I mentored Giovanni on the two-step allocator patch, and in the process we discovered that on Windows, page tables for all of your reserved address space are counted towards the memory limits of your process. This also affects Go (<a href="https://golang.org/issue/5402" rel="nofollow">https://golang.org/issue/5402</a> and <a href="https://golang.org/issue/5236" rel="nofollow">https://golang.org/issue/5236</a>) which uses a similar trick of reserving virtual address space for its heap. If anyone has ideas for how to deal with this on Windows I think many people would be quite interested :)