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MDEV-7660 - MySQL WL#6671 "Improve scalability by not using thr_lock.c locks

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for InnoDB tables"

Don't use thr_lock.c locks for InnoDB tables. Below is list of changes that
were needed to implement this:
- HANDLER OPEN acquireis MDL_SHARED_READ instead of MDL_SHARED
- HANDLER READ calls external_lock() even if SE is not going to be locked by
  THR_LOCK
- InnoDB lock wait timeouts are now honored which are much shorter by default
  than server lock wait timeouts (1 year vs 50 seconds)
- with @@autocommit= 1 LOCK TABLES disables autocommit implicitely, though
  user still sees @@autocommt= 1
- the above starts implicit transaction
- transactions started by LOCK TABLES are now rolled back on disconnect
  (previously everything was committed due to autocommit)
- transactions started by LOCK TABLES are now rolled back by ROLLBACK
  (previously everything was committed due to autocommit)
- it is now impossible to change BINLOG_FORMAT under LOCK TABLES (at least
  to statement) due to running transaction
- LOCK TABLES WRITE is additionally handled by MDL
- ...in contrast LOCK TABLES READ protection against DML is pure InnoDB
- combining transactional and non-transactional tables under LOCK TABLES
  may cause rolled back changes in transactional table and "committed"
  changes in non-transactional table
- user may disable innodb_table_locks, which will cause LOCK TABLES to be
  noop basically

Removed tests for BUG#45143 and BUG#55930 which cover InnoDB + THR_LOCK. To
operate properly these tests require code flow to go through THR_LOCK debug
sync points, which is not the case after this patch. These tests are removed
by WL#6671 as well. An alternative is to port them to different storage engine.
This commit is contained in:
Sergey Vojtovich
2016-05-06 13:44:07 +04:00
parent e2d6912609
commit d665e79c5b
31 changed files with 151 additions and 1034 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
mysql-test/suite/handler/innodb.result
View File

@ -1299,19 +1299,27 @@ commit;
# an open HANDLER, ER_LOCK_DEADLOCK is reported.
#
create table t1 (a int, key a(a));
create table t2 like t1;
handler t1 open;
connection con1;
lock table t1 write, t2 write;
select get_lock('lock1', 10);
get_lock('lock1', 10)
1
connection default;
drop table t2;
select get_lock('lock1', 10);
connection con2;
# Waiting for 'drop table t2' to get blocked...
# Waiting for 'select get_lock('lock1', 10)' to get blocked...
connection con1;
drop table t1;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
unlock tables;
select release_lock('lock1');
release_lock('lock1')
1
connection default;
get_lock('lock1', 10)
1
select release_lock('lock1');
release_lock('lock1')
1
# Demonstrate that there is no deadlock with FLUSH TABLE,
# even though it is waiting for the other table to go away
create table t2 like t1;
@ -1350,6 +1358,10 @@ handler t1 read a next;
a
1
# Unblock 'lock tables t1 write'.
select * from t1;
a
1
2
commit;
connection con1;
# Reap 'lock tables t1 write'.
@ -1519,10 +1531,6 @@ handler t1 read a last;
a b
7 7
commit;
connection con1;
# Demonstrate that the HANDLER doesn't hold MDL_SHARED_WRITE.
lock table t1 write;
unlock tables;
connection default;
handler t1 read a prev;
a b