[ale] tech "magic"

Geoffrey lists at serioustechnology.com
Wed May 27 09:18:22 EDT 2009


Rev. Johnny Healey wrote:
> There's a great wikipedia article on unusual software bugs:
> 
> http://en.wikipedia.org/wiki/Unusual_software_bug
> 
> I actually ran into a schroedinbug in an apache config file today.

I actually identified a bug in an old c compiler on SVR3 years ago that 
would be defined as a heisenbug.  A piece of code was dropping core at a 
particular point.  I put in a printf and a comment above it, recompiled 
and it ran fine.  Remove the printf and comment, drops core.  We finally 
figured out that we could remove the printf and leave the comment in the 
code and the code would run.  Remove the comment and it would drop core. 
  We eventually simply placed a comment that said something like:

/* don't remove this comment, the code will drop core with out it */

> 
> -Johnny
> 
> On Tue, May 26, 2009 at 10:07 PM, Jim Kinney <jim.kinney at gmail.com> wrote:
>> Everyone here has had it happen. Something fails and you get called to
>> "take a look at it". You get there. take it and it isn't working. So
>> you methodically take it apart, inspecting everything alonmg the way
>> looking for failure points and find
>>
>>
>> nothing
>>
>>
>>
>> it all looks fine
>>
>>
>>
>> So you start testing a few thing as you put it back together.
>>
>>
>>
>> all the parts work correctly even though 20 minutes ago they were all
>> totally dead
>>
>>
>>
>> Finally you plug in the reassembled device and it comes up normally
>> and works perfectly.
>>
>>
>>
>> The 3Com switch I noted last Thursday that likely had a dead power
>> supply just ran me through that exact process. It works fine now.
>> Power supply puts out a rock solid 14V (no load) and 12.01V at 10A
>> load. All the fans work just fine.
>>
>> At least I don't have to explain "what I fixed" in an invoice...
>>
>> --
>> --
>> James P. Kinney III
>> Actively in pursuit of Life, Liberty and Happiness
>> _______________________________________________
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>> Ale at ale.org
>> http://mail.ale.org/mailman/listinfo/ale
>>
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> 


-- 
Until later, Geoffrey

Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety.
  - Benjamin Franklin


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