Re: Reviewing freeze map code

On Tue, Jun 21, 2016 at 1:49 PM, Andres Freund <andres@anarazel.de> wrote:
>> I'm also a bit dubious that LockAcquire is safe to call in general
>> with interrupts held.
>
> Looks like we could just acquire the tuple-lock *before* doing the
> toast_insert_or_update/RelationGetBufferForTuple, but after releasing
> the buffer lock. That'd allow us to do avoid doing the nested locking,
> should make the recovery just a goto l2;, ...

Why isn't that racey?  Somebody else can grab the tuple lock after we
release the buffer content lock and before we acquire the tuple lock.

-- 
Robert Haas
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