TDM Rerun #11: Shared Pools

Sometimes we run into problems because of a Windows feature, and most of the time this is a very good feature, that a file mapping (an essential part of my shared memory implementation) cannot exist on its own. A file mapping, like mutexes, events, and other Windows primitives, must have an owner. If all processes associated with a given file mapping die, the file mapping will be destroyed. Because in my shared memory implementation this file mapping is backed with a page file, its contents won’t be preserved on an accessible part of the disk.

- Shared Pools, The Delphi Magazine 95, July 2003

The shared pool was one of my more baroque creations. In fact, it was so complicated that it was never used in a deployed application. Basically, the article described an architecture to implement a pool of shared memory objects, which multiple Writers could use to send data to one Reader (typically sitting in another process). The system also handled cleanup when a Reader task died and other management details.

You really should not be playing with this code. There are better solutions.

Links: article (PDF, 193 KB), source code (ZIP, 1.9 MB)