| From: | Julien Rouhaud <julien(dot)rouhaud(at)dalibo(dot)com> |
|---|---|
| To: | "hari(dot)prasath" <hari(dot)prasath(at)zohocorp(dot)com> |
| Cc: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: ShmemAlloc maximum size |
| Date: | 2017-02-23 19:55:19 |
| Message-ID: | 20170223195519.GA10384@nol.local |
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| Lists: | pgsql-general |
On Thu, Feb 23, 2017 at 08:17:54PM +0530, hari.prasath wrote:
> I am trying to get some 15MB of shared memory using ShmemAlloc.
>
> Cross checked all my kernal variables set in OS level and also in postgresql.conf.
>
> Cant able to get the required memory(15MB) but if i try with some small memory(1MB), its working fine.
>
> Am i missing something.?
Assuming you're talking about some C extension, you have to request in
_PG_INIT() the amount of shmem you'll need, with RequestAddinShmemSpace().
You can see an example in pg_stat_statements.c how it's done (_PG_INIT() and
pgss_shmem_startup()).
Asking a small amount probably works because some shared memory is requested
but not totally used as soon as the server starts.
Regards.
--
Julien Rouhaud
http://dalibo.com - http://dalibo.org
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