Re^4: Win32 capturing output from a process that may hang

[Random_Walk]

in reply to Re^3: Win32 capturing output from a process that may hang (Updated!)
in thread Win32 capturing output from a process that may hang

Hi BrowserUK

Well you can put your jaundiced view aside for a second here. Your code did not do exactly what I wanted (I caught the wait timeout even if code is done issue) but I have altered it and as far as my testing goes up to now I think I have exactly what I want. Here are the salient fragments

# this is a direct c&p from a larger opus of code
# but you should get the idea.
# command is worked out earlier depending on the 
# platform we are running on

    my $timeout=60;
    my @sqlo;

        my $Q = new Thread::Queue;
        threads->create( 
            \&RunInThread, 
            $command,
            $Q
        );

    my $pid = $Q->dequeue;
    for (1..$timeout) {
        sleep 1;
        my $result=$Q->dequeue_nb; # non_block, return undef if nowt o
+n queue
        next unless $result;       # twas nowt on queue
        if ($result eq "$pid is done") {
            $trace->trace("SQL process finished within $_ seconds");
        last;
        }
            push @sqlo, $result;
    }
    my $killed = kill 9, $pid if kill 0, $pid;  # kill child if still 
+alive
    if ($killed) {
        $trace->trace("Had to kill SQL process, taking more than $time
+out secs");
    } 

sub RunInThread {
    my ( $cmd, $Q) = @_;
    my $pid = open CMD, "$cmd |" or $trace->die("$cmd : $!");
    $Q->enqueue($pid);
    $Q->enqueue( $_ ) while defined( $_ = <CMD> );
    $Q->enqueue("$pid is done");
}

The multithreading is also great as I may have several DBs to examine so a little refactoring and I can do them all in parallel improving the chance of completion within the 120 sec time limit no end.

Cheers,
R.

[BrowserUk]

Neat!++

Sending the pid back to the parent thread and having it do the killing is very shrewd--and obvious. Now you've shown me:)

Thanks for the feedback. I love to learn.