RabbiMQ C# driver Causes System.AccessViolationException

Question

We have an ASP.Net WebAPI 2.0 application that publishes messages to our RabbitMQ Server. In 99% of the cases, all is well... but randomly the application terminates with a System.AccessViolationException for no apparent reason.

How can I prevent this failure? Could it be related to our recent upgrade to the 3.6.6 C# driver (it worked fine before the upgrade)?

Things I have already eliminated:

A new IModel is used for each publish (I know IModel is not thread safe)
A call is made to CreateConnection for each call as well (I know I could reuse the connection, but we do not currently). The connection is AutoClose = true;
The Channel is used in a using block... so it is disposed each time

Here is a sample stack trace of where it explodes:

Exception Details

System.AccessViolationException

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

at System.Net.UnsafeNclNativeMethods.SafeNetHandlesXPOrLater.GetAddrInfoW(String nodename, String servicename, AddressInfo& hints, SafeFreeAddrInfo& handle) at System.Net.Dns.TryGetAddrInfo(String name, AddressInfoHints flags, IPHostEntry& hostinfo) at System.Net.Dns.InternalGetHostByName(String hostName, Boolean includeIPv6) at System.Net.Dns.GetHostAddresses(String hostNameOrAddress) at RabbitMQ.Client.TcpClientAdapter.BeginConnect(String host, Int32 port, AsyncCallback requestCallback, Object state) at RabbitMQ.Client.Impl.SocketFrameHandler.Connect(ITcpClient socket, AmqpTcpEndpoint endpoint, Int32 timeout) at RabbitMQ.Client.Impl.SocketFrameHandler..ctor(AmqpTcpEndpoint endpoint, Func`2 socketFactory, Int32 connectionTimeout, Int32 readTimeout, Int32 writeTimeout) at RabbitMQ.Client.Framing.Impl.ProtocolBase.CreateFrameHandler(AmqpTcpEndpoint endpoint, Func'2 socketFactory, Int32 connectionTimeout, Int32 readTimeout, Int32 writeTimeout) at RabbitMQ.Client.ConnectionFactory.CreateConnection(IList'1 endpoints, String clientProvidedName)

And another

System.Net.UnsafeNclNativeMethods+SafeNetHandlesXPOrLater.GetAddrInfoW(System.String, System.String, System.Net.AddressInfo ByRef, System.Net.SafeFreeAddrInfo ByRef) System.Net.Dns.TryGetAddrInfo(System.String, System.Net.AddressInfoHints, System.Net.IPHostEntry ByRef) System.Net.Dns.InternalGetHostByName(System.String, Boolean) System.Net.Dns.GetHostAddresses(System.String) RabbitMQ.Client.TcpClientAdapter.BeginConnect(System.String, Int32, System.AsyncCallback, System.Object) RabbitMQ.Client.Impl.SocketFrameHandler.Connect(RabbitMQ.Client.ITcpClient, RabbitMQ.Client.AmqpTcpEndpoint, Int32) RabbitMQ.Client.Impl.SocketFrameHandler..ctor(RabbitMQ.Client.AmqpTcpEndpoint, System.Func'2, Int32, Int32, Int32) RabbitMQ.Client.Framing.Impl.ProtocolBase.CreateFrameHandler(RabbitMQ.Client.AmqpTcpEndpoint, System.Func'2, Int32, Int32, Int32) RabbitMQ.Client.ConnectionFactory.CreateConnection(System.Collections.Generic.IList'1, System.String)

Kelly Kelly · Accepted Answer · 2017-01-17T03:26:02

I'm not sure exactly why your error is occurring I would need to see some of your code for that, but I use RabbitMQ quite a bit and to publish I use a class like so:

(Changed some parts as they are not relevant for your situation such as encryption, compression etc. But this would be the basic format of it)

using System;
using System.Text;
using RabbitMQ.Client;
using RabbitMQ.Client.Framing;

namespace Messaging
{
    public class MessageSender : IDisposable
    {
        private const string EXCHANGE_NAME = "MY_EXCHANGE";

        private readonly ConnectionFactory factory;
        private readonly IConnection connection;
        private readonly IModel channel;

        public MessageSender(string address, string username, string password)
        {
            factory = new ConnectionFactory {UserName = username, Password = password, HostName = address};

            connection = factory.CreateConnection();
            channel = connection.CreateModel();

            channel.ExchangeDeclare(EXCHANGE_NAME, "topic");
        }

        public void Send(string payload, string topic)
        {
            var prop = new BasicProperties();
            var data = Encoding.ASCII.GetBytes(payload);

            channel.BasicPublish(EXCHANGE_NAME, topic.ToUpper(), prop, data);
        }

        public void Dispose()
        {
            try
            {
                channel.Dispose();
                connection.Dispose();
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }
        }
    }
}

The idea is to let you issue multiple calls or a single one and dispose of the class when you wish. Wrap it with a using statement and your set.

Never had a single problem with this in about 3-4 years of using it, so you might be able to contrast this vs your code to find the differences.

RabbiMQ C# driver Causes System.AccessViolationException

2 Answers