testing that processes terminate

[Kevin Scaldeferri]

I recently had to deal with a bug where under certain circumstances a 
server process would never terminate, but would block indefinitely in 
the shutdown process.  Being a good coder, I wrote a unit test to 
reproduce the problem before I fixed it.  The test is happy when I run 
it normally, and even when I run it under Devel::Cover, but it 
consistently fails in our nightly test run (under Devel::Cover).  As 
best I can figure, Devel::Cover is slowing things down so much that my 
test thinks the process doesn't exit.

Here's what the test looks like:
if (my $pid = fork) {
  eval 'use Test::More qw(no_plan)';
  sleep 1;
  # interact with server (child process)
  # ...
        
  kill TERM => $pid;
  my $kid;  my $c = 0;
  while (($kid = waitpid($pid, WNOHANG)) == 0) {
    last if $c > 10;  # really long because Devel::Cover is slooooow!
    sleep 1;
    $c++;
  }
  if ($kid > 0) {
    if ($?) {
      fail("Child died with $?\n");
    } else {
      pass("Child exited");
    }
  } else {
    fail("Child did not exit");
    kill 9 => $pid;
  }
} else {
   # run server process
}
So, as you can see, I interact with the child process in a way to 
tickle the bug, then send it a shutdown signal, then wait for 10 
seconds for it to terminate.  Unfortunately, it's seeming like even 10 
seconds is not enough sometimes.

Does anyone have a suggestion of how else to do this type of test?  Is 
there some good way that I could figure out if the process is blocking 
indefinitely or just running the shutdown very slowly?


Thanks,
Kevin