On 22/06/15 01:39, Antoine Pitrou wrote:
Or perhaps the fact that those superiors APIs are a PITA.
Not all of them, no. HeapAlloc is a good example. Very easy to use, and the "one heap per thread" design often gives excellent performance compared to a single global heap. But on Linux we only have malloc et al., allocating from the global heap. How many Linux programmers have even considered using multiple heaps in combination with multi-threading? I can assure you it is not common. A good idea is to look at the Python C API. We have PyMem_Malloc, but nothing that compares to Windows' HeapAlloc. Not only does HeapAlloc remove the contention for the global heap, it can also serialize. Instead of serializing an object by traversing all references in the object tree, we just serialize the heap from which it was allocated. And as for garbage collection, why not deallocate the whole heap in one blow? Is the any reason to pair each malloc with free if one could just zap the whole heap? That is what HeapDestroy does. On Linux we would typically homebrew a memory pool to achieve the same thing. But a memory pool needs to traverse a chain of pointers and call free() multiple times, each time with contention for the spinlock protecting the global heap. And when allocating from a memory pool we also have contention for the global heap. It cannot in any way compare to the performance of the Win API HeapCreate/HeapDestroy and HeapAlloc/HeapFree. Sturla