Re: [HACKERS] Re: Reducing sema usage (was Postmaster dies with many child processes)
От | Bruce Momjian |
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Тема | Re: [HACKERS] Re: Reducing sema usage (was Postmaster dies with many child processes) |
Дата | |
Msg-id | 199901310145.UAA01565@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: Reducing sema usage (was Postmaster dies with many child processes) (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: [HACKERS] Re: Reducing sema usage (was Postmaster dies with many child processes)
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Список | pgsql-hackers |
> I said: > > Any thoughts about which way to jump? I'm sort of inclined to take > > the simpler approach myself... > > A further thought: we could leave the semaphore management as-is, > and instead try to make running out of semaphores a less catastrophic > failure. I'm thinking that the postmaster could be the one to try > to allocate more semaphores whenever there are none left, just before > trying to fork a new backend. (The postmaster has access to the same > shared memory as the backends, right? So no reason it couldn't do this.) > If the allocation fails, it can simply refuse the connection request, > rather than having to proceed as though we'd had a full-fledged backend > crash. This only works because we can predict the number of semas > needed by an additional backend -- but we can: one. If they asked for 64 backends, we better be able go give them to them, and not crash or fail under a load. 64 semaphores is nothing. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania19026
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