I noticed this failure report:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=dangomushi&dt=2017-03-29%2019%3A45%3A27

in which we find

*** 
/home/buildfarm/data/buildroot/HEAD/pgsql.build/src/test/regress/expected/updatable_views.out
       Thu Mar 30 04:45:43 2017
--- 
/home/buildfarm/data/buildroot/HEAD/pgsql.build/src/test/regress/results/updatable_views.out
        Thu Mar 30 05:32:37 2017
***************
*** 349,354 ****
--- 349,358 ----
  DROP VIEW ro_view10, ro_view12, ro_view18;
  DROP SEQUENCE seq CASCADE;
  NOTICE:  drop cascades to view ro_view19
+ ERROR:  deadlock detected
+ DETAIL:  Process 7576 waits for AccessShareLock on relation 1259 of database 
16384; blocked by process 7577.
+ Process 7577 waits for ShareRowExclusiveLock on relation 6102 of database 
16384; blocked by process 7576.
+ HINT:  See server log for query details.
  -- simple updatable view
  CREATE TABLE base_tbl (a int PRIMARY KEY, b text DEFAULT 'Unspecified');
  INSERT INTO base_tbl SELECT i, 'Row ' || i FROM generate_series(-2, 2) g(i);

and the referenced bit of log is

[58dc19dd.1d98:175] ERROR:  deadlock detected
[58dc19dd.1d98:176] DETAIL:  Process 7576 waits for AccessShareLock on relation 
1259 of database 16384; blocked by process 7577.
        Process 7577 waits for ShareRowExclusiveLock on relation 6102 of 
database 16384; blocked by process 7576.
        Process 7576: DROP SEQUENCE seq CASCADE;
        Process 7577: VACUUM FULL pg_class;
[58dc19dd.1d98:177] HINT:  See server log for query details.
[58dc19dd.1d98:178] STATEMENT:  DROP SEQUENCE seq CASCADE;

Of course, 1259 is pg_class and 6102 is pg_subscription_rel.

I await with interest an explanation of what "VACUUM FULL pg_class" is
doing trying to acquire ShareRowExclusiveLock on pg_subscription_rel, not
to mention why a DROP SEQUENCE is holding some fairly strong lock on that
relation.  *Especially* in a situation where no subscriptions exist ---
but even if any did, this seems unacceptable on its face.  Access to core
catalogs like pg_class cannot depend on random other stuff.

                        regards, tom lane


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers

Reply via email to