Horton

Re: strange parallel query behavior after OOM crashes

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Kuntal Ghosh <kuntalghosh.2007@gmail.com>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2017-03-31T13:20:33Z
Lists: pgsql-hackers 
On Thu, Mar 30, 2017 at 4:35 PM, Kuntal Ghosh
<kuntalghosh.2007@gmail.com> wrote:
> 2. the server restarts automatically, initialize
> BackgroundWorkerData->parallel_register_count and
> BackgroundWorkerData->parallel_terminate_count in the shared memory.
> After that, it calls ForgetBackgroundWorker and it increments
> parallel_terminate_count.

Hmm.  So this seems like the root of the problem.  Presumably those
things need to be reset AFTER forgetting any background workers from
before the crash.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Add an Assert() to max_parallel_workers enforcement.

  2. Fix confusion of max_parallel_workers mechanism following crash.

  3. Add max_parallel_workers GUC.