Parallel / Concurrent / Async Programming in C# using Tasks

Introduction

This one is a direct result of my work. Recently I was asked to come up with a notification / reminder service to send emails when something remains pending since a week. The initial code looked & worked great locally but once I deployed it to DEV it started running too slow. Obviously, there were 1000's of records on DEV & the service was chocking at the exact code line where I was sending the emails.

Solution

The solution was to use parallel programming techniques. Tasks is what I ended up using. You can follow these steps to add Tasks in your own applications:

1. Add using System.Threading.Tasks to your code file

2. Create a Task List to hold each task:

   
   
         List<Task> sendEmailTaskList =     new  List<Task>();
   

3. Add the Task to this Task List:

   
   
         sendEmailTaskList.Add(Task.Factory.StartNew(() =>  
         {  
                       Email.Send(      /*some params*/      );      
         }));  
   

4. Wait for all tasks to complete:

   
   
         Task.WaitAll(sendEmailTaskList.ToArray());  
   

Conclusion

By re-factoring the older, slow synchronous code to async / parallel code using Tasks, I could easily see much much better performance on DEV - I think it was at least 300% faster, of course this number really would depend on the actual code / work.

See Also

Please see this related code sample which illustrates using async, await keywords.