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: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>, 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>
Date: 2020-09-14T03:18:32Z
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 Mon, Sep 14, 2020 at 3:08 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Amit Kapila <amit.kapila16@gmail.com> writes:
> > Pushed.
>
> Observe the following reports:
>
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=idiacanthus&dt=2020-09-13%2016%3A54%3A03
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=desmoxytes&dt=2020-09-10%2009%3A08%3A03
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=komodoensis&dt=2020-09-05%2020%3A22%3A02
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=dragonet&dt=2020-09-04%2001%3A52%3A03
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=dragonet&dt=2020-09-03%2020%3A54%3A04
>
> These are all on HEAD, and all within the last ten days, and I see
> nothing comparable in any branch before that.  So it's hard to avoid
> the conclusion that somebody broke something about ten days ago.
>
> None of these animals provided gdb backtraces; but we do have a built-in
> trace from several, and they all look like pgoutput.so is trying to
> list_free() garbage, somewhere inside a relcache invalidation/rebuild
> scenario:
>

Yeah, this is right, and here is some initial analysis. It seems to be
failing in below code:
rel_sync_cache_relation_cb(){ ...list_free(entry->streamed_txns);..}

This list can have elements only in 'streaming' mode (need to enable
'streaming' with Create Subscription command) whereas none of the
tests in 010_truncate.pl is using 'streaming', so this list should be
empty (NULL). The two different assertion failures shown in BF reports
in list_free code are as below:
Assert(list->length > 0);
Assert(list->length <= list->max_length);

It seems to me that this list is not initialized properly when it is
not used or maybe that is true in some special circumstances because
we initialize it in get_rel_sync_entry(). I am not sure if CCI build
is impacting this in some way.

--
With Regards,
Amit Kapila.