C#: Thread-safe events

Question

Is the implementation below thread-safe? If not what am I missing? Should I have the volatile keywords somewhere? Or a lock somewhere in the OnProcessingC

Answer 1

There is no need for the private ProcessCompleted member to be an event - it could just be a field: private EventHandler ProcessCompleted; - inside the class it always goes straight to the field, so the event stuff is lost anyway.

The approach you've shown with an explicit lock object isn't much more thread-safe than just having a field-like event (i.e. public event EventHandler ProcessCompleted; - the only difference is that you aren't locking "this" (which is a good thing - you should ideally avoid locking on this).. The "handler variable" approach is the right one, but there are still side-effects you should be aware of.