Some times you have a need to fork of several children, but you want to
limit the maximum number of children that are alive at one time. Here
are two little subroutines that might help you, mfork and
afork. They are very similar. They take three arguments,
and differ in the first argument. For mfork, the first
argument is a number, indicating how many children should be forked. For
afork, the first argument is an array - a child will be
forked for each array element. The second argument indicates the maximum
number of children that may be alive at one time. The third argument is a
code reference; this is the code that will be executed by the child. One
argument will be given to this code fragment; for mfork
it will be an increasing number, starting at one. Each next child gets
the next number. For afork, the array element is passed.
Note that this code will assume no other children will be spawned, and that $SIG {CHLD} hasn't been set to IGNORE
sub mfork ($$&) { my ($count, $max, $code) = @_; foreach my $c (1 .. $count) { wait unless $c <= $max; die "Fork failed: $!\n" unless defined (my $pid = fork); exit $code -> ($c) unless $pid; } 1 until -1 == wait; } sub afork (\@$&) { my ($data, $max, $code) = @_; my $c = 0; foreach my $data (@$data) { wait unless ++ $c <= $max; die "Fork failed: $!\n" unless defined (my $pid = fork); exit $code -> ($data) unless $pid; } 1 until -1 == wait; }
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Re: Many children, but never more than a fixed number at once.
by gav^ (Curate) on Jun 20, 2002 at 03:05 UTC | |
by Abigail-II (Bishop) on Jul 08, 2002 at 16:33 UTC |
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