A new Thread should be created on ServiceMain?

Question

The MSDN says that:

"The ServiceMain function should create a global event, call the RegisterWaitForSingleObject function on this event, and exit. This will terminate the thread that is running the ServiceMain function, but will not terminate the service..."

So the question is: A new Thread should be created inside the ServiceMain function to execute the service code, or I can simple set the service to RUNNING state and uses the ServiceMain thread to run the service code? If the ServiceMain thread is used to run the service code the SCM will remain locked, even if the service state is set to RUNNING?

Answer 1

I do not think the way of implementing services described by that statement from MSDN is the only possible way. That would contradict MSDN service example at http://msdn.microsoft.com/en-us/library/windows/desktop/bb540476(v=vs.85).aspx . In the example the service waits for events in the same thread that called ServiceMain. This way is probably better for simple services that work just fine with a single thread.

If you choose to use RegisterWaitForSingleObject way you do not have to create threads explicitly. MSDN page for RegisterWaitForSingleObject says: "New wait threads are created automatically when required." You do have to open I/O channels you service is going to monitor and bind their handles to thread pool before exiting ServiceMain.