Network Programming with Perl

The Psychotherapist as a Forking Server

We are going to reimplement the psychotherapist program as a forking network server, but before we do so we must discuss issues surrounding the termination of child processes in UNIX-based forking servers. This discussion does not apply to servers running under the Microsoft Windows versions of Perl.

Zombies

We've already used fork(): In Chapter 2 we used it in a toy example to distribute the load of a computation across two child processes (Figure 2.5), and in Chapter 5 we used it to avoid synchronization and deadlock problems in the gab2.pl script (Figure 5.8).

One difference between those examples and the forking server examples in this chapter is the relative longevity of the parent and the child ...