在 C# 中使用 azure 服务总线的指数退避

Question

I am trying to implement exponential backoff with azure service bus. Basically i have a catch block and if any error currently what i am doing is i am asking it to retry after every 1 second and i am awaiting that.

Goal: I want to use exponential delay. So basically after each retry i want exponentially increase the seconds and i dont want it to wait. Till then it can process other messages.

Current catch block looks like:

catch (Exception ex)
                {
                    _logger.Error(ex, $"Failed to process request {requestId}");
                    totalAttempts++;

                    if (totalAttempts == MaxAttempts)
                        return new Response { Error = ex.ToString() };
                    
                    await Task.Delay(TimeSpan.FromSeconds(1));
                }

I tried the below but it is not exponentially increasing the time. I am using this for the first time. while (true)

try
            {
                executemethod();
            }
catch (Exception ex)
                {
                    _logger.Error(ex, $"Failed to process request {requestId}");
                    totalAttempts++;

                    if (totalAttempts == MaxAttempts)
                        return new Response { Error = ex.ToString() };
                   queueClient.RetryPolicy = new RetryExponential(TimeSpan.FromSeconds(5), TimeSpan.FromSeconds(30), 10);
                    
                }

I am not very much sure if i am doing correct.

Goal: need to retry with a back-off strategy and make the processing thread available for other messages while waiting for the next retry.Consider exponential back-off with dead-lettering after reaching max delivery attempts.

Answer 1

Many Azure-oriented .NET libraries implement Retry internally. Service Bus client has it built-in as well. Check out Retry guidance for Azure services . As per documentation:

When using the built-in RetryExponential implementation, do not implement a fallback operation as the policy reacts to Server Busy exceptions and automatically switches to an appropriate retry mode.

Other from that, you shall set policy before you make a request and not in the process.

Answer 2

For retry policies, you can also use an external library like Polly .