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Fix for bug #26380: LOCK TABLES + FLUSH LOGS causes deadlock

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The log tables are by nature PERFORMANCE_SCHEMA tables,
which should not be affected by SET GLOBAL READ_ONLY or FLUSH TABLES
WITH READ LOCK.

The implementation of FLUSH TABLES WITH READ LOCK already ignored log tables.
Now with this patch, the implementation of LOCK TABLE also ignore a
global read lock for log tables, which was the missing symmetry.
This commit is contained in:
ramil/ram@mysql.com/ramil.myoffice.izhnet.ru
2007-06-17 09:56:33 +05:00
parent e0adab8ce7
commit f47b82906d
5 changed files with 54 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
mysql-test/r/flush.result
View File

@ -55,3 +55,19 @@ flush tables with read lock;
insert into t2 values(1);
unlock tables;
drop table t1, t2;
End of 5.0 tests
set @old_general_log= @@general_log;
set @old_read_only= @@read_only;
set global general_log= on;
flush tables with read lock;
flush logs;
unlock tables;
set global read_only=1;
flush logs;
unlock tables;
flush tables with read lock;
flush logs;
unlock tables;
set global general_log= @old_general_log;
set global read_only= @old_read_only;
End of 5.1 tests

26
mysql-test/t/flush.test
View File

@ -133,4 +133,28 @@ disconnect con3;
connection default;
drop table t1, t2;
# End of 5.0 tests
--echo End of 5.0 tests
#
# Bug #26380: LOCK TABLES + FLUSH LOGS causes deadlock
#
set @old_general_log= @@general_log;
set @old_read_only= @@read_only;
set global general_log= on;
flush tables with read lock;
flush logs;
unlock tables;
set global read_only=1;
flush logs;
unlock tables;
flush tables with read lock;
flush logs;
unlock tables;
set global general_log= @old_general_log;
set global read_only= @old_read_only;
--echo End of 5.1 tests

4
sql/lock.cc
View File

@ -707,9 +707,7 @@ static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table_ptr, uint count,
if (!table_ptr[i]-> file->
check_if_locking_is_allowed(thd->lex->sql_command, thd->lex->type,
table_ptr[i], count, i, &system_count,
(thd == logger.get_general_log_thd()) ||
(thd == logger.get_slow_log_thd()) ||
(thd == logger.get_privileged_thread())))
logger.is_privileged_thread(thd)))
DBUG_RETURN(0);
}

6
sql/log.h
View File

@ -600,6 +600,12 @@ public:
else
return NULL;
}
bool is_privileged_thread(THD *thd)
{
return thd == get_general_log_thd() ||
thd == get_slow_log_thd() ||
thd == get_privileged_thread();
}
};
enum enum_binlog_format {

8
sql/sql_base.cc
View File

@ -4018,6 +4018,11 @@ int lock_tables(THD *thd, TABLE_LIST *tables, uint count, bool *need_reopen)
{
DBUG_ASSERT(thd->lock == 0); // You must lock everything at once
TABLE **start,**ptr;
uint lock_flag= MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN;
/* Don't honor the GLOBAL READ LOCK if called from a logger */
if (logger.is_privileged_thread(thd))
lock_flag|= MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK;
if (!(ptr=start=(TABLE**) thd->alloc(sizeof(TABLE*)*count)))
DBUG_RETURN(-1);
@ -4046,8 +4051,7 @@ int lock_tables(THD *thd, TABLE_LIST *tables, uint count, bool *need_reopen)
}
if (! (thd->lock= mysql_lock_tables(thd, start, (uint) (ptr - start),
MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN,
need_reopen)))
lock_flag, need_reopen)))
{
if (thd->lex->requires_prelocking())
{