Re: "could not reattach to shared memory" on buildfarm member dory

Noah Misch <noah@leadboat.com> writes:
> On Tue, Apr 24, 2018 at 11:37:33AM +1200, Thomas Munro wrote:
>> Maybe try asking what's mapped there with VirtualQueryEx() on failure?

> +1.  An implementation of that:
> https://www.postgresql.org/message-id/20170403065106.GA2624300%40tornado.leadboat.com

Not seeing any other work happening here, I pushed a little bit of
quick-hack investigation code.  This is based on noting that
VirtualAllocEx is documented as rounding the allocation up to a page
boundary (4K), but there's nothing specific about whether or how much
CreateFileMapping or MapViewOfFileEx might round up.  The observed
failures could be explained if those guys might eat more virtual
address space for the same request size as VirtualAllocEx does.
This is a stretch, for sure, but given the lack of any other theories
we might as well check it.

            regards, tom lane