our $ALREADY_CONNECTED = 0; # this var's purpose is called a semaphore

DOCUMENT:
for my $document (@collection) {
    if (!$ALREADY_CONNECTED) {
        open2(...); # and save the handles for later usage
        $ALREADY_CONNECTED = 1; # whoa! magic!
        redo DOCUMENT;
    } else {
        # blah blah process $document here,
        # the in/out handles exist.
    };
};