Fix crash in parallel autovacuum when no DSM segment can be created. If no DSM segment can be created, a ParallelContext can still be created with zero workers, but its seg pointer is NULL. Parallel autovacuum registered a segment detach callback on that NULL pointer, crashing the autovacuum worker.
Fix by setting up the shared cost parameters and the detach callback only when the parallel context has workers, as there are no workers to propagate the parameters to otherwise. Oversight in commit 1ff3180ca01. Found by Bharath using AI assisted review with Claude. Reported-by: Bharath Rupireddy <[email protected]> Author: Bharath Rupireddy <[email protected]> Discussion: https://postgr.es/m/calj2acvjbn03fq4xwgkh1zofkapk6-p3ufnlhuhnzcw1zpm...@mail.gmail.com Backpatch-through: 19 Branch ------ REL_19_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/4331d20f4d5cb51663b0912fdb2a3b991bc5a5c8 Modified Files -------------- src/backend/commands/vacuumparallel.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
