Re: Is the unfair lwlock behavior intended? - Mailing list pgsql-hackers

From Ants Aasma
Subject Re: Is the unfair lwlock behavior intended?
Date
Msg-id CA+CSw_uCLbNCRPYU12OmCj_8Ghc9Mv-Qy5uyR36TaDLb94L1Zg@mail.gmail.com
Whole thread Raw
In response to Is the unfair lwlock behavior intended?  ("Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>)
Responses Re: Is the unfair lwlock behavior intended?  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Tue, May 24, 2016 at 9:03 AM, Tsunakawa, Takayuki
<tsunakawa.takay@jp.fujitsu.com> wrote:
> I encountered a strange behavior of lightweight lock in PostgreSQL 9.2.  That appears to apply to 9.6, too, as far as
Iexamine the code.  Could you tell me if the behavior is intended or needs fix?
 
>
> Simply put, the unfair behavior is that waiters for exclusive mode are overtaken by share-mode lockers who arrive
later.

9.5 had significant LWLock scalability improvements. This might
improve performance enough so that exclusive lockers don't get
completely starved. It would be helpful if you could test if it's
still possible to trigger starvation with the new code.

Regards,
Ants Aasma



pgsql-hackers by date:

Previous
From: Ants Aasma
Date:
Subject: Re: Is the unfair lwlock behavior intended?
Next
From: David Fetter
Date:
Subject: Re: Allow COPY to use parameters