[pgpool-general: 1207] Re: Semphore errors after adding/removing hosts?

[Lonni J Friedman]

I've seen this behavior as well (after dettaching & reattaching nodes)
with 3.2.1.  However, when I experienced it, it was after dettaching
all the nodes at the same time, which I was later told was not
supported without restarting the master pgpool daemon.

How many nodes do you total ,and how many were active at any given time?

On Fri, Nov 30, 2012 at 4:41 PM, Nick Webb <nickw at redwireservices.com> wrote:
> Hello,
>
> I'm fairly new to pgpool, but am already quite a fan, thanks for the great
> software!
>
> When using the pcp_detach_node command followed by pcp_attach_node after
> doing some maintenance on a backend, I start getting errors like this in the
> log:
>
> Nov 27 03:09:02 PGLB pgpool-X[32282]: semop(id=884737) failed: Invalid
> argument
> Nov 27 03:09:02 PGLB pgpool-X[10230]: semop(id=884737) failed: Invalid
> argument
> Nov 27 03:09:02 PGLB pgpool-X[10230]: semop(id=884737) failed: Invalid
> argument
>
> These continue over and over until the process is restarted.
>
> I ignored them when I first saw it, as it seemed to function just fine, but
> a few days later our application could not connect to PGPool very well, it
> was very slow and most connections timed out despite the system load and CPU
> being very low.  Connections from the PGPool host to the back-ends directly
> were also very quick (via psql command).
>
> Stopping and starting PGPool immediately returned the service to normal
> performance levels.
>
> Are these two issues linked?  How can I stop from getting the semop error
> when attaching hosts?
>
> It also seems that about every 3rd or 4th pcp_ command I run hangs,
> seemingly waiting until open connections finish... and I think it finish
> after a few minutes.  This may be related, as I seem to recall one of these
> "hangs" when adding the backend back to the pool, then seeing the semop
> errors (could have been the detach that hung, not sure).