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Bug#32395 Alter table under a impending global read lock causes a server crash

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The problem is that some DDL statements (ALTER TABLE, CREATE
TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to
momentarily drop the lock, reopen the table and grab the write
lock again (using reopen_tables). When grabbing the lock again,
reopen_tables doesn't pass a flag to mysql_lock_tables in
order to ignore the impending global read lock, which causes a
assertion because LOCK_open is being hold. Also dropping the
lock must not signal to any threads that the table has been
relinquished (related to the locking/flushing protocol).

The solution is to correct the way the table is reopenned
and the locks grabbed. When reopening the table and under
LOCK TABLES, the table version should be set to 0 so other
threads have to wait for the table. When grabbing the lock,
any other flush should be ignored because it's theoretically
a atomic operation. The chosen solution also fixes a potential
discrepancy between binlog and GRL (global read lock) because
table placeholders were being ignored, now a FLUSH TABLES WITH
READ LOCK will properly for table with open placeholders.

It's also important to mention that this patch doesn't fix
a potential deadlock if one uses two GRLs under LOCK TABLES
concurrently.


mysql-test/r/lock_multi.result:
  Add test case result for Bug#32395
mysql-test/r/trigger_notembedded.result:
  Add test case result for Bug#32395
mysql-test/t/lock_multi.test:
  Add test case for Bug#32395
mysql-test/t/trigger_notembedded.test:
  Enable test case for Bug#32395
sql/ha_ndbcluster.cc:
  Update close_cached_tables usage.
sql/ha_ndbcluster_binlog.cc:
  Update close_cached_tables usage.
sql/mysql_priv.h:
  Update close_cache_tables prototype.
sql/set_var.cc:
  Update close_cached_tables usage and set flag to wait for
  tables with placeholders. This is one of the places where
  a GRL can be obtained.
sql/sql_base.cc:
  Preserve old version for write locked tables and ignore
  pending flushes and update close_cache_tables to take
  into account name locked tables.
sql/sql_parse.cc:
  Update close_cached_tables usage and pass flag so that
  name locked tables are waited for.
sql/sql_table.cc:
  Protect the table against a impending GRL if under LOCK TABLES.
This commit is contained in:
unknown
2007-12-12 19:44:14 -02:00
parent ede6f50a6a
commit e5a397e28f
11 changed files with 206 additions and 41 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
mysql-test/r/lock_multi.result
View File

@ -113,4 +113,34 @@ handler t1 open;
ERROR HY000: Table storage engine for 't1' doesn't have this option
--> client 1
drop table t1;
drop table if exists t1;
create table t1 (i int);
connection: default
lock tables t1 write;
connection: flush
flush tables with read lock;;
connection: default
alter table t1 add column j int;
connection: insert
insert into t1 values (1,2);;
connection: default
unlock tables;
connection: flush
select * from t1;
i j
unlock tables;
select * from t1;
i j
1 2
drop table t1;
drop table if exists t1;
create table t1 (i int);
connection: default
lock tables t1 write;
connection: flush
flush tables with read lock;;
connection: default
flush tables;
unlock tables;
drop table t1;
End of 5.1 tests

14
mysql-test/r/trigger_notembedded.result
View File

@ -448,4 +448,18 @@ DROP TABLE t1;
DROP DATABASE mysqltest_db1;
USE test;
End of 5.0 tests.
drop table if exists t1;
create table t1 (i int);
connection: default
lock tables t1 write;
connection: flush
flush tables with read lock;;
connection: default
create trigger t1_bi before insert on t1 for each row begin end;
unlock tables;
connection: flush
unlock tables;
select * from t1;
i
drop table t1;
End of 5.1 tests.

98
mysql-test/t/lock_multi.test
View File

@ -150,7 +150,7 @@ send SELECT user.Select_priv FROM user, db WHERE user.user = db.user LIMIT 1;
connection locker;
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = "Locked" and info =
where state = "Waiting for table" and info =
"SELECT user.Select_priv FROM user, db WHERE user.user = db.user LIMIT 1";
--source include/wait_condition.inc
# Make test case independent from earlier grants.
@ -343,4 +343,100 @@ handler t1 open;
connection default;
drop table t1;
#
# Bug#32395 Alter table under a impending global read lock causes a server crash
#
#
# Test ALTER TABLE under LOCK TABLES and FLUSH TABLES WITH READ LOCK
#
--disable_warnings
drop table if exists t1;
--enable_warnings
create table t1 (i int);
connect (flush,localhost,root,,test,,);
connection default;
--echo connection: default
lock tables t1 write;
connection flush;
--echo connection: flush
--send flush tables with read lock;
connection default;
--echo connection: default
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = "Flushing tables";
--source include/wait_condition.inc
alter table t1 add column j int;
connect (insert,localhost,root,,test,,);
connection insert;
--echo connection: insert
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = "Flushing tables";
--source include/wait_condition.inc
--send insert into t1 values (1,2);
--echo connection: default
connection default;
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = "Waiting for release of readlock";
--source include/wait_condition.inc
unlock tables;
connection flush;
--echo connection: flush
--reap
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = "Waiting for release of readlock";
--source include/wait_condition.inc
select * from t1;
unlock tables;
connection insert;
--reap
connection default;
select * from t1;
drop table t1;
disconnect flush;
disconnect insert;
#
# Test that FLUSH TABLES under LOCK TABLES protects write locked tables
# from a impending FLUSH TABLES WITH READ LOCK
#
--disable_warnings
drop table if exists t1;
--enable_warnings
create table t1 (i int);
connect (flush,localhost,root,,test,,);
connection default;
--echo connection: default
lock tables t1 write;
connection flush;
--echo connection: flush
--send flush tables with read lock;
connection default;
--echo connection: default
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = "Flushing tables";
--source include/wait_condition.inc
flush tables;
let $wait_condition=
select count(*) = 1 from information_schema.processlist
where state = "Flushing tables";
--source include/wait_condition.inc
unlock tables;
let $wait_condition=
select count(*) = 0 from information_schema.processlist
where state = "Flushing tables";
--source include/wait_condition.inc
connection flush;
--reap
connection default;
disconnect flush;
drop table t1;
--echo End of 5.1 tests

6
mysql-test/t/trigger_notembedded.test
View File

@ -880,8 +880,9 @@ USE test;
# Bug#23713 LOCK TABLES + CREATE TRIGGER + FLUSH TABLES WITH READ LOCK = deadlock
#
# Test temporarily disable due to Bug#32395
--disable_parsing
--disable_warnings
drop table if exists t1;
--enable_warnings
create table t1 (i int);
connect (flush,localhost,root,,test,,);
connection default;
@ -906,6 +907,5 @@ connection default;
select * from t1;
drop table t1;
disconnect flush;
--enable_parsing
--echo End of 5.1 tests.