C++ STL with jemalloc

Question

How is it possible to use C++ STL containers with jemalloc (or any other malloc implementation)?

Is it as simple as include jemalloc/jemalloc.h? Or should I write an allocator for them?

Edit: The application I'm working on allocates and frees relatively small objects over its lifetime. I want the replace the default allocator, because benchmarks showed that the application doesn't scale beyond 2 cores. Profiling showed that it was waiting for memory allocation, that's what caused the scaling issues. As I understand, jemalloc will help with that.

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I'd like to see a solution, that's platform-neutral as the application has to work on both Linux and Windows. (Linking against a different implementation is easy under Linux, but it's very hard on Windows as far as I know.)

Answer 1

C++ allows you to replace operator new. If this replacement operator new calls je_malloc, then std::allocator will indirectly call je_malloc, and in turn all standard containers will.

This is by far the simplest approach. Writing a custom allocator requires writing an entire class. Replacing malloc may not be sufficient (there's no guarantee that the non-replaced operator new calls malloc), and it has the risks noted earlier by Adrian McCarthy