From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | pgsql-committers(at)postgresql(dot)org |
Subject: | pgsql: Fix leakage of cost_limit when multiple autovacuum workers are a |
Date: | 2010-11-20 03:30:01 |
Message-ID: | E1PJe9J-0001uP-2q@gemulon.postgresql.org |
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Lists: | pgsql-committers |
Fix leakage of cost_limit when multiple autovacuum workers are active.
When using default autovacuum_vac_cost_limit, autovac_balance_cost relied
on VacuumCostLimit to contain the correct global value ... but after the
first time through in a particular worker process, it didn't, because we'd
trashed it in previous iterations. Depending on the state of other autovac
workers, this could result in a steady reduction of the effective
cost_limit setting as a particular worker processed more and more tables,
causing it to go slower and slower. Spotted by Simon Poole (bug #5759).
Fix by saving and restoring the GUC variables in the loop in do_autovacuum.
In passing, improve a few comments.
Back-patch to 8.3 ... the cost rebalancing code has been buggy since it was
put in.
Branch
------
REL8_3_STABLE
Details
-------
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=6cb9d51133a2e42f107074f64fee704c90aa9df9
Modified Files
--------------
src/backend/postmaster/autovacuum.c | 63 +++++++++++++++++++++++++----------
1 files changed, 45 insertions(+), 18 deletions(-)
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