On Mon, Aug 2, 2021 at 2:51 AM Andres Freund <and...@anarazel.de> wrote: > which presents a problem: We've initialized all kind of references to shared > memory, own a PGPROC, but have detached from shared memory. > > In practice this will lead pretty quickly to a segfault, because process exit > will run proc_exit callbacks, which in turn will try to do a ProcKill(). Or > logging dereferences MyProc, or ... > > It seems the above code block would need to at least do shmem_exit() before > the PGSharedMemoryDetach()? > > This code has been introduced in > > commit 4d155d8b08fe08c1a1649fdbad61c6dcf4a8671f > Author: Robert Haas <rh...@postgresql.org> > Date: 2014-05-07 14:54:43 -0400 > > Detach shared memory from bgworkers without shmem access. > > Since the postmaster won't perform a crash-and-restart sequence > for background workers which don't request shared memory access, > we'd better make sure that they can't corrupt shared memory. > > Patch by me, review by Tom Lane. > > but before that things were just slightly differently broken...
If you're saying that this code has been 100% broken for 7 years and nobody's noticed until now, then that suggests that nobody actually uses non-shmem-connected bgworkers. I sort of hate to give up on that concept but if we've really gone that many years without anyone noticing obvious breakage then maybe we should. -- Robert Haas EDB: http://www.enterprisedb.com
