Re: pg11.1: dsa_area could not attach to segment

Sergei Kornilov <sk@zsrv.org>

From: Sergei Kornilov <sk@zsrv.org>

To: Justin Pryzby <pryzby@telsasoft.com>, Thomas Munro <thomas.munro@enterprisedb.com>

Cc: "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>

Date: 2019-02-14T16:36:55Z

Lists: pgsql-hackers

Hi

> Do you think that plausibly explains and resolves symptoms of bug#15585, too?

I think yes. Bug#15585 raised only after "dsa_area could not attach to segment" in different parallel worker. Leader stuck because waiting all parallel workers, but one worker has unexpected recursion in dsm_backend_shutdown [1] and will never shutdown. Backtrace show previous error in this backend: "cannot unpin a segment that is not pinned" - root cause is earlier and in a different process.

* https://www.postgresql.org/message-id/70942611548327380%40myt6-7734411c649e.qloud-c.yandex.net

regards, Sergei

Commits

Fix race in dsm_attach() when handles are reused.
- 6c0fb9418925 12.0 landed
- bd195071fd2b 9.4.22 landed
- b7c8766d3480 9.5.17 landed
- cb0680573f7b 9.6.13 landed
- cb3d674e1709 10.8 landed
- faf132449c0c 11.3 landed
Refactor pid, random seed and start time initialization.
- 197e4af9d5da 12.0 cited