From: ara.t.howard@...
Date: 2007-01-24T07:11:05+09:00
Subject: Re: Does Ruby's FTP lib have a ghostly bug?

On Wed, 24 Jan 2007, S. Robert James wrote:

> I just added FTP conneciton caching, which seems to have removed the
> problem.  Therefore, I'll assume that this was *not* a ftp.rb problem,
> but rather connections being refused when too many came in.  (This
> didn't show up on simple command line testing, because the rate was
> much slower.)  I'll add that being that the EOFError message is quite
> cryptic, perhaps whoever maintains ftp.rb could make a more
> comprehnsible error message (along with the actual OS level socket
> error).
>
> I also need to thank Ara.   By asking me what I thought was an obvious
> question (does command line ftp work), he forced me to communicate my
> assumption ("command line works, cryptic error message --> ergo ftp.rb
> problem") and consequently rethink it.  Is the command line doing the
> same thing as the app?  No, it's making a lot fewer connections.
>
> This has served to me as a good lesson in debugging:
> 1. Can you prove the problem is where you think it is?  Expand the
> scope.
> 2. With any bug, there's something that you're wrong about.  Perhaps
> those things which give you the information you are sure of are
> themselves wrong.  That is, don't just look for problems where you see
> them -- look for problems in all of your proofs to get there.
> 3. Last, always tell the problem to someone else.  Having to
> communicate to someone forces you to rethink it.  And if that someone
> else wants proof (like most good Rubyists), it forces you to prove it.
> In this case, when I glanced at the src code, I thought it _did_ cache
> the connections. But I was going to paste that line in to the list and
> saw that, in this scenario, it wasn't caching them.
>
> Thanks Ara! And thanks comp.lang.ruby!
>

right on.  you can thank my friend tom lauren.  we used to debug together and
he was such a bastard: i'd say something like, "here x is 42" and he just
wouldn't believe __anything__ i said unless he could prove it __himself__ in
the debugger.  the thing i learned though, was that he always found the bug!

cheers.

-a
-- 
we can deny everything, except that we have the possibility of being better.
simply reflect on that.
- the dalai lama