Another problem with mmap is that there is no good way to handle I/O errors.
The application will get a signal (SIGSEGV/SIGBUS, can't remember), and no information about what the problem could possibly be. Most applications do not catch these signals and will instead just terminate.
Even if you do catch the signal there is a real challenge to know what caused the signal and to keep consistent book-keeping to be able to perform any sane action in response.
At a previous employer we started seeing this problem when scaling things in production which was no fun.
The application will get a signal (SIGSEGV/SIGBUS, can't remember), and no information about what the problem could possibly be. Most applications do not catch these signals and will instead just terminate.
Even if you do catch the signal there is a real challenge to know what caused the signal and to keep consistent book-keeping to be able to perform any sane action in response.
At a previous employer we started seeing this problem when scaling things in production which was no fun.