Quote Originally Posted by Wokawidget
Memory mapped files?

Woka
I might be using incorrect terminology but it is correct to the extent that this is a common use of the term. I don't know how familiar you are with Memory mapped files, so I should try to define them assuming you know very little. If I don't do that well enough, then say so.

Memory mapped files is a common way for processes to share data; perhaps the most common. It does seem to be an indirect solution, and it probably is, at least somewhat. A Unix system, for example, has more direct functions for sharing memory; at least if my memory is accurate.

When a file is mapped to memory, a portion of memory in each process's address space is mapped to a common portion of virtual memory. The memory can be paged in and out, but that is not done unless physical memory is used to the extent that pages need to be swapped, whether they are part of a memory-mapped file or not. Data in a memory-mapped file can be accessed as efficiently as normal memory in an address space. In terms of efficiency, the memory is the same as the rest of memory for the process. ReadProcessMemory and/or WriteProcessMemory are very inefficient in comparison.

A memory-mapped file can be backed by the pagefile(s), for which the file becomes just a way to share memory. Believe me, that is a solution that is very, very common.