Re: Pre-allocation of shared memory ...

Bruce Momjian wrote:
> We already pre-allocate all shared memory and resources on postmaster
> start.

I guess we allocate memory when a backend starts, don't we?
Or do we allocate when the instance starts?

I have two explanations for the following behaviour:

a. a bug
b. not enough shared memory

WARNING: Message from PostgreSQL backend:
The Postmaster has informed me that some other backend
died abnormally and possibly corrupted shared memory.
I have rolled back the current transaction and am
going to terminate your database system connection and exit.
Please reconnect to the database system and repeat your query.
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
connection to server was lost

The problem is that this only happens with mod_perl and Apache on the
same machine so I thought it has to do with a known memory leak in
mod_perl/Apache. I happens after about two weeks (it seems to occur
regularily).

> Are you suggesting pre-acquiring resources like oracle does? Like you start a
> database instance, 350MB memory is gone types?
>
> One thing I love about postgresql is that it does not do any such silly thing.
> I agree in the case you suggest, it makes sense.
>
> If at all postgresql goes that way, I would like to see it configurable. I
> would rather remove an app. from a machine rather than letting it stamp on
> other apps feet.

Shridhar. Yes, when preallocating some memory it has to be configurable
(default = off).

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