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Remove unnecessary dependency on statement_timeout in prepared_xacts test.

Browse Source 
Rather than waiting around for statement_timeout to expire, we can just
try to take the table's lock in nowait mode.  This saves some fraction
under 4 seconds when running this test with prepared xacts available,
and it guards against timeout-expired-anyway failures on very slow
machines when prepared xacts are not available, as seen in a recent
failure on axolotl for instance.

This approach could fail if autovacuum were to take an exclusive lock
on the test table concurrently, but there's no reason for it to do so.

Since the main point here is to improve stability in the buildfarm,
back-patch to all supported branches.
This commit is contained in:
Tom Lane
2017-03-13 16:46:32 -04:00
parent f08a90ecd2
commit 033dcdcd8a
3 changed files with 8 additions and 22 deletions
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10
src/test/regress/expected/prepared_xacts.out
View File

@ -195,9 +195,8 @@ SELECT gid FROM pg_prepared_xacts;
-- pxtest3 should be locked because of the pending DROP -- pxtest3 should be locked because of the pending DROP
begin; begin;
set statement_timeout to 2000; lock table pxtest3 in access share mode nowait;
SELECT * FROM pxtest3; ERROR: could not obtain lock on relation "pxtest3"
ERROR: canceling statement due to statement timeout
rollback; rollback;
-- Disconnect, we will continue testing in a different backend -- Disconnect, we will continue testing in a different backend
\c - \c -
@ -211,9 +210,8 @@ SELECT gid FROM pg_prepared_xacts;
-- pxtest3 should still be locked because of the pending DROP -- pxtest3 should still be locked because of the pending DROP
begin; begin;
set statement_timeout to 2000; lock table pxtest3 in access share mode nowait;
SELECT * FROM pxtest3; ERROR: could not obtain lock on relation "pxtest3"
ERROR: canceling statement due to statement timeout
rollback; rollback;
-- Commit table creation -- Commit table creation
COMMIT PREPARED 'regress-one'; COMMIT PREPARED 'regress-one';

14
src/test/regress/expected/prepared_xacts_1.out
View File

@ -199,12 +199,7 @@ SELECT gid FROM pg_prepared_xacts;
-- pxtest3 should be locked because of the pending DROP -- pxtest3 should be locked because of the pending DROP
begin; begin;
set statement_timeout to 2000; lock table pxtest3 in access share mode nowait;
SELECT * FROM pxtest3;
fff
-----
(0 rows)
rollback; rollback;
-- Disconnect, we will continue testing in a different backend -- Disconnect, we will continue testing in a different backend
\c - \c -
@ -216,12 +211,7 @@ SELECT gid FROM pg_prepared_xacts;
-- pxtest3 should still be locked because of the pending DROP -- pxtest3 should still be locked because of the pending DROP
begin; begin;
set statement_timeout to 2000; lock table pxtest3 in access share mode nowait;
SELECT * FROM pxtest3;
fff
-----
(0 rows)
rollback; rollback;
-- Commit table creation -- Commit table creation
COMMIT PREPARED 'regress-one'; COMMIT PREPARED 'regress-one';

6
src/test/regress/sql/prepared_xacts.sql
View File

@ -123,8 +123,7 @@ SELECT gid FROM pg_prepared_xacts;
-- pxtest3 should be locked because of the pending DROP -- pxtest3 should be locked because of the pending DROP
begin; begin;
set statement_timeout to 2000; lock table pxtest3 in access share mode nowait;
SELECT * FROM pxtest3;
rollback; rollback;
-- Disconnect, we will continue testing in a different backend -- Disconnect, we will continue testing in a different backend
@ -135,8 +134,7 @@ SELECT gid FROM pg_prepared_xacts;
-- pxtest3 should still be locked because of the pending DROP -- pxtest3 should still be locked because of the pending DROP
begin; begin;
set statement_timeout to 2000; lock table pxtest3 in access share mode nowait;
SELECT * FROM pxtest3;
rollback; rollback;
-- Commit table creation -- Commit table creation