I have done a similar thing to what you describe. Although I have never used open3. I always use Win32::Process to spawn my "children" processes. Below is some code I ripped from some production code which launches several process that all have the same NAME but will obviously have different PIDS. I have to keep the PIDS in an array, each process that I launch also has some kind of unique identifier.

foreach my $md (@chk_mds) {    #@chk_mds is a list of the unique ident
+ifiers (I.e SrvA, SrvB, SrvC etc)
    #Read What Kind of Process to Start.
    if (!&Spawn($md)) {
        &Update_Log("Problems Spawning $proc[0] Process for $md");
    }
    sleep(1);
}

#Re-Spawn the broken Process
sub Spawn
{
    my $rc    = 0;
    my $md     = shift;
    my $result = Win32::Process::Create( $ProcessObj,
                    "$xcall_path/bin/application.exe",
                     "application.exe $md",
                    1, #Inherit Handles.
                    NORMAL_PRIORITY_CLASS,
                    ".") or &Update_Log("DEBUG - Cannot Launch the X-$
+proc process: $!");
        if ($result) {
            my $pid = $ProcessObj->GetProcessID();
            $proclst{$md} = $pid;
            push (@pids, $pid);
            &Update_Log("\@pids = @pids");
            &Update_Log("Launching Call Logger Process for $md with PI
+D - $proclst{$md}");
            $rc = $pid;
        } else {
            &Update_Log("Process for $md NOT successfully Created:" . 
+Win32::FormatMessage(GetLastError()));
        }
    return($rc);
}

#Update Log file
sub Update_Log
{
    my ($ss, $mm, $hh, $d, $mon, $yr) = localtime();
    my $date     = sprintf("%02d-%02d-%04d", $mon+1, $d, $yr+1900);
    my $time        = sprintf("%02d:%02d:%02d", $hh, $mm, $ss);

    #Specify the Logfile Name
    my $logfile     = "$xcall_path/log/X-CallServer$date.log";

    if (open( LOG, ">>$logfile" ) ) {
        my $TempSelect = select( LOG );
        $| = 1;
        select( $TempSelect );
        if (! $_[0]) { return (0); }
        print LOG "$time - $_[0]";
    } else {
        &Event(EVENTLOG_ERROR_TYPE, "X-CallServer Could Not Open Logfi
+le $logfile: $!");
        exit(5);
    }
    close(LOG);
    return(1);
}
[download]

So what I have is a hash (%proclst) of all my application.exe's PIDS. I then have a piece of code that kills these PIDS when the service stops.

foreach my $pid (keys %proclst) {
    Win32::Process::KillProcess($proclst{$pid}, 255);
    &Update_Log("Service Stopping - Stopping $proclst{$pid}");
}
undef %proclst;
[download]

These are only snippets from a larger piece of code, I am using Win32::Daemon for all my service requirements on Win32 also. The Update_Log is a routine that I use to update log files etc.. Really only included so you dont get confused when you see me call it from the Spawn function.

HTH..

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