Re: Call lazy_check_wraparound_failsafe earlier for parallel vacuum

>    I adjusted the FAILSAFE_EVERY_PAGES comments, which now point out that
>    FAILSAFE_EVERY_PAGES is a power-of-two. The implication is that the
>    compiler is all but guaranteed to be able to reduce the modulo
>    division into a shift in the lazy_scan_heap loop, at the point of the
>    failsafe check. I doubt that it would really matter if the compiler
>    had to generate a DIV instruction, but it seems like a good idea to
>    avoid it on general principle, at least in performance sensitive code.

Thank you! 

Regards,

Sami Imseih
Amazon Web Services (AWS)