c# - Why does ContinueWith execute if I do a delay inside a task -

i'm little confused continuewith in task parallel library seems do.

my understanding shouldn't called until task has been completed. if i'm in while true loop shouldn't getting called @ all.

        datetime t = datetime.now.addseconds(10);         task.factory.startnew(async () =>             {                 while (true)                 {                     if (t < datetime.now)  //after 10s throw                     {                          throw new exception(); //i expect run continuation here                     }                      console.writeline("looped");                     await task.delay(new timespan(0, 0, 1));                 }             }         ).continuewith(ct => console.writeline("continued with: {0}",ct.result.status)) ; 

i expect following code not run continuewith method until exception thrown isn't case. instead following output:

looped continued with: waitingforactivation looped looped looped looped looped looped looped looped looped 

why call continuewith when hit first delay?

you've created evil async void delegate.

it finishes (completing original task) synchronous part completes.
there no way observe asynchronous part of original delegate.

your original delegate returns asynchronous task representing async part of operation.
however, outer task completes synchronous part finishes, , never wait inner task finish.

instead, should call task.run(), accepts func<task>.
way, asynchronous portions of original delegate contribute original task.