Horton

Re: Decoding speculative insert with toast leaks memory

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Petr Jelinek <petr.jelinek@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Tomas Vondra <tomas.vondra@enterprisedb.com>
Date: 2021-06-07T13:04:34Z
Lists: pgsql-hackers 
On Mon, Jun 7, 2021 at 6:04 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> I have fixed all pending review comments and also added a test case which is working fine.
>

Few observations and questions on testcase:
1.
+step "s1_lock_s2" { SELECT pg_advisory_lock(2); }
+step "s1_lock_s3" { SELECT pg_advisory_lock(2); }
+step "s1_session" { SET spec.session = 1; }
+step "s1_begin" { BEGIN; }
+step "s1_insert_tbl1" { INSERT INTO tbl1 VALUES(1, repeat('a', 4000))
ON CONFLICT DO NOTHING; }
+step "s1_abort" { ROLLBACK; }
+step "s1_unlock_s2" { SELECT pg_advisory_unlock(2); }
+step "s1_unlock_s3" { SELECT pg_advisory_unlock(2); }

Here, s1_lock_s3 and s1_unlock_s3 uses 2 as identifier. Don't you need
to use 3 in that part of the test?

2. In the test, there seems to be an assumption that we can unlock s2
and s3 one after another, and then both will start waiting on s-1 but
isn't it possible that before s2 start waiting on s1, s3 completes its
insertion and then s2 will never proceed for speculative insertion?

>  I haven't yet checked on the back branches.  Let's discuss if we think this patch looks fine then I can apply and test on the back branches.
>

Sure, that makes sense.

-- 
With Regards,
Amit Kapila.

Commits

  1. Fix ABI break introduced by commit 4daa140a2f.

  2. Fix valgrind issue in pgoutput.c.

  3. Fix decoding of speculative aborts.

  4. pgoutput: Fix memory leak due to RelationSyncEntry.map.

  5. Fix initialization of RelationSyncEntry for streaming transactions.

  6. Implement streaming mode in ReorderBuffer.