HaveNFreeProcs ?

Alvaro Herrera <alvherre@surnet.cl> writes:

I just noticed the HaveNFreeProcs routine is coded as a loop around the
ProcGlobal struct members. I wonder if it's possible to use a simple
check in procArray->numBackends against procArray->maxBackends instead?

It used to look like that, but now that numBackends includes prepared
transactions that's no longer a useful test. I think that the existing
coding is OK, because it's written to not loop more than
superuser_reserved_connections times, and it's hard to imagine anyone
would set that to more than half a dozen or so.

Also, that routine will disappear entirely if we agree to remove
commit_siblings (see nearby thread), so right at the moment I'm not very
concerned about improving it. If it is still there forty-eight hours
from now, let's talk about it then.

regards, tom lane

I wrote:

Also, that routine will disappear entirely if we agree to remove
commit_siblings (see nearby thread), so right at the moment I'm not very
concerned about improving it. If it is still there forty-eight hours
from now, let's talk about it then.

Oh, never mind that, I was momentarily confusing it with
CountActiveBackends. But the other point stands.

regards, tom lane

I wrote:

... because it's written to not loop more than
superuser_reserved_connections times, and it's hard to imagine anyone
would set that to more than half a dozen or so.

We could help keep people on the correct path if guc.c enforced a sane
upper limit on superuser_reserved_connections. I'm thinking somewhere
around 10.

Any thoughts about that?

regards, tom lane

On Thu, Jun 23, 2005 at 12:44:25AM -0400, Tom Lane wrote:

I wrote:

... because it's written to not loop more than
superuser_reserved_connections times, and it's hard to imagine anyone
would set that to more than half a dozen or so.

We could help keep people on the correct path if guc.c enforced a sane
upper limit on superuser_reserved_connections. I'm thinking somewhere
around 10.

Any thoughts about that?

Maybe a warning in the docs and the sample/default config file would be
better. It seems silly to limit this just because it might cause a
performance problem (this is just a performance issue, right?)
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