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

On Tue, Apr 24, 2018 at 11:18 AM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> Greetings,
>
> * Tom Lane (tgl(at)sss(dot)pgh(dot)pa(dot)us) wrote:
>> So far, dory has failed three times with essentially identical symptoms:
>>
>> 2018-04-23 19:57:10.624 GMT [2240] FATAL: could not reattach to shared memory (key=0000000000000190, addr=00000000018E0000): error code 487
>> 2018-04-23 15:57:10.657 EDT [8836] ERROR: lost connection to parallel worker
>> 2018-04-23 15:57:10.657 EDT [8836] STATEMENT: select count(*) from tenk1 group by twenty;
>> 2018-04-23 15:57:10.660 EDT [3820] LOG: background worker "parallel worker" (PID 2240) exited with exit code 1
>>
>> Now how can this be? We've successfully reserved and released the address
>> range we want to use, so it *should* be free at the instant we try to map.
>
> Yeah, that's definitely interesting.

I wondered if another thread with the right timing could map something
between the VirtualFree() and MapViewOfFileEx() calls, but we don't
create the Windows signal handling thread until a bit later. Could
there be any any other threads active in the process?

Maybe try asking what's mapped there with VirtualQueryEx() on failure?

--
Thomas Munro
http://www.enterprisedb.com