libglaswegian

Use GHC's Memory Allocator from C/C++. Yes, I'm serious. You can do this:

#include <iostream>
#include <vector>

#include <glaswegian++.h>

#define LEN 4096

int main()
{
    ghc_init();
    std::vector<double, GlaswegianAllocator<double>> xs;
    for(int i = 0; i < LEN; i++)
    {
        xs.emplace_back(i * i);
    }
    double s = 0;
    for(double i : xs)
    {
        s += i;
    }
    std::cout << s << std::endl;
    return 0;
}

This works by allocating pinned MutableByteArray#s, then sticking a StablePtr into a radix tree with the MutableByteArray#'s address as the key. This keeps the array alive on the heap until the caller frees the memory (which just deletes the StablePtr from the tree and does freeStablePtr).

A further optimization might be to call the RTS' C functions for doing allocations directly, but this library is shockingly competitive with other memory allocators. I'll add benchmarks soon.

This library is a fun toy I made for some silly benchmarks I wanted to run. It is probably only useful for getting your colleagues to shut up about how "garbage collectors are slow."