| From: | Kuntal Ghosh <kuntalghosh(dot)2007(at)gmail(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: strange parallel query behavior after OOM crashes |
| Date: | 2017-04-03 10:08:56 |
| Message-ID: | CAGz5QCJ1MEKYzGnOJxWHK039ToKQVnj=BrT7BiQiAzH-jTgZrA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Mar 31, 2017 at 6:50 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Thu, Mar 30, 2017 at 4:35 PM, Kuntal Ghosh
> <kuntalghosh(dot)2007(at)gmail(dot)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.
>
IMHO, the fix would be not to increase the terminated parallel worker
count whenever ForgetBackgroundWorker is called due to a bgworker
crash. I've attached a patch for the same. PFA.
--
Thanks & Regards,
Kuntal Ghosh
EnterpriseDB: http://www.enterprisedb.com
| Attachment | Content-Type | Size |
|---|---|---|
| 0001-Fix-parallel-worker-counts-after-a-crash.patch | binary/octet-stream | 1.8 KB |
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