Re: errbacktrace

On Tue, 25 Jun 2019 at 06:08, Peter Eisentraut <
peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:

> New thread continuing from
> <
> https://www.postgresql.org/message-id/d4903af2-e7b7-b551-71f8-3e4a6bdc2e73@2ndquadrant.com
> >.
>
> Here is a extended version of Álvaro's patch that adds an errbacktrace()
> function. You can do two things with this:
>
> - Manually attach it to an ereport() call site that you want to debug.
>
> - Set a configuration parameter like backtrace_function = 'int8in' to
> debug ereport()/elog() calls in a specific function.
>
> There was also mention of settings that would automatically produce
> backtraces for PANICs etc. Those could surely be added if there is
> enough interest.
>
> For the implementation, I support both backtrace() provided by the OS as
> well as using libunwind. The former seems to be supported by a number
> of platforms, including glibc, macOS, and FreeBSD, so maybe we don't
> need the libunwind suport. I haven't found any difference in quality in
> the backtraces between the two approaches, but surely that is highly
> dependent on the exact configuration.
>
> I would welcome testing in all direction with this, to see how well it
> works in different circumstances.
>
>
Hi Peter,

This is certainly a very useful thing. Sadly, it doesn't seem to compile
when trying to use libunwind.
I tried it in a Debian 9 machine with gcc 6.3.0 and debian says i installed
libunwind8 (1.1)

./configure --prefix=/home/jcasanov/Documentos/pgdg/pgbuild/pg13
--enable-debug --enable-profiling --enable-cassert --enable-depend
--with-libunwind

at make i get these errors:
"""
utils/error/elog.o: En la función `set_backtrace':
/home/jcasanov/Documentos/pgdg/projects/postgresql/src/backend/utils/error/elog.c:847:
referencia a `_Ux86_64_getcontext' sin definir
/home/jcasanov/Documentos/pgdg/projects/postgresql/src/backend/utils/error/elog.c:848:
referencia a `_Ux86_64_init_local' sin definir
/home/jcasanov/Documentos/pgdg/projects/postgresql/src/backend/utils/error/elog.c:850:
referencia a `_Ux86_64_step' sin definir
/home/jcasanov/Documentos/pgdg/projects/postgresql/src/backend/utils/error/elog.c:861:
referencia a `_Ux86_64_get_reg' sin definir
/home/jcasanov/Documentos/pgdg/projects/postgresql/src/backend/utils/error/elog.c:862:
referencia a `_Ux86_64_get_proc_name' sin definir
collect2: error: ld returned 1 exit status
make[2]: *** [postgres] Error 1
make[1]: *** [all-backend-recurse] Error 2
make: *** [all-src-recurse] Error 2
"""
--
Jaime Casanova www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services