Try Catch outside of: await Task.Run(()

Question

Does try catch outside of: await Task.Run(() => make sense or just use them only inside of await?

private async void Test()
{
     try
     {
         await Task.Run(() =>
         {
             try
             {
                  DoingSomething();
             }
             catch (Exception ex)
             {
                  log.Error(ex.Message);
             }
         });
      }
      catch (Exception ex)
      {
          log.Error(ex.Message);
      }
}

Answer 1

If you handle Exception inside the delegate (in your case just for logging purpose), await will not raise an exception in normal circumstances. This should be fine.

private async Task Test()
{
         await Task.Run(() =>
         {
             try
             {
                  DoingSomething();
             }
             catch (Exception ex)
             {
                  log.Error(ex.Message);
             }
         });

}

However, since you are awaiting the Task, most probably, there will be some DoSomethingElse in the Test method, which might be affected by the outcome of the Task - in which case it also makes sense to have a try/catch around await.

private async Task Test()
{
     try
     {
         await Task.Run(() =>
         {
             try
             {
                  DoingSomething();
             }
             catch (SomeSpecialException spex)
             {
                  // it is OK to have this exception
                  log.Error(ex.Message);
             }
         });

         DoSomethingElse(); // does not run when unexpected exception occurs.
      }
      catch (Exception ex)
      {
          // Here we are also running on captured SynchronizationContext
          // So, can update UI to show error ....
      }
}