Question

The following code

require 'timeout'

begin
  timeout(20) do              # Line 4
    result = `hostname`
  end                         # Line 6
rescue Timeout::Error
  puts "Timeout"
  exit
end

puts "Result:" + result       # Line 12

throws the error

issue.rb:12:in <main>': undefined local variable or methodresult’ for
main:Object (NameError)

but if I comment out the timeout element (lines 4 and 6), it works fine. I have tried using IO.popen, IO.select etc but none of this helps. I’ve used this timeout technique in many other areas and it worked fine.

It doesn’t appear to be related to the timeout value as I have experimented with much larger and smaller values.

Am using Ruby 1.92 on Windows XP. Any help much appreciated.

p.s. My original problem was not running “hostname” but a more complex SQL Server batch job. As a bonus point, would a long running system task that exceeded the timeout be automatically killed? I have read lots of posts about the timeout library not honouring timeouts when busy running system tasks?

Answer 1

The result variable is being defined inside the timeout block, so it’s not visible in the outer scope. You should initialize it before:

result = nil 
begin
  timeout(20) do              # Line 4
    result = `hostname`
  end                         # Line 6
rescue Timeout::Error
...