[pgpool-general: 8067] Re: Advise on reserved_connections

[Jon SCHEWE]

> 
> > I've read the documentation on reserved_connections and num_init_children.
> >From what I understand it seems that reserved_connections should always be 0 or 1, there is no point in setting it larger. Is that correct?
> 
> Basically correct. But you may want to set it larger than 1 if the
> num_init_children is large (like over 1000) to keep safe margin of
> available connection slots.
> 
> > Is the general advise to leave reserved_connections at 0 so that clients block or to use 1 so that clients know that there are no more connections?
> 
> I would advise to start with 0. If your system is busy and the
> connection waiting clients is rapidly increasing, then you may want to
> try to set to 1 or higher.

Thank you for the advice. I tried setting reserved_connections to 1 and num_init_children to 128 and I found that many clients received messages about no more client connections. However when I looked at the pgpool processes I didn't see all of them busy. Changing reserved_connections back to 0 and leaving num_init_children at 128 seems to be working without issue and I don't see clients blocked waiting for a connection.
What would cause this behavior?