Ahh, I think I might see it. "Global/PostgreSQL.2437152779" is an odd
DSM handle (as in, the low order bit is set). That means that it's a
"main region" DSM segment, of the type that you get if you set
min_dynamic_shared_memory (commit 84b1c63a). That looks potentially
broken on Windows, because we have this extra NT handle sharing stuff
in dsm_impl_pin_segment(), which can't possibly work and should
probably be gated on !is_main_region_dsm_handle(seg->handle). On
every other OS that function does nothing, which would explain how we
didn't notice for so long.
Maxime, do you have min_dynamic_shared_memory set?
