wait/waitpid returns -1 when there are no children or the children are automatically being reaped ( according to perldoc -f wait ). So the loop is waiting for all of the children to exit
I personally don't like this child count decrementing business... I'd rather explicitly check if the pid that I just got is the pid that I'm waiting for, i.e., my child. That may just be me...
## XXX - I use hashes in this type of situation
## because I usually associate more meta data to a pid
## which must be used by the parent when the child
## exits... and delete $hash{ $foo } is cleaner
## than splice() to me :)
use POSIX;
my %pids;
for( 1 .. $numchild ) {
my $pid = fork();
## check if $pid id defined, etc.
if( $pid ) { ## parent
$pids{ $pid } = 1;
} else {
do_interesting_stuff();
exit;
}
}
while( ( my $pid = waitpid(-1, POSIX::WNOHANG() ) ) > 0 ){
if( exists $pids{ $pid } ) {
delete $pids{ $pid };
} else {
print STDERR "Unknown child $pid\n";
}
}
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|