Asynchronous programming in Windows service, Is it relevant

Question

In windows service, we do not have any blocking UI thread, so is it relevant to use Asynchronous programming inside windows service ??

Answer 1

Async programming allows the efficient use of threads when they are executing blocking tasks. Blocking occurs in the ui but also when performing IO and therefore when communicating.

If your service does not perform heavy IO and does not use sockets and pipes, you won't have a benefit within the service; although I cannot image what such service could do.

Generally speaking, async programming produce also a benefit in the hosting system because it allows to globally use fewer resources to run your workload. However, you have to consider that async programming does not perform any resource sharing as said in other answers: your implementation will use your threads in a more efficient way (i.e. Task oriented), but you won't magically have more threads available.

Answer 2

The alternatives are to either block (i.e. do nothing until required data is available) or await (yield processing and then return automatically when the data is available).

In a situation when the program (a Windows service included) can do nothing further until the data arrives, there may seem little difference between the two, and as far as that program itself is concerned, this is true.

However, the program will be running in a thread allocated to it by the operating system (even if it is using only a single thread). Threads are not free resources and if a large number are in use, the OS will not hand out new ones until old ones terminate or become free. Thus other programs will be held up.

When a program blocks, it keeps hold of its thread, making it unavailable for use else where. When it awaits, the thread becomes available for others to use.

So using await will make the whole computer run more efficiently.

Answer 3

The two things aren't related.

Most Windows services don't have a gui thread as they don't have a GUI. Instead they'll have a main thread, and probably many other child threads that implement the service. Any of these threads may want to mak use of asynchronous programing techniques. For example, they may be reading or writing over a socket, a classic example of using an asychronous programming model.