Multithreading

Multithreading is about employing user threads to perform parallel tasks in a concurrent environment. It's very rare to find a non-trivial program that has only a single thread; almost every program you'll encounter is multithreaded. Threads can only exist inside processes; we cannot have any thread without an owner process. Each process has at least one thread, which is usually called the main thread. A program that is using a single thread to perform all its tasks is called a single-threaded program. All threads within a process have access to the same memory regions, and this means that we won't have to come up with a complex scenario to share a piece of data, like we do in multi-processing.

Since threads are very similar to processes, they can use all the techniques that processes use to share or transfer a state. Therefore, all the techniques explained in the previous section can be employed by threads to access a shared state or transfer...