Re: [RFC] Should we fix postmaster to avoid slow shutdown?
От | Tsunakawa, Takayuki |
---|---|
Тема | Re: [RFC] Should we fix postmaster to avoid slow shutdown? |
Дата | |
Msg-id | 0A3221C70F24FB45833433255569204D1F65677C@G01JPEXMBYT05 обсуждение исходный текст |
Ответ на | Re: [RFC] Should we fix postmaster to avoid slow shutdown? (Robert Haas <robertmhaas@gmail.com>) |
Список | pgsql-hackers |
From: Robert Haas [mailto:robertmhaas@gmail.com] > So there are two questions here: > > 1. Should we try to avoid having the stats collector write a stats file > during an immediate shutdown? The file will be removed anyway during crash > recovery, so writing it is pointless. I think you are right that 9.4's > solution here is not perfect, because of the 5 second delay, and also because > if the stats collector is stuck inside the kernel trying to write to the > OS, it may be in a non-interruptible wait state where even SIGKILL has no > immediate effect. Anyway, it's stupid even from a performance point of > view to waste time writing a file that we're just going to nuke. > > 2. Should we close listen sockets sooner during an immediate shutdown? > I agree with Tom and Peter that this isn't a good idea. People expect > the sockets not to go away until the end - e.g. they use > PQping() to test the server status, or they connect just to see what error > they get - and the fact that a client application could hypothetically > generate such a relentless stream of connection attempts that the dead-end > backends thereby created slow down shutdown is not in my mind a sufficient > reason to change the behavior. > > So I think 001 should proceed and 002 should be rejected. I'm happy with this conclusion, since I think 1 was the cause of slow shutdown, and 2 is just a hypothesis to pursue thecompleteness. And I can understand the concern about PQping(). Regards Takayuki Tsunakawa
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