Re: Backup throttling

Hi,

On 2014-01-15 18:52:32 -0300, Alvaro Herrera wrote:
> Another thing I found a bit strange was the use of the latch.  What this
> patch does is create a separate latch which is used for the throttling.
> This means that if the walsender process receives a signal, it will not
> wake up if it's sleeping in throttling.  Perhaps this is okay: as Andres
> was quoted upthread as saying, maybe this is not a problem because the
> sleep times are typically short anyway.  But we're pretty much used to
> the idea that whenever a signal is sent, processes act on it
> *immediately*.  Maybe some admin will not feel comfortable about waiting
> some extra 20ms when they cancel their base backups.  In any case,
> having a secondary latch to sleep on in a process seems weird.  Maybe
> this should be using MyWalSnd->latch somehow.

Yes, this definitely should reuse MyWalSnd->latch.

slightly related: we should start to reuse procLatch for walsenders
instead of having a separate latch someday.

Greetings,

Andres Freund

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