Question

I am reading conflicting opinions here. Am I right that although an asynchronous method call also gets handled by a thread pool invisible to the user, this is likely to save resources because the underlying operating system is able to suspend these threads whilst IO calls are pending ?

Answer 1

You are exactly right. The IO threads are not only suspended, they are retired when they become unneeded. But async IO is not a general solution for all problems and here is why:

• Async algorithms are hard to code. The async code is more complicated and error-prone than synchronous variant
• IO completion callbacks work in special IO threads and programmer has to keep those threads as free as much it is possible; otherwise the system will slow down significantly. So if you go to async IO be ready to implement Producer-Consumer pattern for actual data handling
• If you have a demand in less than 150 parallel connections and the application runs on a PC machine then synchronous implementation will be a low-hanging fruit delivering ease of programming and satisfactory performance at the same time