As Far as I know,
In computer science, a thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system. The implementation of threads and processes differs between operating systems, but in most cases a thread is a component of a process. Multiple threads can exist within one process, executing concurrently and sharing resources such as memory, while different processes do not share these resources. In particular, the threads of a process share its executable code and the values of its variables at any given time.[1]
When I decided to write a multi thread program in c++, i faced with many choices like boost thread, posix thread and std thread.
A simple search on internet shows a performance measurement taken by boost.org website here.
My question is a bit more basic and performance related as well.
Basically, Why do they differ in performance ? Why, for example thread type A, is faster than the others? The are written by most professional programmers, are ran by powerful OSs ,yet they offer different performance.
What makes them faster or slower?
The Boost documentation refers to the Fiber library, which are not actually threads. Creating what the library calls a fiber (essentially a user-space thread or coroutine, sometimes also referred to as green threads) does not create a separate schedulable entity on the kernel side, so it can be much more efficient at creation time. Other things could be less efficient because I/O operations necessarily become much more involved under this model (because a fiber doing I/O should not block the operating system thread it runs on if other fibers could do work there).
Note that some of the coroutine implementations out there are well out of the conceptual limits of the de-facto GNU/Linux ABI and other POSIX-like operating systems, so they should be considered ugly hacks at best.