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This deadlock happened if DROP DATABASE was blocked due to an open HANDLER table from a different connection. While DROP DATABASE is blocked, it holds the LOCK_mysql_create_db mutex. This results in a deadlock if the connection with the open HANDLER table tries to execute a CREATE/ALTER/DROP DATABASE statement as they all try to acquire LOCK_mysql_create_db. This patch makes this deadlock scenario very unlikely by closing and marking for re-open all HANDLER tables for which there are pending conflicing locks, before LOCK_mysql_create_db is acquired. However, there is still a very slight possibility that a connection could access one of these HANDLER tables between closing/marking for re-open and the acquisition of LOCK_mysql_create_db. This patch is for 5.1 only, a separate and complete fix will be made for 5.5+. Test case added to schema.test.
51 lines
1.3 KiB
Plaintext
51 lines
1.3 KiB
Plaintext
drop database if exists mysqltest1;
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create schema foo;
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show create schema foo;
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Database Create Database
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foo CREATE DATABASE `foo` /*!40100 DEFAULT CHARACTER SET latin1 */
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show schemas;
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Database
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information_schema
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foo
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mtr
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mysql
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performance_schema
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test
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drop schema foo;
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#
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# Bug #48940 MDL deadlocks against mysql_rm_db
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#
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DROP SCHEMA IF EXISTS schema1;
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# Connection default
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CREATE SCHEMA schema1;
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CREATE TABLE schema1.t1 (a INT);
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SET autocommit= FALSE;
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INSERT INTO schema1.t1 VALUES (1);
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# Connection 2
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DROP SCHEMA schema1;
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# Connection default
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ALTER SCHEMA schema1 DEFAULT CHARACTER SET utf8;
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Got one of the listed errors
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SET autocommit= TRUE;
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# Connection 2
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# Connection default
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#
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# Bug #49988 MDL deadlocks with mysql_create_db, reload_acl_and_cache
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#
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DROP SCHEMA IF EXISTS schema1;
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# Connection default
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CREATE SCHEMA schema1;
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CREATE TABLE schema1.t1 (id INT);
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LOCK TABLE schema1.t1 WRITE;
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# Connection con2
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DROP SCHEMA schema1;
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# Connection default
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# CREATE SCHEMA used to give a deadlock.
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# Now we prohibit CREATE SCHEMA in LOCK TABLES mode.
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CREATE SCHEMA IF NOT EXISTS schema1;
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ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
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# UNLOCK TABLES so DROP SCHEMA can continue.
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UNLOCK TABLES;
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# Connection con2
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# Connection default
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