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 backenddied abnormally and
possiblycorrupted shared memory.I have rolled back the current transaction and amgoing to terminate your database
systemconnection and exit.Please reconnect to the database system and repeat your query.
 
server closed the connection unexpectedlyThis probably means the server terminated abnormallybefore or while processing
therequest.
 
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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