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.GA2016666@rfd.leadboat.com
Branch
------
REL_10_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/6d81e3c6526b6db229a68dde35593dda230e449f
Modified Files
--------------
src/Makefile.global.in | 4 +-
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 +-
src/test/perl/PostgresNode.pm | 182 +++++++++++++++++++-----
src/test/recovery/t/017_shm.pl | 200 +++++++++++++++++++++++++++
src/tools/msvc/vcregress.pl | 1 +
11 files changed, 524 insertions(+), 179 deletions(-)