Christian Grabowski Christian Grabowski - 11 months ago 61
C++ Question

Is there a performance cost using std::move vs using a pointer to the thread?

I imagine std::move() has a bit more of a performance cost in the context of something like:

std::thread thrd(&func, this);
someArrOfThreads[0] = std::move(thrd);


std::thread *thrd = new std::thread(&func, this);
someArrOfThreadPointers[0] = thrd;

Is this true? And if so, is it a matter of
changes the boundaries of memory of the thread or something else?

I realize there is the difference that in the first I am actually assigning a value of the array to the thread, and the other being the pointer to the thread, the thread stays in its address(es) in the second.

Answer Source

The only thing that std::move does is turn a lvalue into an rvalue reference. This then causes the rvalue reference version of tge assigment operator to be call. From a code generation point of view it is a noop.

The rvalue overload is likely to be more efficient since it is allowed to move class internal as opposed to performing a deep copy.