Re: Printing backtrace of postgres processes

On 2024-Feb-09, Michael Paquier wrote:

> Anyway, I've been digging around the signal-safety of backtrace(3)
> (even looking a bit at some GCC code, brrr), and I am under the
> impression that backtrace() is just by nature not safe and also
> dangerous in signal handlers. One example of issue I've found:
> https://github.com/gperftools/gperftools/issues/838
>
> This looks like enough ground to me to reject the patch.

Hmm, but the backtrace() manpage says

• backtrace() and backtrace_symbols_fd() don't call malloc() explic‐
itly, but they are part of libgcc, which gets loaded dynamically
when first used. Dynamic loading usually triggers a call to mal‐
loc(3). If you need certain calls to these two functions to not
allocate memory (in signal handlers, for example), you need to make
sure libgcc is loaded beforehand.

and the patch ensures that libgcc is loaded by calling a dummy
backtrace() at the start of the process.

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