[CAMEL-11996] RabbitConsumer could hang when RabbitMQ connection is lost and autoAck=false.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.18.0, 2.19.0, 2.20.0
• Fix Version/s: 2.19.5, 2.20.3, 2.21.0
• Component/s: camel-rabbitmq
• Estimated Complexity: Unknown
• Assignee: Claus Ibsen
• Reporter: Joel Mongård
• Created: 07/Nov/17 15:33
• Updated: 02/Feb/18 08:53
• Resolved: 02/Feb/18 08:53

Description

When the connection is lost to a RabbitMQ server and later restored there is the possibility that the RabbitConsumer hangs. The only way around this that I found is to restart my application.

I have experienced this problem in my testing environment running camel 2.18.3 where my RabbitMQ installation is not stable causing every consumer thread to hang on lock.acquire() .

The problem has been introduced in version 2.18.0 commit 7ee0977c9f5c327a95122f5b80202dc5dd872e40
A possible fix could be to include the statement if (!channel.isOpen()) return; in the try-finally block below it.

JUnit test

package org.apache.camel.component.rabbitmq;

import org.junit.Test;
import org.mockito.Mockito;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;

public class RabbitConsumerTest {
  private RabbitMQConsumer consumer = Mockito.mock(RabbitMQConsumer.class);
  private RabbitMQEndpoint endpoint = Mockito.mock(RabbitMQEndpoint.class);
  private Connection conn = Mockito.mock(Connection.class);
  private Channel channel = Mockito.mock(Channel.class);
     
  @Test(timeout=5000)
  public void testHandleDelivery_ShouldNotHangForeverIfChanelWasClosed() throws Exception {  
    Mockito.when(consumer.getEndpoint()).thenReturn(endpoint);  
    Mockito.when(consumer.getConnection()).thenReturn(conn);
    Mockito.when(conn.createChannel()).thenReturn(channel);
    Mockito.when(channel.isOpen()).thenReturn(false).thenReturn(true);
    
    RabbitConsumer rabbitConsumer = new RabbitConsumer(consumer);
    
    rabbitConsumer.handleDelivery(null, null, null, null);
    rabbitConsumer.handleDelivery(null, null, null, null);
    rabbitConsumer.stop();
  }
}

Issue Links

• relates to: CAMEL-11480 camel-rabbitmq - autorecovery creates additional channels