From: ptkwt@...2.teleport.com (Phil Tomson)
Date: 2000-12-19T05:10:02+09:00
Subject: [ruby-talk:7597] timeout question


I need to be able to timeout of an operation that has hung (typically,
it's some command sent to the system [ie. system("someprog")] that I need
to timeout of after a few minutes).  I found the timeout command in the
book (pg 464) and tried it with a toy program:

require "timeout"
returnval = timeout(1.5) do
   sleep(30)
end
print "I'm awake!\n"
print "return value is: #{returnval}\n"

It times out fine, but the problem is that the print commands never get
executed either - the timeout seems to kill not only the operation that
was being timed, but the whole script.

What I need is something that sets a timer and waits for it to complete -
if the timed operation has become 'stuck' I need to kill it when the timer
times out and then continue on with the rest of the program.

Another related question:
In the case of a system call that is being timed, does the process that
was spawned on the system actually get killed?

For example if I have:

retval = timeout(100) do
   system("my_prog -args")
end

If the timer gets to 100 seconds will the program my_prog be sent some
kind of TERM signal? (probably not, but I can only hope - that's what I
would like it to do :)  OK, more realistically, How can I figure out the
pid of the spawned my_prog so I can send a TERM to it when the timer times
out? 

Phil