From: Joel VanderWerf <vjoel@...>
Date: 2006-09-18T07:27:49+09:00
Subject: Re: timeout and ensure

Arnaud Bergeron wrote:
> On 9/17/06, khaines@enigo.com <khaines@enigo.com> wrote:
>> On Mon, 18 Sep 2006, Joel VanderWerf wrote:
>>
>> > I wish I had an easy answer to this problem, but I don't. Are 
>> timeout and
>> > ensure inherently incompatible?
>>
>> I don't have an answer, but what if you make your ensure section into a
>> critical section?
>>
>> ensure
>>    Thread.critical = true
>>    # do stuff
>>    Thread.critical = false
>> end
>>
>>
>> Kirk Haines
> 
> There is still the race problem if the exception gets raised just
> before the Thread.critical.

Confirmed by experiment with ruby 1.8.4:

$ cat ensure-timeout.rb
require 'timeout'

Thread.abort_on_exception = true

work_thread = Thread.new do
   loop do
     begin
       Thread.pass
     ensure
       Thread.critical = true
       begin
       rescue Timeout::Error
         puts "caught a Timeout::Error"
       end
       Thread.critical = false
       #retry
     end
   end
end

loop do
   work_thread.raise Timeout::Error
end

$ ruby ensure-timeout.rb
ensure-timeout.rb:22: Timeout::Error (Timeout::Error)
         from ensure-timeout.rb:6
         from ensure-timeout.rb:5


-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407