Force memory release to the OS

Question

I have an app that takes about 20 MB of ram. In an seldom used algorithm it (std::vector) temporarily allocates 250 MB. After the deallocation the systemmonitor still shows

Answer 1

Use mmap() or VirtualAlloc() to allocate and release memory. This returns it to the OS immediately.

In order to use with std::vector, you'll need to provide it a std::allocator. You might find it easier to hand-roll your own vector w/ placement new and direct destructor invocation.

Normally the system heap allocators handle this correctly for you; however it looks like you found a case where they do not.