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Optimize flush tables with read lock (FTWRL) to not wait for select's

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Part of MDEV-5336 Implement LOCK FOR BACKUP

The idea is that instead of waiting in close_cached_tables() for all
tables to be closed, we instead call flush_tables() that does:
- Flush not used objects in table cache to free memory
- Collect all tables that are open
- Call HA_EXTRA_FLUSH on the objects, to get them into "closed state"
- Added HA_EXTRA_FLUSH support to archive and CSV
- Added multi-user protection to HA_EXTRA_FLUSH in MyISAM and Aria

The benefit compared to old code is:
- FTWRL doesn't have to wait for long running read operations or
  open HANDLER's
This commit is contained in:
Monty
2018-10-09 18:55:18 +03:00
parent 306b7a2243
commit 163b34fe25
35 changed files with 456 additions and 81 deletions
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50
mysql-test/main/flush_read_lock.test
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@ -800,6 +800,8 @@ connection default;
--echo # 14.2) FLUSH TABLES <list> WITH READ LOCK is not blocked by
--echo # active FTWRL. But since the latter keeps tables open
--echo # FTWRL is blocked by FLUSH TABLES <list> WITH READ LOCK.
--echo # Fixed by MDEV-5336
flush tables with read lock;
--echo # FT <list> WRL is allowed under FTWRL at the moment.
--echo # It does not make much sense though.
@ -815,19 +817,10 @@ unlock tables;
connection default;
flush tables t1_base, t2_base with read lock;
connection $con_aux1;
--send flush tables with read lock
connection $con_aux2;
--echo # Wait until FTWRL is blocked.
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = "Waiting for table flush" and
info = "flush tables with read lock";
--source include/wait_condition.inc
flush tables with read lock;
connection default;
unlock tables;
connection $con_aux1;
--echo # Reap FTWRL.
--reap
unlock tables;
connection default;
@ -2022,3 +2015,40 @@ set global sql_mode=default;
# Check that all connections opened by test cases in this file are really
# gone so execution of other tests won't be affected by their presence.
--source include/wait_until_count_sessions.inc
--echo #
--echo # Deadlock between FTWRL under open handler and DDL/LOCK TABLES
--echo #
CREATE TABLE t1(a INT);
HANDLER t1 OPEN;
--echo #
connect (con1,localhost,root,,);
SET DEBUG_SYNC= 'mdl_acquire_lock_wait SIGNAL ready';
--send LOCK TABLE t1 WRITE
--echo #
--echo # we need to do it in a separate connection,
--echo # because SET DEBUG_SYNC call open_tables()/mysql_ha_flush() :(
connect (con2,localhost,root,,);
SET DEBUG_SYNC= 'now WAIT_FOR ready';
disconnect con2;
--echo #
connection default;
--send FLUSH TABLES WITH READ LOCK
--echo #
connection con1;
reap;
UNLOCK TABLES;
disconnect con1;
--echo #
connection default;
reap;
UNLOCK TABLES;
HANDLER t1 CLOSE;
DROP TABLE t1;
SET DEBUG_SYNC= 'RESET';