From: "Ara.T.Howard" <ahoward@...>
Date: 2004-04-28T13:34:03+09:00
Subject: Re: DRb & thread blocking.

On Wed, 28 Apr 2004, Ken Hilton wrote:

ken-

so far, this seems to work fine on my box?  what's you platform/arch/ruby
version, etc?

-a

> Greetings,
> 
> I added a post earlier today in hopes someone might know right off hand why
> the Ruby progam I've written was not functioning as expected.  I didn't have
> a lot to go on, nor to share so someone could advise me.  So, I spent some
> time stripping my problem child down to its bare minimum and the problem is
> persisting.  Can anyone explain to my why this little program seems to block
> DRb from responding to calls when a thread in the same app has called
> gets()?  Here's the code & instructions.  Thanks in advance for any insight
> you can provide.  I hope to return the favor in the future.
> 
> --------------------------
> # app.rb
> # Instructions: run this program (app.rb) in one shell THEN run
> # myclnt.rb in a separate shell.  If the call to "gets" at line
> # 43 (below) is active, calls to MyServer::service from myclnt.rb
> # seem to be blocked.  Pressing [enter] (w/a short sleep provided
> # to better illustrate the problem), allows the DRb calls from
> # myclnt.rb to be processed, that is right up until the next call
> # to gets.  Commenting out the call to gets, re-running app.rb,
> # and then re-running myclnt.rb shows the problem has "gone away."
> #
> 
> require 'thread'
> require 'drb'
> 
> # MyServer handles calls from myclnt.rb - just returns an I'm alive message.
> class MyServer
>  def service
>   "MyServer is alive!!!"
>  end
> end
> 
> class App
> 
>  def initialize()
>   # array of threads, 1 for DRb and 1 for my command loop,
>   @services = []
>  end
> 
>  def run()
> 
>   # Start MyServer service and store thread.
>   svr = MyServer.new();
>   DRb.start_service('druby://localhost:9000', svr);
>   @services << DRb.thread;
> 
>   # Start command loop. *** When "gets" is called DRb appears to block:.
>   # calls to it from myclnt.rb stall until enter is pressed, thereby
>   # giving enough cycles to DRb.thread to respond to the request?!?!?
>   @services << Thread.new {
>    while true
>     print "Prompt> "
>     # comment out the next line and then rerun app.rb and myclnt.rb
>     #exit if gets.chomp() == "exit";
>     sleep(1)
>    end
>   }
> 
>   @services.each {|svc| svc.join()}
>  end
> 
> end
> 
> App.new().run();
> 
> --------------------------
> 
> # myclnt.rb
> require 'drb'
> 
> puts "Running my client..."
> DRb.start_service(nil,nil)
> 
> while true
>  svr = DRbObject.new(nil, 'druby://localhost:9000')
>  puts "Calling server..."
>  puts "Server returned: " + svr.service;
> end
> 
> 
> 

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