From: James Edward Gray II <james@...>
Date: 2005-11-17T00:49:58+09:00
Subject: Re: DRb Crashing

On Nov 16, 2005, at 9:42 AM, Hugh Sasse wrote:

> On Thu, 17 Nov 2005, James Edward Gray II wrote:
>
>
>> On Nov 15, 2005, at 6:50 PM, Hugh Sasse wrote:
>>
>>
>>> On Wed, 16 Nov 2005, James Edward Gray II wrote:
>>>
>>>
>>>
>>>> If I launch this server:
>>>>
>>>>
>>>        [...]
>>>
>>>
>>>> __END__
>>>>
>>>> Then run this client:
>>>>
>>>> #!/usr/local/bin/ruby -w
>>>>
>>>> require "drb"
>>>> require "rinda/tuplespace"
>>>>
>>>> DRb.start_service
>>>> tuplespace = Rinda::TupleSpaceProxy.new(
>>>> DRbObject.new_with_uri("druby://localhost:61676")
>>>> )
>>>>
>>>> while problem = tuplespace.take(["Problem", %r{^\d+(?: [-+*/] \d 
>>>> +)+$}])
>>>> tuplespace.write(["Result", "#{problem.last} = #{eval  
>>>> problem.last}"])
>>>> end
>>>>
>>>> __END__
>>>>
>>>> The client crashes, generally within a few seconds.  Adding a  
>>>> sleep inside
>>>> the
>>>> server loop seems to resolve the issue.
>>>>
>>>> Anyone know why?
>>>>
>>>>
>>>
>>> No, I don't. What happens if you match the old way? Like:
>>>  while problem = tuplespace.take(["Problem", nil])
>>>
>>
>> The Regexp is pretty critical in this case.  It validates the data  
>> before an
>> otherwise dangerous call to eval().
>>
>
>   while problem = tuplespace.take(["Problem", nil])
>     unless problem.last =~ %r{^\d+(?: [-+*/] \d+)+$}
>       puts "Bogus input \'#{problem.last}\', Ted!" #:-)
>     else
>       tuplespace.write(["Result", "#{problem.last} = #{eval  
> problem.last}"])
>     end
>   end

This is not equivalent.  You removed the problem from the TupleSpace  
whereas my version leaves it for someone else to solve.

I realize this isn't what you were originally asking for and I can  
try the change, if you want to see it.  To me it's irrelevant though,  
because TupleSpace supports a Regexp search and it should not be  
crashing when doing it.

This is just a simplified case I cooked up to show the issue.

James Edward Gray II