Standard PreFork uses the typical double-fork method in UNIX for generating daemons so as to avoid zombies (or more specifically needing to deal with them). However, forking Interchange daemons is relatively expensive.

For most (if not all) sane, modern Unixen, you can avoid the relative expense of double forking by setting SIGCHLD to IGNORE in the master, which accomplishes roughly the same goal. It states, essentially, that the parent is not interested in the result of the child's process, so don't zombify my kids waiting for me to check on them.