From: Eleanor McHugh <eleanor@...>
Date: 2009-06-24T05:31:40+09:00
Subject: Re: Threads + Forks in Ruby 1.9.1p129

On 23 Jun 2009, at 20:17, Roger Pack wrote:
>> On 1.8.6 with green threads a fork() could result in a child process
>> with all the threads present in the parent process, however I know
>> that with the Apple default install of 1.8.6 on Leopard this is not
>> the case. As I don't have the time to dig into the sources right now
>> I'll float the hypothesis that 1.8.6 is being built with pthreads.
>
> running this code:
>
> Thread.new { puts 'hello'; loop { sleep 1; puts 'in 1' +
> Process.pid.to_s} }
> fork {
> puts 'child' + Process.pid.to_s
> sleep
> }
> puts 'parent' + Process.pid.to_s
> sleep
>
> on ruby 1.8.7 [linux, no pthreads] results in only the parent running
> the thread, and also 1.9.2 does the same.  For what it's worth it  
> seems
> that threads really don't run in child processes.

Thank goodness for that. Whilst I much prefer the idea of a forked  
process being a genuine duplicate of its parent (which I think is more  
in line with the original conception of fork) consistency has much to  
commend it.


Ellie

Eleanor McHugh
Games With Brains
http://slides.games-with-brains.net
----
raise ArgumentError unless @reality.responds_to? :reason