I have had a very hard time trying to debug which has hindered my work on 
some projects.  In particular I have had trouble properly grasping how to work 
with debugging multi threaded applications, memory errors, and stack 
corruption. I know that it is not a five minute learning process to absorb such 
knowledge, but I have not yet found helpful references. I have had best luck 
trying to logically guess a location close to the problem, then setting a break 
and walking through the code. Once I hit a segfault, I run through the code 
with a breakpoint bringing me to just before the problem, but do not always 
understand how to go further. Strange things I see look like bad pointer 
addresses or the problems being caused within another thread.
  Since moving to FreeBSD7, I have been unable to use valgrind (which did not 
seem to help much on multi threaded apps) and I have not found a way to test 
binaries in the work directories and have had to install it to test it. At 
present, either gdb alone or kdbg seem to be the only ways I have been able to 
get even partially reliable responses from gdb because other interfaces 
disregard breakpoints and interrupts to execution. Are such difficulties common?
  On another similar topic, is there a good place to start learning about 
limitations to system internals, such as kern.ipc.shmmax and why I may 'not' 
want to set it to excessively high values or how other values relate to 
changing it? How can I tell what cap is occurring, whether it be a system limit 
or something controlled within the app such as with pthread_attr_setstacksize() 
and how are 'proper' values determined?
  The books "advanced programming in the unix environment" and "programming 
with posix threads" help me learn the unix world a bit better, but without 
debugging knowledge I find it hard to get anywhere with writing more than my 
high school level of programs and very difficult to get anywhere on the 
projects of others once threads and/or dynamic memory is involved.
  Any suggested course for further study from here?
Thanks again,
Edward Sutton, III

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