kubernetes 集群中使用 pika 并使用队列中的消息,这会触发在新线程中启动一个函数。然而 RabbitMQ 似乎崩溃了,这些是迄今为止我发现的最好的日志:

2020-12-23 10:39:10,906] WARNING - WRITE indicated on fd=9,but writer callback is None; events=0b100 {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/selector_ioloop_adapter.py:393}
(repeats to a total of n=38 times)
2020-12-23 10:39:10,908] ERROR - _AsyncBaseTransport._produce() Failed,aborting connection: error=IndexError('pop from an empty deque'); sock=<socket.socket fd=9,family=AddressFamily.AF_INET,type=SocketKind.soCK_STREAM,proto=6,laddr=('192.168.100.200',44892),raddr=('192.168.101.201',5672)>; Caller's stack:                                                                                 
Traceback (most recent call last):                                                                                                 
File "/usr/local/lib/python3.9/site-packages/pika/adapters/utils/io_services_utils.py",line 1097,in _on_socket_writable        
    self._produce()                                                                                                                
File "/usr/local/lib/python3.9/site-packages/pika/adapters/utils/io_services_utils.py",line 822,in _produce                    
    chunk = self._tx_buffers.popleft()                                                                                             
IndexError: pop from an empty deque                                                                                                
{/usr/local/lib/python3.9/site-packages/pika/adapters/utils/io_services_utils.py:1103}                                            
Traceback (most recent call last):                                                                                                 
File "/usr/local/lib/python3.9/site-packages/pika/adapters/utils/io_services_utils.py",in _produce                    
    chunk = self._tx_buffers.popleft()                                                                                             
IndexError: pop from an empty deque                                                                                                
2020-12-23 10:39:10,908] INFO - _AsyncTransportBase._initate_abort(): Initiating abrupt asynchronous transport shutdown: state=1; error=IndexError('pop from an empty deque'); <socket.socket fd=9,5672)> {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/io_services_utils.py:904}                                                                                                               
2020-12-23 10:39:10,908] INFO - Deactivating transport: state=1; <socket.socket fd=9,5672)> {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/io_services_utils.py:869}
2020-12-23 10:39:10,909] ERROR - connection_lost: StreamLostError: ("Stream connection lost: IndexError('pop from an empty deque')",) {/usr/local/lib/python3.9/site-packages/pika/adapters/base_connection.py:428}                                                   
2020-12-23 10:39:10,909] INFO - AMQP stack terminated,Failed to connect,or aborted: opened=True,error-arg=StreamLostError: ("Stream connection lost: IndexError('pop from an empty deque')",); pending-error=None {/usr/local/lib/python3.9/site-packages/pika/connection.py:1996}
2020-12-23 10:39:10,909] INFO - Stack terminated due to StreamLostError: ("Stream connection lost: IndexError('pop from an empty deque')",) {/usr/local/lib/python3.9/site-packages/pika/connection.py:2065}                                                          
2020-12-23 10:39:10,909] INFO - Closing transport socket and unlinking: state=2; <socket.socket fd=9,5672)> {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/io_services_utils.py:882}      
2020-12-23 10:39:10,909] ERROR - Unexpected connection close detected: StreamLostError: ("Stream connection lost: IndexError('pop from an empty deque')",) {/usr/local/lib/python3.9/site-packages/pika/adapters/blocking_connection.py:520} 
2020-12-23 10:39:31,416] INFO - pika version 1.1.0 connecting to ('192.168.101.201',5672) {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/connection_workflow.py:179}                  
2020-12-23 10:39:31,417] INFO - Socket connected: <socket.socket fd=9,47142),5672)> {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/io_services_utils.py:345}                                                                                                         
2020-12-23 10:39:31,418] INFO - Streaming transport linked up: (<pika.adapters.utils.io_services_utils._AsyncPlaintextTransport object at 0x7f81b3099a60>,_StreamingProtocolShim: <SelectConnection PROTOCOL transport=<pika.adapters.utils.io_services_utils._AsyncPlaintextTransport object at 0x7f81b3099a60> params=<ConnectionParameters host=rabbitmq-0.rabbitmq.testing.svc.cluster.local port=5672 virtual_host=/ ssl=False>>). {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/connection_workflow.py:428}
2020-12-23 10:39:31,421] INFO - AMQPConnector - reporting success: <SelectConnection OPEN transport=<pika.adapters.utils.io_services_utils._AsyncPlaintextTransport object at 0x7f81b3099a60> params=<ConnectionParameters host=rabbitmq-0.rabbitmq.testing.svc.cluster.local port=5672 virtual_host=/ ssl=False>> {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/connection_workflow.py:293}
2020-12-23 10:39:31,421] INFO - AMQPConnectionWorkflow - reporting success: <SelectConnection OPEN transport=<pika.adapters.utils.io_services_utils._AsyncPlaintextTransport object at 0x7f81b3099a60> params=<ConnectionParameters host=rabbitmq-0.rabbitmq.testing.svc.cluster.local port=5672 virtual_host=/ ssl=False>> {/usr/local/lib/python3.9/site-packages/pika/adapters/utils/connection_workflow.py:725}                                                                                                                          
2020-12-23 10:39:31,421] INFO - Connection workflow succeeded: <SelectConnection OPEN transport=<pika.adapters.utils.io_services_utils._AsyncPlaintextTransport object at 0x7f81b3099a60> params=<ConnectionParameters host=rabbitmq-0.rabbitmq.testing.svc.cluster.local port=5672 virtual_host=/ ssl=False>> {/usr/local/lib/python3.9/site-packages/pika/adapters/blocking_connection.py:452} 
2020-12-23 10:39:31,422] INFO - Created channel=1 {/usr/local/lib/python3.9/site-packages/pika/adapters/blocking_connection.py:1247
}

我的消费者有以下定义:

def publish_message(channel,message):
    channel.basic_publish(exchange='',routing_key='my_queue',body=message)


def connect_to_mq():
    credentials = pika.PlainCredentials(rabbit_user,rabbit_password)
    parameters = pika.ConnectionParameters(rabbit_host,rabbit_port,'/',credentials)
    connection = pika.BlockingConnection(parameters=parameters)
    channel = connection.channel()
    channel.queue_declare(queue='my_queue')
    return connection,channel
    
    
def on_message(channel,method_frame,header_frame,body):
    message = body.decode('utf-8')
    if message == 'do_work':
        thread = threading.Thread(target=start_processing,args=(channel,))
        thread.start()
        publish_message(channel,'initiated thread')
    
    
def start_processing(channel):
    publish_message(channel,'starting...')
    time.sleep(240)
    publish_message(channel,'processing complete!')


def main():
    connection,channel = connect_to_mq()
    channel.basic_consume(queue='my_queue',auto_ack=True,on_message_callback=on_message)

    channel.start_consuming()

我在单独的线程中处理消息和工作负载的实现和策略是否有任何固有的错误导致这种情况发生?

解决方法

Pika 默认不是线程安全的。理想情况下,您应该为每个线程保留一个连接。

有一堆示例实现 here,我有一个线程安全的 rpc 示例 here,您也可以查看,但我建议使用他们的参考实现之一进行线程处理。

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