Horton

Re: Reducing the chunk header sizes on all memory context types

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Julien Rouhaud <rjuju123@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2022-09-20T05:23:15Z
Lists: pgsql-hackers 
David Rowley <dgrowleyml@gmail.com> writes:
> On Tue, 20 Sept 2022 at 13:23, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> ... but I'm completely not satisfied with the current
>> situation in HEAD.

> Maybe you've forgotten that MemoryContextContains() is broken in the
> back branches or just don't think it is broken?

"Broken" is a strong claim.  There's reason to think it could fail
in the back branches, but little evidence that it actually has failed
in the field.  So yeah, we have work to do --- which is the exact
opposite of your apparent stand that we can walk away from the
problem.

			regards, tom lane

Commits

  1. Harden memory context allocators against bogus chunk pointers.

  2. Improve our ability to detect bogus pointers passed to pfree et al.

  3. Remove MemoryContextContains().

  4. Remove uses of MemoryContextContains in nodeAgg.c and nodeWindowAgg.c.

  5. Temporarily make MemoryContextContains return false

  6. Make MemoryContextContains work correctly again

  7. Make more effort to put a sentinel at the end of allocated memory

  8. Fix some possibly latent bugs in slab.c

  9. Various cleanups of the new memory context header code

  10. Revert "Add missing padding from MemoryChunk struct"

  11. Use MAXALIGN() in calculations using sizeof(SlabBlock)

  12. Add missing padding from MemoryChunk struct

  13. Improve performance of and reduce overheads of memory management