Is dynamic memory allocation in C++11 thread-safe?

Question

Is allocation and deallocation of dynamic memory in C++11 thread-safe? In other words: Can threads use new and delete as freely as single-threaded code?

Answer 1

Yes, dynamic allocation by ::operator new and deallocation by ::operator delete is thread-safe. An implementation is however permitted to have a global lock (e.g. on malloc called by new) which would serialize the allocation. If your program redefines ::operator new & ::operator delete it should ensure that they are thread-safe.

Regarding delete you should not delete the same pointer twice (e.g. in two different threads).