Multi-processing
Multi-processing simply means using processes to do concurrent tasks. A very good example is the Common Gateway Interface (CGI) standard in web servers. The web servers employing this technique launch a new interpreter process for each HTTP request. This way, they can serve multiple requests simultaneously.
On such web servers, for a high throughput of requests, you might see that many interpreter processes are spawned and running at the same time, each of which is handling a different HTTP request. Since they are different processes, they are isolated and cannot see the memory regions of each other. Fortunately, in the CGI use case, the interpreter processes don't need to communicate with each other or share data. But this is not always the case.
There are many examples in which a number of processes are doing some concurrent tasks, and they need to share crucial pieces of information in order to let the software continue functioning. As an example, we...
