question/problem about forking in expect

question/problem about forking in expect

Post by Cameron Lai » Thu, 01 May 2003 20:55:44


>translating from german to english what i want to say is hard business ...

>i know that  telnet from H0 to H1 and then to get a config from server
>F1 per ftp
>is a very, very stupid example.

>but this is not my focus.
>(for the test i've made few minutes ago i decided to telnet to a host and then
>send a "uname -a" on this host. ;-))

>my focus is on the fork-> Maybe somebody can say due to his/her
>experience if my
>code is right or false?

>i've never tested this script with forking with 500 routers. it's only in my
>testlab with the 3 suns.
>i ve tested a similar script with 30 machines but the load of the
>machine where
>expect runs on increases much.

>page 446: i will think about it. i can't understand it not yet.

To my shame, I don't read German.

I see a couple of issues.  One is how to fork.  Another
is how to manage network monitoring of hundreds of hosts.
All my experience is that [fork]ing is NOT part of the
solution of the latter.  Yes, you need some sort of con-
currency to monitor all your hosts satisfyingly; forking,
though, or even a thread-based concurrency model, will
NOT give the performance and reliability you're after.
You need an event-based model, or, in Unix programming
terms, one founded on select().

That's the subject of page 446.

A couple of tasks remain.  One is to analyze your source
code, and explain why [fork] gives you results that
surprise you.  More urgent than that is to write an
[expect_background] example or two to help you make good
use of this interface in your development work.

It might be a week before Don, I, or someone else can help
you more with these items.