Re: BUG #16129: Segfault in tts_virtual_materialize in logical replication worker

On Thu, Nov 21, 2019 at 06:01:52PM +0100, Tomas Vondra wrote:
> On Thu, Nov 21, 2019 at 05:35:06PM +0100, Ondřej Jirman wrote:
> > On Thu, Nov 21, 2019 at 05:09:06PM +0100, Tomas Vondra wrote:
> > 
> > > On Thu, Nov 21, 2019 at 04:57:07PM +0100, Ondřej Jirman wrote:
> > > > On Thu, Nov 21, 2019 at 04:27:32PM +0100, Tomas Vondra wrote:
> > > > > On Thu, Nov 21, 2019 at 04:07:16PM +0100, Ondřej Jirman wrote:
> > > > > > I've also managed to get valgrind output on the segfaulting process:
> > > > > >
> > > > > > https://megous.com/dl/tmp/valgrind-105524-109020.log
> > > > > >
> > > > > > Though it probably doesn't show much new.
> > > > > >
> > > > >
> > > > > Is postgres actually compiled with valgrind support? What does pg_config
> > > > > say?
> > > >
> > > > I don't see any valgrind related options in configure --help, I repackaged it
> > > > just with CFLAGS set to -ggdb -Og.
> > > >
> > > 
> > > You need to use -DUSE_VALGRIND or edit pg_config_manual.h. I usually
> > > just use
> > > 
> > >   CFLAGS="-DRANDOMIZE_ALLOCATED_MEMORY -DUSE_VALGRIND -O0 -ggdb"
> > > 
> > > which does the trick. Without the USE_VALGRIND defined, we don't include
> > > the valgrind instrumentation, so I suppose the previous results are bogus.
> > 
> > Two new valgrind logs, now with -DUSE_VALGRIND:
> > 
> > https://megous.com/dl/tmp/valgrind-172090.log
> > https://megous.com/dl/tmp/valgrind-172143.log
> > 
> 
> Unfortunately, I only get HTTP 403 :-(

Sorry for that, it should be accessible now.

> > A lots of uninitialized 1b accesses around VARATT_IS_EXTERNAL_EXPANDED.
> > 
> > So slot->tts_values[natt] is probably uninitialized.
> > 
> > Which is why the backtrace had a weird value there, I guess.
> > 
> 
> Possibly. Something is clearly wrong.
> 
> 
> regards
> 
> -- 
> Tomas Vondra                  http://www.2ndQuadrant.com
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services