Re: Excessive PostmasterIsAlive calls slow down WAL redo

On April 9, 2018 6:57:23 PM PDT, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
>Andres Freund wrote:
>>
>> On April 9, 2018 6:31:07 PM PDT, Alvaro Herrera
><alvherre(at)alvh(dot)no-ip(dot)org> wrote:
>
>> >Would it work to use this second pipe, to which each child writes a
>> >byte that postmaster never reads, and then rely on SIGPIPE when
>> >postmaster dies? Then we never need to do a syscall.
>>
>> I'm not following, could you expand on what you're suggesting? Note
>> that you do not get SIGPIPE for already buffered writes. Which
>> syscall can we avoid?
>
>Ah. I was thinking we'd get SIGPIPE from the byte sent at the start,
>as
>soon as the kernel saw that postmaster abandoned the fd by dying.
>Scratch that then.

Had the same idea, but unfortunately reality, in the form of a test program, cured me of my hope ;)
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