Although not directly related to the OP's question, this is still important.
There's a subtle bug in this code that I have seen repeatedly. This code assumes two potential returns from fork. The fork call actually has three potential return values, not two.
- positive integer - pid of child process returned to the parent process
- 0 - returned to the child process
- undef - returned to the parent process if the fork call cailed.
I learned about this when a long-running process started failing when it was moved to a much, much faster machine. It forked enough child processes in a burst to run out of process slots and then failed. Since the return was not true, it went on to do work as a child and exited when it was done. Now, the main process was gone.
Update: As
almut pointed out, the
undef case was dealt with in the
else. I can only say that I'm a little oversensitive to this bug after losing a fair amount of time on the above case.
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