| From: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
|---|---|
| To: | Alan Nilsson <anilsson(at)apple(dot)com> |
| Cc: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: shared memory allocation - C function |
| Date: | 2014-04-17 04:56:05 |
| Message-ID: | CAB7nPqR+S-kb8BxJ+nR2+XcKYX-usjpSGsSRtY9NqSsqL2tJKw@mail.gmail.com |
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| Lists: | pgsql-general |
On Thu, Apr 17, 2014 at 8:04 AM, Alan Nilsson <anilsson(at)apple(dot)com> wrote:
> Is it possible to allocate a small chunk of shared memory outside of any
> pools(i.e. manually alloced & de-alloced) that is visible to all processes?
> I would like a small amount to store a mutex and a condition variable that
> is accessible in a c function from any process. Is there an SPI/API to do
> this?
>
You can allocate a custom amount of shared memory at server initialization
using the hook called shmem_startup_hook in ipci.c through a library loaded
with shared_preload_libraries. Why not having a look at
contrib/pg_stat_statements which is a good example?
--
Michael
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