[Trilug-ontopic] perl and threads

Greg Brown gwbrown1 at gmail.com
Fri Mar 11 10:04:04 EST 2011

Ok, that sounds logical.  I've never forked a perl script before so I've got
some fun tonight when I get home.  I like this idea, though



On Fri, Mar 11, 2011 at 10:00 AM, Brian Weaver <cmdrclueless at gmail.com>wrote:

> Greg,
> I don't know about using threads, but if you want multiple instances with
> each working on a single device then why not use a master-child process
> model? Have the master fork off N children and maintain a link using
> anonymous pipes, unix sockets, or some other IPC mechanism. The master can
> inform each child on what system to query and then receive a status back
> from the child when it's done.
> Instead of writing the status to a log file the child process could simply
> write the status back to the parent's communication channel. The master
> process can then write to the log file without any fear of multiple writers.
> -- Brian
> On Mar 10, 2011, at 5:07 PM, Greg Brown wrote:
> > Ok, I've GOT to get my scripts using threads.  Here's what I've got and
> what I'd like to do:
> >
> > source: a 3000 line file with hostnames, IP addrs, etc.
> >
> > what script does: logs into each device using Net::SSH::Expect that makes
> configuration changes to IOS devices (uses Net::SSH::Expect rather than
> expect.pm because one of our NMS servers is a windows box and the scripts
> have to run across all NMS servers.. sigh)
> >
> > how script does it: the guts of the script, the real work, is all done in
> a subscript.  The main portion of the script opens the file and creates a
> foreach loop to process each line (and device) one at at time.  As you might
> imagine this script takes a long time to complete.  The subscript returns a
> message to the main script that is written to a log file ("login failed",
> "change implemented", etc).
> >
> > what I'd like to do: take a group of devices, say five at at time, and
> launch the subscript as a thread so I can process more than one device at a
> time.  I would imagine this would involve some kind of flock on the log file
> so two threads couldn't return at the same time.  John B. sent me some
> instructions how to thread a perl script a while back but now I can't find
> it.
> >
> > Does anyone know of a perl book with good and clear examples that use
> threads?
> >
> > Greg
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