| Oh, you mean like the calling conventions on the IBM Mainframe where a dump
| produces a trace back up the call chain to the calling program(s)? Not to
| mention the trace stack kept within the OS itself for problem solving
| (including system calls or SVC's as we call them on the mainframe). And
| when all else fails, there is the stand alone dump program to dump the whole
| system?
|
| Mainframes have been around for years. It's interesting to see "open
| systems" take on mainframe characteristics after all this time....
All these obsolete ideas. Stack tracebacks. Feh!
Years back at Smarts, a company since acquired by the "EMC" you see in
my email address, one of the things I added to the system was a set of
signal handlers which would print a stack trace. The way to do this was
very non-uniform: On Solaris, you had to spawn a standalong program
(but you got a stack trace of all threads). On HPUX, there was a
function you could call in a system library. On AIX (you'd think IBM,
of all vendors, would do better!) and Windows, we had to write this
ourselves, with varying degrees of OS support. We also dump - shock!
horror! - the values in all the registers. And we (try to) produce a
core dump.
My experience has been that of crashes in the field, 90% can be fully
analyzed based on what we've written to the log file. Of the rest, some
percentage - this is harder to estimate because the numbers are lower; -
can be fully analyzed using the core dump. The rest basically can't be
analyzed without luck and repetition. (I used to say 80-90% for "can be
analyzed from core file", but the number is way down now because (a)
we've gotten better at getting information into and out of the log files
- e.g., we now keep a circular buffer of messages, including those at
too low a severity level to be written to the log, and dump that as
part of the failure output); (b) the remaining problems are exactly the
ones that the current techniques fail to handle - we've fixed the
others!)
-- Jerry
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