On 08/16/2017 04:20 PM, Heikki Linnakangas wrote:
On 05/06/2017 04:57 PM, David Rowley wrote:
Andres mentioned in [2] that it might be worth exploring using
atomics to do the same job. So I went ahead and did that, and came
up with the attached, which is a slight variation on what he
mentioned in the thread.

To keep things a bit more simple, and streamline, I ended up
pulling out the logic for setting the startblock into another
function, which we only call once before the first call to heap_parallelscan_nextpage(). I also ended up changing phs_cblock
and replacing it with a counter that always starts at zero. The
actual block is calculated based on that + the startblock modulo
nblocks. This makes things a good bit more simple for detecting
when we've allocated all the blocks to the workers, and also works
nicely when wrapping back to the start of a relation when we
started somewhere in the middle due to piggybacking with a
synchronous scan.

Looks reasonable. I edited the comments and the variable names a bit,
to my liking, and committed. Thanks!

A couple of 32-bit x86 buildfarm members don't seem to be happy with this. I'll investigate, but if anyone has a clue, I'm all ears...

- Heikki

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