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SubjectRe: Anyone working on multi-threaded core files for 2.4 ?


On Fri, 29 Sep 2000, Igmar Palsenberg wrote:

> > I was aiming at the simplest and in my mind most obvious thing, which
> > is to have the standard ELF coreer dump handle multiple threads in the
> > same way as it does on many other systems. The lack of these causes
> > shrieks of amazement from many of our customers :-(
> >
> > This is not rocket science, and there are already debuggers (gdb, our
> > product TotalView, ...) which know how to understand such core dumps
> > if only the kernel produced them.
> >
> > Now that the kernel has mechanisms for finding all the threads in a
> > process, the actual dump writing should be relatively simple. (You
> > need to write the appropriate register notes for every thread, rather
> > than just one).

How about preventing the rest of threads from doing mmap()/munmap()/etc.
while the dump is taken? How about thread A coredumping, half of the image
being already written and thread B (nowhere near the kernel mode, mind
you) changing the data both in the area that is already dumped and area
the still isn't? After that you can look at the dump and notice absolutely
corrupted data structures - very effective in misdirecting your attempts
to figure out what went wrong.

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