Re: Connections hang indefinitely while taking a gin index's LWLock buffer_content lock

Hi!

> 13 дек. 2018 г., в 17:03, Alexander Korotkov <aekorotkov(at)gmail(dot)com> написал(а):
>
> Thank you. I've revised your patch and pushed it. As long as two
> other patches in this thread.

That's great! Thanks!

> 13 дек. 2018 г., в 20:12, chjischj(at)163(dot)com написал(а):
>
>
> hi
> I Have a question. Why the order of unlocking is not adjusted in this patch? like this:
>
> if (BufferIsValid(lbuffer))
> UnlockReleaseBuffer(lbuffer);
> if (BufferIsValid(pbuffer))
> UnlockReleaseBuffer(pbuffer);
> if (BufferIsValid(dbuffer))
> UnlockReleaseBuffer(dbuffer);
> ==>
> if (BufferIsValid(pbuffer))
> UnlockReleaseBuffer(pbuffer);
> if (BufferIsValid(dbuffer))
> UnlockReleaseBuffer(dbuffer);
> if (BufferIsValid(lbuffer))
> UnlockReleaseBuffer(lbuffer);

I think that unlock order does not matter. But I may be wrong. May be just for uniformity?

> 13 дек. 2018 г., в 21:48, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> написал(а):
>
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
>> I am seeing this warning in the 9.4 branch:
>> ginxlog.c:756:5: warning: ‘lbuffer’ may be used uninitialized
>> in this function [-Wmaybe-uninitialized]
>
> I'm also getting that, just in 9.4, but at a different line number:
>
> ginxlog.c: In function 'ginRedoDeletePage':
> ginxlog.c:693: warning: 'lbuffer' may be used uninitialized in this function
>
> That's with gcc version 4.4.7 20120313 (Red Hat 4.4.7-23)

That's the same variable, one place is definition while other is potential misuse.
Seems like these 2 lines [0]

+ if (BufferIsValid(lbuffer))
+ UnlockReleaseBuffer(lbuffer);

are superfluous: lbuffer is UnlockReleased earlier.

Best regards, Andrey Borodin.

[0] https://github.com/postgres/postgres/commit/19cf52e6cc33b9e126775f28269ccccb6ddf7e30#diff-ed6446a8993c76d2884ec6413e49a6b6R757