Consistently test for in-use shared memory. postmaster startup scrutinizes any shared memory segment recorded in postmaster.pid, exiting if that segment matches the current data directory and has an attached process. When the postmaster.pid file was missing, a starting postmaster used weaker checks. Change to use the same checks in both scenarios. This increases the chance of a startup failure, in lieu of data corruption, if the DBA does "kill -9 `head -n1 postmaster.pid` && rm postmaster.pid && pg_ctl -w start". A postmaster will no longer stop if shmat() of an old segment fails with EACCES. A postmaster will no longer recycle segments pertaining to other data directories. That's good for production, but it's bad for integration tests that crash a postmaster and immediately delete its data directory. Such a test now leaks a segment indefinitely. No "make check-world" test does that. win32_shmem.c already avoided all these problems. In 9.6 and later, enhance PostgresNode to facilitate testing. Back-patch to 9.4 (all supported versions).
Reviewed (in earlier versions) by Daniel Gustafsson and Kyotaro HORIGUCHI. Discussion: https://postgr.es/m/20190408064141.ga2016...@rfd.leadboat.com Branch ------ REL9_4_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/3ef5e16c618177160bc5f95216dccab3588defdc Modified Files -------------- src/backend/port/sysv_shmem.c | 269 +++++++++++++++++++++--------------- src/backend/port/win32_shmem.c | 7 +- src/backend/postmaster/postmaster.c | 12 +- src/backend/storage/ipc/ipci.c | 14 +- src/backend/utils/init/postinit.c | 6 +- src/include/storage/ipc.h | 2 +- src/include/storage/pg_shmem.h | 6 +- 7 files changed, 175 insertions(+), 141 deletions(-)
