| From: | Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com> |
|---|---|
| To: | Stas Kelvich <s(dot)kelvich(at)postgrespro(dot)ru>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Logical replication ApplyContext bloat |
| Date: | 2017-04-19 09:37:25 |
| Message-ID: | 3cde85de-4464-3742-882c-75cd0d5a7528@2ndquadrant.com |
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| Lists: | pgsql-hackers |
On 18/04/17 13:45, Stas Kelvich wrote:
> Hi,
>
> currently logical replication worker uses ApplyContext to decode received data
> and that context is never freed during transaction processing. Hence if publication
> side is performing something like 10M row inserts in single transaction, then
> subscription worker will occupy more than 10G of ram (and can be killed by OOM).
>
> Attached patch resets ApplyContext after each insert/update/delete/commit.
> I’ve tried to reset context only on each 100/1000/10000 value of CommandCounter,
> but didn’t spotted any measurable difference in speed.
>
> Problem spotted by Mikhail Shurutov.
>
Hmm we also do replication protocol handling inside the ApplyContext
(LogicalRepApplyLoop), are you sure this change is safe in that regard?
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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