Horton

Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Noah Misch <noah@leadboat.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>, Erik Rijkers <er@xs4all.nl>, Jeff Janes <jeff.janes@gmail.com>, Kuntal Ghosh <kuntalghosh.2007@gmail.com>, Michael Paquier <michael@paquier.xyz>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Tomas Vondra <tomas.vondra@2ndquadrant.com>
Date: 2020-12-09T10:00:37Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Tighten the concurrent abort check during decoding.

  2. Improve hash_create()'s API for some added robustness.

  3. Use HASH_BLOBS for xidhash.

  4. Fix initialization of RelationSyncEntry for streaming transactions.

  5. Remove unused function declaration in logicalproto.h.

  6. Add additional tests to test streaming of in-progress transactions.

  7. Fix inline marking introduced in commit 464824323e.

  8. Add support for streaming to built-in logical replication.

  9. Fix the SharedFileSetUnregister API.

  10. Fix comment in procarray.c

  11. Suppress compiler warning in non-cassert builds.

  12. Extend the BufFile interface.

  13. Mark a few logical decoding related variables with PGDLLIMPORT.

  14. Implement streaming mode in ReorderBuffer.

  15. Extend the logical decoding output plugin API with stream methods.

  16. WAL Log invalidations at command end with wal_level=logical.

  17. Immediately WAL-log subtransaction and top-level XID association.

  18. Allow logical replication to transfer data in binary format.

  19. Only superuser can set sslcert/sslkey in postgres_fdw user mappings

  20. Track statistics for spilling of changes from ReorderBuffer.

  21. Add logical_decoding_work_mem to limit ReorderBuffer memory usage.

  22. logical decoding: process ASSIGNMENT during snapshot build

  23. Emit invalidations to standby for transactions without xid.

On Wed, Dec 9, 2020 at 2:56 PM Noah Misch <noah@leadboat.com> wrote:
>
> Further testing showed it was a file location problem, not a deletion problem.
> The worker tried to open
> base/pgsql_tmp/pgsql_tmp9896408.1.sharedfileset/16393-510.changes.0, but these
> were the files actually existing:
>
> [nm@power-aix 0:2 2020-12-08T13:56:35 64gcc 0]$ ls -la $(find src/test/subscription/tmp_check -name '*sharedfileset*')
> src/test/subscription/tmp_check/t_015_stream_subscriber_data/pgdata/base/pgsql_tmp/pgsql_tmp9896408.0.sharedfileset:
> total 408
> drwx------    2 nm       usr             256 Dec 08 03:20 .
> drwx------    4 nm       usr             256 Dec 08 03:20 ..
> -rw-------    1 nm       usr          207806 Dec 08 03:20 16393-510.changes.0
>
> src/test/subscription/tmp_check/t_015_stream_subscriber_data/pgdata/base/pgsql_tmp/pgsql_tmp9896408.1.sharedfileset:
> total 0
> drwx------    2 nm       usr             256 Dec 08 03:20 .
> drwx------    4 nm       usr             256 Dec 08 03:20 ..
> -rw-------    1 nm       usr               0 Dec 08 03:20 16393-511.changes.0
>
> > > I have executed "make check" in the loop with only this file.  I have
> > > repeated it 5000 times but no failure, I am wondering shall we try to
> > > execute in the same machine in a loop where it failed once?
> >
> > Yes, that might help. Noah, would it be possible for you to try that
>
> The problem is xidhash using strcmp() to compare keys; it needs memcmp().  For
> this to matter, xidhash must contain more than one element.  Existing tests
> rarely exercise the multi-element scenario.  Under heavy load, on this system,
> the test publisher can have two active transactions at once, in which case it
> does exercise multi-element xidhash.  (The publisher is sensitive to timing,
> but the subscriber is not; once WAL contains interleaved records of two XIDs,
> the subscriber fails every time.)  This would be much harder to reproduce on a
> little-endian system, where strcmp(&xid, &xid_plus_one)!=0.  On big-endian,
> every small XID has zero in the first octet; they all look like empty strings.
>

Your analysis is correct.

> The attached patch has the one-line fix and some test suite changes that make
> this reproduce frequently on any big-endian system.  I'm currently planning to
> drop the test suite changes from the commit, but I could keep them if folks
> like them.  (They'd need more comments and timeout handling.)
>

I think it is better to keep this test which can always test multiple
streams on the subscriber.

Thanks for working on this.

-- 
With Regards,
Amit Kapila.