Re: Review: Extra Daemons / bgworker

Alvaro Herrera wrote:

> One notable thing is that I had to introduce this in the postmaster
> startup sequence:
>
>     /*
>      * process any libraries that should be preloaded at postmaster start
>      */
>     process_shared_preload_libraries();
>
>     /*
>      * If loadable modules have added background workers, MaxBackends needs to
>      * be updated.  Do so now.
>      */
>     // RerunAssignHook("max_connections");
>     if (GetNumShmemAttachedBgworkers() > 0)
>         SetConfigOption("max_connections",
>                         GetConfigOption("max_connections", false, false),
>                         PGC_POSTMASTER, PGC_S_OVERRIDE);
>
> Note the intention here is to re-run the GUC assign hook for
> max_connections (hence the commented out hypothetical call to do so).
> Obviously, having to go through GetConfigOption and SetConfigOption is
> not a nice thing to do; we'll have to add some new entry point to guc.c
> for this to have a nicer interface.

After fooling with guc.c to create such a new entry point, I decided
that it looks too ugly.  guc.c is already complex enough with the API we
have today that I don't want to be seen creating a partially-duplicate
interface, even if it is going to result in simplified processing of
this one place.  If we ever get around to needing another place to
require rerunning a variable's assign_hook we can discuss it; for now it
doesn't seem worth it.

This is only called at postmaster start time, so it's not too
performance-sensitive, hence SetConfigOption( .., GetConfigOption(), ..)
seems acceptable from that POV.

--
Álvaro Herrera                http://www.2ndQuadrant.com/
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