Thread: [COMMITTERS] pgsql: Move isolationtester's is-blocked query into C code for speed.
[COMMITTERS] pgsql: Move isolationtester's is-blocked query into C code for speed.
From
Tom Lane
Date:
Move isolationtester's is-blocked query into C code for speed. Commit 4deb41381 modified isolationtester's query to see whether a session is blocked to also check for waits occurring in GetSafeSnapshot. However, it did that in a way that enormously increased the query's runtime under CLOBBER_CACHE_ALWAYS, causing the buildfarm members that use that to run about four times slower than before, and in some cases fail entirely. To fix, push the entire logic into a dedicated backend function. This should actually reduce the CLOBBER_CACHE_ALWAYS runtime from what it was previously, though I've not checked that. In passing, expose a SQL function to check for safe-snapshot blockage, comparable to pg_blocking_pids. This is more or less free given the infrastructure built to solve the other problem, so we might as well. Thomas Munro Discussion: https://postgr.es/m/20170407165749.pstcakbc637opkax@alap3.anarazel.de Branch ------ master Details ------- http://git.postgresql.org/pg/commitdiff/511540dadf1166d80b864f63979178f324844060 Modified Files -------------- doc/src/sgml/func.sgml | 27 ++++++- src/backend/storage/lmgr/predicate.c | 50 +++++++++++++ src/backend/utils/adt/lockfuncs.c | 119 ++++++++++++++++++++++++++++++ src/include/catalog/catversion.h | 2 +- src/include/catalog/pg_proc.h | 6 +- src/include/storage/predicate_internals.h | 2 + src/test/isolation/.gitignore | 1 + src/test/isolation/isolationtester.c | 12 +-- 8 files changed, 206 insertions(+), 13 deletions(-)