As I wrote in the title, I would like to know if c++ stantard threads are managed in user or kernel space.
Thank you.
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As I wrote in the title, I would like to know if c++ stantard threads are managed in user or kernel space.
Thank you.
As happens almost always, the standard doesn’t mandate any particular implementation, it just requires that the exhibited behavior conforms to its rules.
Thus, the particular implementation is free to choose; on the other hand, probably many implementations will be based on boost.thread (on which the
std::threadproposal is based), so we can look at it to have an idea.This library uses pthreads on POSIX and Windows threads on Win32. Win32 threads are definitely kernel threads, but pthreads on their own are just yet another interface, which could be implemented both in user space and in kernel space (although almost any recent UNIX kernel provides facilities to implement them in kernel space).
So:
std::threadcan be anything, although, on “mainstream” PC operating systems/implementations, it’s very likely that you’ll get kernel threads. If for some reason you need to know more, check your compiler’s documentation.