heisenbug

heisenbug
 /hi:'zen.buhg/, n.

   [from Heisenberg's Uncertainty Principle in quantum physics] A bug
   that disappears or alters its behavior when one attempts to probe or
   isolate it. (This usage is not even particularly fanciful; the use of
   a debugger sometimes alters a program's operating environment
   significantly enough that buggy code, such as that which relies on the
   values of uninitialized memory, behaves quite differently.) Antonym of
   {Bohr bug}; see also {mandelbug}, {schroedinbug}. In C, nine out of
   ten heisenbugs result from uninitialized auto variables, {fandango on
   core} phenomena (esp. lossage related to corruption of the malloc
   {arena}) or errors that {smash the stack}.
    

heisenbug

   <jargon> /hi:'zen-buhg/ (From Heisenberg's Uncertainty
   Principle in quantum physics) A bug that disappears or alters
   its behaviour when one attempts to probe or isolate it.  (This
   usage is not even particularly fanciful; the use of a debugger
   sometimes alters a program's operating environment
   significantly enough that buggy code, such as that which
   relies on the values of uninitialised memory, behaves quite
   differently.)

   In {C}, nine out of ten heisenbugs result from uninitialised
   auto variables, {fandango on core} phenomena (especially
   lossage related to corruption of the malloc {arena}) or errors
   that {smash the stack}.

   Opposite: {Bohr bug}.  See also {mandelbug}, {schroedinbug}.

   [{Jargon File}]

   (1995-02-28)