There are several disadvantages to installing a SIGCHLD handler
- Signals aren't reliable so you may not get one for every child expiry. Using waitpid in a loop will help
- You can get SIGCHLDs from your children when they haven't died
(eg your child gets sent a SIGSTOP - the parent will get a SIGCHLD)
- You can get SIGCHLDs from perl operations like open "|.." and backticks if you are unlucky which can confuse things.
- Unreliable signals are evil!
Some of the examples in The Perl Cookbook have the correct
waitpid in a loop in the SIGCHLD handler, but some don't (for instance the section on
a preforking daemon).
Personally I would ignore SIGCHLD and make the parent wait()
for the children to die. It will be nicely blocked (ie not using any
excess CPU) until it needs to do something (ie make more children).