On Thu, Aug 9, 2018 at 12:59 PM Asim R P <aprav...@pivotal.io> wrote: > On Tue, Aug 7, 2018 at 7:00 PM, Peter Geoghegan <p...@bowt.ie> wrote: > > I wonder if it would be a better idea to enable Valgrind's memcheck to > > mark buffers as read-only or read-write. We've considered doing > > something like that for years, but for whatever reason nobody followed > > through. > > Basic question: how do you mark buffers as read-only using memcheck > tool? Running installcheck with valgrind didn't uncover any errors: > > valgrind --trace-children=yes pg_ctl -D datadir start > make installcheck-parallel
Presumably with VALGRIND_xxx macros, but is there a way to make that work for shared memory? I like the mprotect() patch. This could be enabled on a build farm animal. I guess it would either fail explicitly or behave incorrectly for VM page size > BLCKSZ depending on OS, but at least on Linux/amd64 you have to go out of your way to get pages > 4KB so that seems OK for a debugging feature. I would like to do something similar with DSA, to electrify superblocks and whole segments that are freed. That would have caught a recent bug in DSA itself and in client code. -- Thomas Munro http://www.enterprisedb.com
