RE: Hardwired MAXBACKENDS limit could be history
От | Mikheev, Vadim |
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Тема | RE: Hardwired MAXBACKENDS limit could be history |
Дата | |
Msg-id | 8F4C99C66D04D4118F580090272A7A234D32C2@sectorbase1.sectorbase.com обсуждение исходный текст |
Ответ на | Hardwired MAXBACKENDS limit could be history (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: Hardwired MAXBACKENDS limit could be history
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Список | pgsql-hackers |
> > Did you ever consider remove per-backend semaphores at all? > > We use them to sleep waiting for lock (ie when someone awake > > us by changing our semaphore) - why don't use sigpause and > > some signal? > > That'll fail if the signal arrives before the sigpause(), no? Ops, you're right. > > Semaphores are good to sync access to *shared* > > resources but it's not that case here. > > The thing we really need here is that the right thing has to happen > if the V() occurs before our P(), ie, the V() has to be remembered > so that we will fall through the P() without blocking. > > What I'd like to look at sometime soon is using POSIX semaphores > instead of SysV semaphores. But we need stateful semaphores, > not signals. Conditional variables seem to be more portable - recently I had to rewrite some program with POSIX sem developed under Solaris when porting to AIX. (BTW, OmniORB uses cond vars to simulate semaphores). Vadim
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