Re: [HACKERS] Re: Reducing sema usage (was Postmaster dies with many child processes)

Tom Lane wrote: >Bruce Momjian <maillist@candle.pha.pa.us> writes: >> If they asked for 64 backends, we better be able
gogive them to them, >> and not crash or fail under a load.  64 semaphores is nothing. > >That argument would be pretty
convincingif pre-grabbing the semaphores >was sufficient to ensure we could start N backends, but of course it's >not
sufficient. The system could also run out of processes or file >descriptors, and I doubt that it's reasonable to grab
allof those >instantly at postmaster startup.
 
The major problem at the moment is not that a new backend fails, but
that it brings down everything else with it.  How about having a new
backend set a one-byte flag in shared memory when it has
finished setting itself up? as long as the flag is unset, the
backend is still starting itself up, and a failure will not require
other backends to be brought down.

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver              PGP key from public servers; key
ID32B8FAA1                ========================================    "Jesus saith unto him, I am the way, the truth,
andthe     life; no man cometh unto the Father, but by me."                                     John 14:6