Re: Fresh build on OS X not working (memory) - Mailing list pgsql-admin

From Tom Lane
Subject Re: Fresh build on OS X not working (memory)
Date
Msg-id 10669.1272754339@sss.pgh.pa.us
Whole thread Raw
In response to Re: Fresh build on OS X not working (memory)  (Gavin Kistner <phrogz@mac.com>)
List pgsql-admin
Gavin Kistner <phrogz@mac.com> writes:
> On Apr 30, 2010, at 3:35 PM, Tom Lane wrote:
>> Does the theory of a pre-existing smaller shmem segment make sense from
>> your end?  In particular, had you previously had another Postgres server
>> running on that machine, and perhaps killed it ungracefully?

> It seems probably that you have hit the nail squarely on the head. I had installed from the one-click (which was
workingwith the memory changes supplied in the README), and IIRC I tried to kill a few processes in preparation for a
manualuninstall before I found the supplied uninstall app. I then compiled and installed from source. When that failed
asdescribed earlier, all changes I made to the settings were (as you guessed) through the sysctl -w option without a
reboot.The first reboot I had was after I replaced my sysctl.conf wholesale with yours, and all was well. 

Yeah, I was able to reproduce the problem locally by kill -9'ing the
postmaster and then enlarging max_connections in postgresql.conf before
trying to restart.  In your case it might've been caused by the new
version needing a bit more shared memory rather than by any change in
parameter settings, but the basic issue seems pretty clear now.

I've applied a patch to our CVS to make PG behave more sanely in this
case.  It does do the right thing if it recognizes that the shmget
failure is due to a pre-existing segment, but we weren't being
sufficiently careful about distinguishing that from a bad size request.

Thanks for the report!

            regards, tom lane

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