Re: Crashes with no backtrace when printing

FROM : Jens Alfke
DATE : Fri Jul 04 06:44:21 2008

On 3 Jul '08, at 4:24 PM, Ben wrote:

> Attaching to program: `/Path/goes/here', process 14859.
> Cannot access memory at address 0x9ead7
> Cannot access memory at address 0x9ead7


I've found that gdb-in-Xcode is more reliable at being able to get a 
backtrace if you launch the program with the debugger (i.e. 
"breakpoints enabled"), versus having it try to attach only when the 
process crashes. But it's still not 100%.

It's not clear that this is a problem with gdb, though. Some program 
bugs can corrupt the stack or other areas of memory sufficiently to 
confuse gdb. Those can be a pain to debug. The only thing I can 
suggest is to set a breakpoint as near the point of the crash as you 
can, and then start single-stepping. If you're lucky, at some 
consistent spot the debugger will go blooey as the stack gets wiped 
out; then you can try to figure out what's wrong with the code there.

—Jens_______________________________________________

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