Horton

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

Tom Lane <tgl@sss.pgh.pa.us>

View thread View on postgr.es
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Noah Misch <noah@leadboat.com>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Stephen Frost <sfrost@snowman.net>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-04-28T02:06:52Z
Lists: pgsql-hackers 
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

Commits

  1. Avoid "could not reattach" by providing space for concurrent allocation.

  2. Assert that pgwin32_signal_initialize() has been called early enough.

  3. Remove investigative code for can't-reattach-to-shared-memory errors.

  4. Does it help to wait before reattaching?

  5. Map and unmap the shared memory block before risking VirtualFree.

  6. Further effort at preventing memory map dump from affecting the results.

  7. Remove Windows module-list-dumping code.

  8. Dump full memory maps around failing Windows reattach code.

  9. Get still more info about Windows can't-reattach-to-shared-memory errors.

  10. Get more info about Windows can't-reattach-to-shared-memory errors.

  11. Try to get some info about Windows can't-reattach-to-shared-memory errors.