APM: system call hangs

[Bakken, Tom - Temple, TX]

perl -v = This is perl, version 5.005_03 built for MSWin32-x86-object

Surprise?!!???!!  Bill, you hit the nail on the head.  I've got a newer
version on another machine I should be able to use instead.

Thanks for all your help.  

Tom Bakken

-----Original Message-----
From: Bill Raty [mailto:bill.raty at gmail.com] 
Sent: Thursday, July 22, 2004 11:33 AM
To: Bakken, Tom - Temple, TX
Subject: Re: APM: system call hangs


What version of perl?  Activestate perl has support 'fork' since
5.6.mumble .  Please post results of perl -v

Regards,

-Bill

On Thu, 22 Jul 2004 07:45:41 -0600, Bakken, Tom - Temple, TX
<tom.bakken at tx.usda.gov> wrote:
> The system I'm running this on (Windows 2000 Server) doesn't seem to
> support fork.  I'm digging through the ActivePerl documentation and
> there seems to be some support for emulating UNIX.  I tried:
> 
> use POSIX qw(setsid);
> use POSIX qw(:errno_h :fcntl_h);
> 
> But that didn't help.  Is there another module that would work?
> 
> I appreciate your help.
> 
> -----Original Message-----
> From: Bill Raty [mailto:bill.raty at gmail.com]
> Sent: Wednesday, July 21, 2004 10:50 AM
> To: Bakken, Tom - Temple, TX
> Subject: Re: APM: (no subject)
> 
> Tom,
> 
> "System" is itself a form of IPC that has been neatly bundled to cover
> the majority case usage (running a well behaved short-lived
> subprocess).  However you're needing behavior that isn't exactly
> covered by "system".
> 
> Take a look at the 2nd edition of the Perl Cookbook, especially the
> piped open commands.  You'll probably also need to fork off a process
> to do the reading so that your parent process can control how long it
> is willing to wait.
> 
> You may also be able to tap directly into the Windows API via the COM
> module that are supplied with ActiveState perl interpreter, rather
> 
> -- BEGIN SHAMELESS PLUG --
> I'll be presenting some syntactic sugar to sweeten the experience of
> controling child processes at Perl monger's tonight.
> -- END SHAMELESS PLUG --
> 
> Here is example code that I'll be covering tonight which spawns off a
> child process and terminates it after five seconds.  First the
> syntactic sugar subroutine:
> 
>   sub spawn (&) {
>     my ($coderef) =  @_;
>     my $pid;
>     unless ($pid = fork) {
>       # start the child process.  make sure we exit too!
>       $coderef->();
>       exit;
>     }
>     # make sure we don't have ghost processes.  Have perl do the
waitpid
>     $SIG{CHLD} = "IGNORE";
>     # return the process id of the child process.
>     return $pid;
>   }
> 
> #############################
> # Now the using code
> #############################
> # start a process to count from 1 to 100 in 1 second intervals.
> Interrupt it
> # after 5 seconds
> my $kidpid = spawn {
>   # this is running in a different process
>   foreach (1 .. 100) {
>     print "$_\n";
>     sleep 1;
>   }
> };  # <--- REMEMBER THE SEMICOLON HERE!!!
> 
> # let child run for 5 seconds, then stop it.
> sleep 5;
> kill TERM => $kidpid;
> 
> __END__
> 
> In your case you'd probably put the system call inside the curly
> braces after the 'spawn' invocation.  You'll probably need to include
> the code that acts upon  the status code from the 'system' command
> into the curly as well, since that is running in a separate perl
> process.
> 
> On Wed, 21 Jul 2004 08:12:46 -0600, Bakken, Tom - Temple, TX
> <tom.bakken at tx.usda.gov> wrote:
> > I'm having trouble with the perl "system" function.  Actually system
> > works fine.  It's the windows 2000 server programs it runs that are
> > giving me fits.  When I do this:
> >
> > $Status = system("uptime \\\\$MachineName > /nul");
> > Or
> > $Status = system("if exist p:\nul net use p: /d");
> >
> > For example, the uptime or net use will sometimes hang or stall.
How
> > can I kill these and continue without aborting the entire program?
> >
> > I've looked through some of the texts regarding interprocess
> > communications but I'm not sure that's the way I should go.
> >
> > Tom Bakken
> >
> >
> >
> 
> 
>
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