Horton

Re: BUG #15585: infinite DynamicSharedMemoryControlLock waiting in parallel query

Sergei Kornilov <sk@zsrv.org>

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From: Sergei Kornilov <sk@zsrv.org>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Maksim Milyutin <milyutinma@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Date: 2019-04-12T13:48:19Z
Lists: pgsql-bugs 
Hello

Just for archive purposes:

This bug should be already fixed in stable branch and will be shipped in next minor release (11.3 and 10.8). Until the fix is released, the simplest workaround is to disable parallel query with SET max_parallel_workers_per_gather = 0 if you're affected by the bug.
It's a rare timing bug, but some workloads seem to be more prone to it, so unfortunately it went undetected for a long time.

Related discussion and patch was here: https://www.postgresql.org/message-id/flat/20190207014719.GJ29720%40telsasoft.com

regards, Sergei

Commits

  1. Fix race in dsm_attach() when handles are reused.