[Charter]

Processes in a *nix environment get assigned a PID (process ID number) so $my_pid1 contains that PID when the spider is run, and $my_pid2 looks to see if $my_pid1 still exists. Now PIDs are not unique, but when the spider process terminates, $my_pid2 probably won't return $my_pid1, at least in the short term, indicating that the spider process has ended. If $my_pid1 does not equal $my_pid2, then you'd need to determine whether the spider completed its index correctly or whether the spider ended prematurely. The comments in the code suggest a way to do this check, as I don't always have the time, patience, or energy to write complete code. If you simply do an exec() when $my_pid1 is not equal to $my_pid2, then you restart the spider regardless of how the process ended.