Re: [HACKERS] Re: Max backend limits cleaned up - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] Re: Max backend limits cleaned up
Date
Msg-id 199902221754.MAA04392@candle.pha.pa.us
Whole thread Raw
In response to RE: [HACKERS] Re: Max backend limits cleaned up  ("Daryl W. Dunbar" <daryl@www.com>)
List pgsql-hackers
[Charset iso-8859-1 unsupported, filtering to ASCII...]
> The default to-date has been 64.  The reason you don't see much
> trouble with it is twofold, 1) Linux has a huge default for
> semaphores and shared memory, 2) The old memory model allocated
> semaphores in blocks of 16 up to MaxBackedId (which was hard coded
> to 64).  I did not run into trouble on untuned Solaris until
> postmaster tried to start the 49th backend (semaphores 49-64 when my
> kernel defaulted to 60).
> 
> The new model allocates semaphores and shared memory at startup,
> assuring you won't experience midstream troubles like I did.  It
> does, however allocate to the max or -N setting, which most users
> will probably never reach.
> 
> I'd vote for 32 as the default.

I understand now.  The stuff is preallocated.

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