Perl, waiting for non-child process to exit

I have a script which is used to redeploy a couple programs in a custom server environment, (ie: not an established standard container which has code hotswapping). To do this, it takes down the server processes, but these take some time to fully close all their connections. These aren't child processes of the perlscript. They run for hundreds of days at a time normally, so I'd rather not have to wrap the server processes in perlscripts just so I can fork them to shut them down elegantly months or years later.

So currently to wait on them to die during redeployment, I'm parsing the output of ps -ef, grabbing the pid field, killing that pid, waiting 60 seconds, (which seems a reasonable time with these processes), rechecking the ps -ef to make sure they're dead, etc. Go on with copies, chmods, etc.

This solution feels lame/clunky to me. I've google'd all over and have not seen anything on this particular topic; there's a pile of material about waiting on forked children, and waitpid would be perfect if only it operated in this way.

From reading How to wait for exit of non-children processes (which is c specific)I'm guessing there's really not much else I can do, apart from reading /proc/pid instead, but I thought maybe there'd be a perl-specific solution out there somewhere. Any ideas?

回答1:

You can use kill 0, $pid (returns 1 on success and 0 on failure) instead of rechecking ps -ef, but that has the possible gotcha that the pid may have been reused.

If you already have ps-parsing code, it's probably not worth it to switch, but there's Proc::ProcessTable.

Other than that, no ideas.

回答2:

In Unix \ Linux only the parent process gets a signal when a process exits parent process - This is an OS feature, and not language specific.

Other solutions will be equivalent to yours - checking the process table for the existence of the process (although the specific method may vary - like using ps or directly querying the kernel)