Async programming

Guidelines for asynchronous programming

The way our solution is built there is a large need for asynchrous functionality. It is important for the development teams to be aware of best practices as well as which antipatterns to avoid.

Best Practices

Async Antipatterns

Keep an eye out for anti-patterns and help the team to maintain a high quality in our code base.

Blocking on tasks with .Result

When an asynchronous call is needed in a synchronous method, the implementation below is quite common. This use of .Result ties up the thread that could be doing other useful work, but even more serious it might cause a deadlock.

Instead of implementations like this:

 public Party GetCurrentParty()
 {
     UserContext userContext = _userHelper.GetUserContext(HttpContext).Result;
     int userId = userContext.UserId;
     string cookieValue = Request.Cookies[_settings.GetAltinnPartyCookieName];
     int.TryParse(cookieValue, out int partyId);
     (...)
 }

Try using this:

 public async Party GetCurrentParty()
 {
    UserContext userContext = await _userHelper.GetUserContext(HttpContext);
    int userId = userContext.UserId;
    string cookieValue = Request.Cookies[_settings.GetAltinnPartyCookieName];
    int.TryParse(cookieValue, out int partyId);
    (...)
 }

Whenever in a method that needs to call an asynchronous method, make the method itself asynchronous.