Re: Multiple forks get re-executed

[PrakashK]

You must explicitly terminate the child process that fork created, once it's job is done. Otherwise, it continues to exist.

In your pseudo-code, the code after fork is executed by both the parent and the child. If you want only one of them to do "stuff" (usually child -- that's why you forked, right?), you must explicitly check the return code of fork to determine the identity of the process and assign "work" to it.

fork returns the pid of the child process to the parent, and returns 0 to the child process.

Please see below:

sub RUN
{
  my $arg = shift;
  if (fork) {  # parent process
    # do whatever parent is supposed to do
    wait;
  } else {     # child process
    do stuff on $arg;
    exit;
  }
}

In practice, you should check for possible errors in the fork call. Please see the camel book for an example (p. 715 in 3rd edition).

/prakash

[pltommyo]

Thanks. This is what I ended up using. The code is a generalized subroutine that does a task for my users, but it is at their discretion as to whether they wish to fork or not, as it is also at their discretion to choose where to reap their children. Tommy O