Comment by jart

Just because mmap() is commonly used doesn't mean it's commonly understood. Yes, it powers just about everything important in terms of the skeletons of our local systems. So why has the thought of using it occurred to so few people until now? Almost a whole generation has passed since things like mmap() were relegated to "the work's been done!" category of computing. People moved on to caring about things like My Browser and The Cloud where mmap() doesn't exist. Most people don't know about it. The ones who do, are reluctant to use it. Scientific computing projects are totally devoted to supporting MSVC (since you just know data scientists are secretly using those GPUs for gaming) so any thought devs may have had previously about using mmap() would have certainly triggered fears w.r.t. WIN32 before any chance to fully consider the true depth of its value would kick in. Plus data migrations are very difficult to pull off. It worked here due to the outpouring of community support, since people were blocked on this. But for a corporation with tons of cash to burn, it's a harder sell.