From: Nathaniel Talbott <ntalbott@...>
Date: 2000-12-29T05:36:31+09:00
Subject: [ruby-talk:8195] Re: Inexplicable core dump

> > I have some code that looks like this:
> >
> > 14	def update(channel, value=nil)
> > 15		@channels[channel].each {
> > 16			| key, proc |
> > 17			if (proc.arity == 0)
> > 18				proc.call
> > 19			else
> > 20				proc.call(value)
> > 21			end
> > 22		} if ( ! @channels[channel].nil? )
> > 23	end
> >
> > The first time it gets called in my code where proc.arity !=
> > 0 (i.e. it goes
> > into the else branch) it does one of these:
> >
> > 	./Tuner.rb:20: [BUG] Segmentation fault
> > 	ruby 1.6.2 (2000-12-25) [i686-cygwin]
> > 	      0 [sig] ruby 120 stackdump: Dumping stack trace
> > to ruby.exe.stackdump
> > 	Aborted (core dumped)
>
> Hmmm... well, I have some more info. First of all, the bug
> came back, so the
> blank line fix didn't really fix things. I've dug into it a
> bit more, and it
> looks like I was sort of barking up the wrong tree. Things
> are core dumping
> AFTER the proc returns. Turns out it always core dumps after
> calling the
> same proc. Here's the proc (well, it's really a method; passed with
> &method(:resultChanged), which might have some bearing, but
> I'm not sure):
>
> 	def resultChanged(result)
> 		@result = result
> 		$defout.write(".")
> 	end
>
> It's kind of complex, but basically this only fails if I've written
> something large out (using puts) somewhere else. The core
> dump seems to be
> caused somehow by the return value value of the method (which
> is always 1 as
> far as I can tell) because this always (at least so far) works:
>
> 	def resultChanged(result)
> 		@result = result
> 		$defout.write(".")
> 		return nil
> 	end

Aargh! I was wrong. The method is not being called. I was confused by the
'.' I was writing out and the one Ruby puts out when it prints a backtrace,
such as './Tuner.rb : 23'. Clearly my dots were crossed.

Back to square one. Ruby is dying intermittently (and can be fixed
temporarily by changing the code in the files) when I 'proc.call' where proc
is a method converted to a proc by &method(:theMethod). Ideas?


Nathaniel

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