2001-09-28 07:05:54 +02:00
|
|
|
flush status;
|
|
|
|
|
show status like 'Table_lock%';
|
2001-01-27 04:00:42 +01:00
|
|
|
Variable_name Value
|
WL#3984 (Revise locking of mysql.general_log and mysql.slow_log)
Bug#25422 (Hang with log tables)
Bug 17876 (Truncating mysql.slow_log in a SP after using cursor locks the
thread)
Bug 23044 (Warnings on flush of a log table)
Bug 29129 (Resetting general_log while the GLOBAL READ LOCK is set causes
a deadlock)
Prior to this fix, the server would hang when performing concurrent
ALTER TABLE or TRUNCATE TABLE statements against the LOG TABLES,
which are mysql.general_log and mysql.slow_log.
The root cause traces to the following code:
in sql_base.cc, open_table()
if (table->in_use != thd)
{
/* wait_for_condition will unlock LOCK_open for us */
wait_for_condition(thd, &LOCK_open, &COND_refresh);
}
The problem with this code is that the current implementation of the
LOGGER creates 'fake' THD objects, like
- Log_to_csv_event_handler::general_log_thd
- Log_to_csv_event_handler::slow_log_thd
which are not associated to a real thread running in the server,
so that waiting for these non-existing threads to release table locks
cause the dead lock.
In general, the design of Log_to_csv_event_handler does not fit into the
general architecture of the server, so that the concept of general_log_thd
and slow_log_thd has to be abandoned:
- this implementation does not work with table locking
- it will not work with commands like SHOW PROCESSLIST
- having the log tables always opened does not integrate well with DDL
operations / FLUSH TABLES / SET GLOBAL READ_ONLY
With this patch, the fundamental design of the LOGGER has been changed to:
- always open and close a log table when writing a log
- remove totally the usage of fake THD objects
- clarify how locking of log tables is implemented in general.
See WL#3984 for details related to the new locking design.
Additional changes (misc bugs exposed and fixed):
1)
mysqldump which would ignore some tables in dump_all_tables_in_db(),
but forget to ignore the same in dump_all_views_in_db().
2)
mysqldump would also issue an empty "LOCK TABLE" command when all the tables
to lock are to be ignored (numrows == 0), instead of not issuing the query.
3)
Internal errors handlers could intercept errors but not warnings
(see sql_error.cc).
4)
Implementing a nested call to open tables, for the performance schema tables,
exposed an existing bug in remove_table_from_cache(), which would perform:
in_use->some_tables_deleted=1;
against another thread, without any consideration about thread locking.
This call inside remove_table_from_cache() was not required anyway,
since calling mysql_lock_abort() takes care of aborting -- cleanly -- threads
that might hold a lock on a table.
This line (in_use->some_tables_deleted=1) has been removed.
2007-07-27 08:31:06 +02:00
|
|
|
Table_locks_immediate 1
|
2001-01-27 04:00:42 +01:00
|
|
|
Table_locks_waited 0
|
2006-09-14 01:37:40 +02:00
|
|
|
select * from information_schema.session_status where variable_name like 'Table_lock%';
|
|
|
|
|
VARIABLE_NAME VARIABLE_VALUE
|
WL#3984 (Revise locking of mysql.general_log and mysql.slow_log)
Bug#25422 (Hang with log tables)
Bug 17876 (Truncating mysql.slow_log in a SP after using cursor locks the
thread)
Bug 23044 (Warnings on flush of a log table)
Bug 29129 (Resetting general_log while the GLOBAL READ LOCK is set causes
a deadlock)
Prior to this fix, the server would hang when performing concurrent
ALTER TABLE or TRUNCATE TABLE statements against the LOG TABLES,
which are mysql.general_log and mysql.slow_log.
The root cause traces to the following code:
in sql_base.cc, open_table()
if (table->in_use != thd)
{
/* wait_for_condition will unlock LOCK_open for us */
wait_for_condition(thd, &LOCK_open, &COND_refresh);
}
The problem with this code is that the current implementation of the
LOGGER creates 'fake' THD objects, like
- Log_to_csv_event_handler::general_log_thd
- Log_to_csv_event_handler::slow_log_thd
which are not associated to a real thread running in the server,
so that waiting for these non-existing threads to release table locks
cause the dead lock.
In general, the design of Log_to_csv_event_handler does not fit into the
general architecture of the server, so that the concept of general_log_thd
and slow_log_thd has to be abandoned:
- this implementation does not work with table locking
- it will not work with commands like SHOW PROCESSLIST
- having the log tables always opened does not integrate well with DDL
operations / FLUSH TABLES / SET GLOBAL READ_ONLY
With this patch, the fundamental design of the LOGGER has been changed to:
- always open and close a log table when writing a log
- remove totally the usage of fake THD objects
- clarify how locking of log tables is implemented in general.
See WL#3984 for details related to the new locking design.
Additional changes (misc bugs exposed and fixed):
1)
mysqldump which would ignore some tables in dump_all_tables_in_db(),
but forget to ignore the same in dump_all_views_in_db().
2)
mysqldump would also issue an empty "LOCK TABLE" command when all the tables
to lock are to be ignored (numrows == 0), instead of not issuing the query.
3)
Internal errors handlers could intercept errors but not warnings
(see sql_error.cc).
4)
Implementing a nested call to open tables, for the performance schema tables,
exposed an existing bug in remove_table_from_cache(), which would perform:
in_use->some_tables_deleted=1;
against another thread, without any consideration about thread locking.
This call inside remove_table_from_cache() was not required anyway,
since calling mysql_lock_abort() takes care of aborting -- cleanly -- threads
that might hold a lock on a table.
This line (in_use->some_tables_deleted=1) has been removed.
2007-07-27 08:31:06 +02:00
|
|
|
TABLE_LOCKS_IMMEDIATE 2
|
2007-05-15 09:45:50 +02:00
|
|
|
TABLE_LOCKS_WAITED 0
|
2001-09-28 07:05:54 +02:00
|
|
|
SET SQL_LOG_BIN=0;
|
2007-10-16 10:43:16 +02:00
|
|
|
set @old_general_log = @@global.general_log;
|
|
|
|
|
set global general_log = 'OFF';
|
2001-09-28 07:05:54 +02:00
|
|
|
drop table if exists t1;
|
2003-12-10 05:31:42 +01:00
|
|
|
create table t1(n int) engine=myisam;
|
2001-09-28 07:05:54 +02:00
|
|
|
insert into t1 values(1);
|
|
|
|
|
lock tables t1 read;
|
|
|
|
|
unlock tables;
|
|
|
|
|
lock tables t1 read;
|
|
|
|
|
update t1 set n = 3;
|
|
|
|
|
unlock tables;
|
2007-08-18 10:28:08 +02:00
|
|
|
show status like 'Table_locks_waited';
|
2001-01-27 04:00:42 +01:00
|
|
|
Variable_name Value
|
|
|
|
|
Table_locks_waited 1
|
2001-09-28 07:05:54 +02:00
|
|
|
drop table t1;
|
2007-10-16 10:43:16 +02:00
|
|
|
set global general_log = @old_general_log;
|
2005-09-06 12:00:35 +02:00
|
|
|
select 1;
|
|
|
|
|
1
|
|
|
|
|
1
|
|
|
|
|
show status like 'last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 0.000000
|
2006-06-20 12:20:32 +02:00
|
|
|
create table t1 (a int);
|
|
|
|
|
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
|
|
|
|
|
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
|
|
|
|
|
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
|
|
|
|
|
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
|
|
|
|
|
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
|
|
|
|
|
select * from t1 where a=6;
|
|
|
|
|
a
|
|
|
|
|
6
|
|
|
|
|
6
|
|
|
|
|
6
|
|
|
|
|
6
|
|
|
|
|
6
|
|
|
|
|
show status like 'last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 12.084449
|
|
|
|
|
show status like 'last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 12.084449
|
|
|
|
|
select 1;
|
|
|
|
|
1
|
|
|
|
|
1
|
|
|
|
|
show status like 'last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 0.000000
|
|
|
|
|
drop table t1;
|
2006-04-07 13:30:40 +02:00
|
|
|
FLUSH STATUS;
|
|
|
|
|
SHOW STATUS LIKE 'max_used_connections';
|
|
|
|
|
Variable_name Value
|
2006-07-04 18:44:35 +02:00
|
|
|
Max_used_connections 1
|
2006-09-14 01:37:40 +02:00
|
|
|
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
|
|
|
|
|
VARIABLE_NAME VARIABLE_VALUE
|
2007-05-15 09:45:50 +02:00
|
|
|
MAX_USED_CONNECTIONS 1
|
2006-04-07 13:30:40 +02:00
|
|
|
SET @save_thread_cache_size=@@thread_cache_size;
|
|
|
|
|
SET GLOBAL thread_cache_size=3;
|
|
|
|
|
SHOW STATUS LIKE 'max_used_connections';
|
|
|
|
|
Variable_name Value
|
2006-07-04 18:44:35 +02:00
|
|
|
Max_used_connections 3
|
2006-09-14 01:37:40 +02:00
|
|
|
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
|
|
|
|
|
VARIABLE_NAME VARIABLE_VALUE
|
2007-05-15 09:45:50 +02:00
|
|
|
MAX_USED_CONNECTIONS 3
|
2006-04-07 13:30:40 +02:00
|
|
|
FLUSH STATUS;
|
|
|
|
|
SHOW STATUS LIKE 'max_used_connections';
|
|
|
|
|
Variable_name Value
|
2006-07-04 18:44:35 +02:00
|
|
|
Max_used_connections 2
|
2006-09-14 01:37:40 +02:00
|
|
|
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
|
|
|
|
|
VARIABLE_NAME VARIABLE_VALUE
|
2007-05-15 09:45:50 +02:00
|
|
|
MAX_USED_CONNECTIONS 2
|
2006-04-07 13:30:40 +02:00
|
|
|
SHOW STATUS LIKE 'max_used_connections';
|
|
|
|
|
Variable_name Value
|
2006-07-04 18:44:35 +02:00
|
|
|
Max_used_connections 3
|
2006-09-14 01:37:40 +02:00
|
|
|
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
|
|
|
|
|
VARIABLE_NAME VARIABLE_VALUE
|
2007-05-15 09:45:50 +02:00
|
|
|
MAX_USED_CONNECTIONS 3
|
2006-05-23 12:10:07 +02:00
|
|
|
SHOW STATUS LIKE 'max_used_connections';
|
|
|
|
|
Variable_name Value
|
2006-07-04 18:44:35 +02:00
|
|
|
Max_used_connections 4
|
2006-09-14 01:37:40 +02:00
|
|
|
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
|
|
|
|
|
VARIABLE_NAME VARIABLE_VALUE
|
2007-05-15 09:45:50 +02:00
|
|
|
MAX_USED_CONNECTIONS 4
|
2006-04-07 13:30:40 +02:00
|
|
|
SET GLOBAL thread_cache_size=@save_thread_cache_size;
|
2007-08-28 17:51:03 +02:00
|
|
|
CREATE TABLE t1 ( a INT );
|
|
|
|
|
INSERT INTO t1 VALUES (1), (2);
|
|
|
|
|
SELECT a FROM t1 LIMIT 1;
|
|
|
|
|
a
|
|
|
|
|
1
|
|
|
|
|
SHOW SESSION STATUS LIKE 'Last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 2.402418
|
|
|
|
|
EXPLAIN SELECT a FROM t1;
|
|
|
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
|
|
|
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
|
|
|
|
|
SHOW SESSION STATUS LIKE 'Last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 2.402418
|
|
|
|
|
SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
|
|
|
|
|
a
|
|
|
|
|
1
|
|
|
|
|
2
|
|
|
|
|
SHOW SESSION STATUS LIKE 'Last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 0.000000
|
|
|
|
|
EXPLAIN SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
|
|
|
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
|
|
|
1 PRIMARY t1 ALL NULL NULL NULL NULL 2
|
|
|
|
|
2 UNION t1 ALL NULL NULL NULL NULL 2
|
|
|
|
|
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL Using filesort
|
|
|
|
|
SHOW SESSION STATUS LIKE 'Last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 0.000000
|
|
|
|
|
SELECT a IN (SELECT a FROM t1) FROM t1 LIMIT 1;
|
|
|
|
|
a IN (SELECT a FROM t1)
|
|
|
|
|
1
|
|
|
|
|
SHOW SESSION STATUS LIKE 'Last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 0.000000
|
|
|
|
|
SELECT (SELECT a FROM t1 LIMIT 1) x FROM t1 LIMIT 1;
|
|
|
|
|
x
|
|
|
|
|
1
|
|
|
|
|
SHOW SESSION STATUS LIKE 'Last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 0.000000
|
|
|
|
|
SELECT * FROM t1 a, t1 b LIMIT 1;
|
|
|
|
|
a a
|
|
|
|
|
1 1
|
|
|
|
|
SHOW SESSION STATUS LIKE 'Last_query_cost';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Last_query_cost 4.805836
|
|
|
|
|
DROP TABLE t1;
|
2006-06-20 12:20:32 +02:00
|
|
|
show status like 'com_show_status';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Com_show_status 3
|
|
|
|
|
show status like 'hand%write%';
|
|
|
|
|
Variable_name Value
|
WL#3984 (Revise locking of mysql.general_log and mysql.slow_log)
Bug#25422 (Hang with log tables)
Bug 17876 (Truncating mysql.slow_log in a SP after using cursor locks the
thread)
Bug 23044 (Warnings on flush of a log table)
Bug 29129 (Resetting general_log while the GLOBAL READ LOCK is set causes
a deadlock)
Prior to this fix, the server would hang when performing concurrent
ALTER TABLE or TRUNCATE TABLE statements against the LOG TABLES,
which are mysql.general_log and mysql.slow_log.
The root cause traces to the following code:
in sql_base.cc, open_table()
if (table->in_use != thd)
{
/* wait_for_condition will unlock LOCK_open for us */
wait_for_condition(thd, &LOCK_open, &COND_refresh);
}
The problem with this code is that the current implementation of the
LOGGER creates 'fake' THD objects, like
- Log_to_csv_event_handler::general_log_thd
- Log_to_csv_event_handler::slow_log_thd
which are not associated to a real thread running in the server,
so that waiting for these non-existing threads to release table locks
cause the dead lock.
In general, the design of Log_to_csv_event_handler does not fit into the
general architecture of the server, so that the concept of general_log_thd
and slow_log_thd has to be abandoned:
- this implementation does not work with table locking
- it will not work with commands like SHOW PROCESSLIST
- having the log tables always opened does not integrate well with DDL
operations / FLUSH TABLES / SET GLOBAL READ_ONLY
With this patch, the fundamental design of the LOGGER has been changed to:
- always open and close a log table when writing a log
- remove totally the usage of fake THD objects
- clarify how locking of log tables is implemented in general.
See WL#3984 for details related to the new locking design.
Additional changes (misc bugs exposed and fixed):
1)
mysqldump which would ignore some tables in dump_all_tables_in_db(),
but forget to ignore the same in dump_all_views_in_db().
2)
mysqldump would also issue an empty "LOCK TABLE" command when all the tables
to lock are to be ignored (numrows == 0), instead of not issuing the query.
3)
Internal errors handlers could intercept errors but not warnings
(see sql_error.cc).
4)
Implementing a nested call to open tables, for the performance schema tables,
exposed an existing bug in remove_table_from_cache(), which would perform:
in_use->some_tables_deleted=1;
against another thread, without any consideration about thread locking.
This call inside remove_table_from_cache() was not required anyway,
since calling mysql_lock_abort() takes care of aborting -- cleanly -- threads
that might hold a lock on a table.
This line (in_use->some_tables_deleted=1) has been removed.
2007-07-27 08:31:06 +02:00
|
|
|
Handler_write 5
|
2006-06-20 12:20:32 +02:00
|
|
|
show status like '%tmp%';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Created_tmp_disk_tables 0
|
|
|
|
|
Created_tmp_files 0
|
|
|
|
|
Created_tmp_tables 0
|
|
|
|
|
show status like 'hand%write%';
|
|
|
|
|
Variable_name Value
|
WL#3984 (Revise locking of mysql.general_log and mysql.slow_log)
Bug#25422 (Hang with log tables)
Bug 17876 (Truncating mysql.slow_log in a SP after using cursor locks the
thread)
Bug 23044 (Warnings on flush of a log table)
Bug 29129 (Resetting general_log while the GLOBAL READ LOCK is set causes
a deadlock)
Prior to this fix, the server would hang when performing concurrent
ALTER TABLE or TRUNCATE TABLE statements against the LOG TABLES,
which are mysql.general_log and mysql.slow_log.
The root cause traces to the following code:
in sql_base.cc, open_table()
if (table->in_use != thd)
{
/* wait_for_condition will unlock LOCK_open for us */
wait_for_condition(thd, &LOCK_open, &COND_refresh);
}
The problem with this code is that the current implementation of the
LOGGER creates 'fake' THD objects, like
- Log_to_csv_event_handler::general_log_thd
- Log_to_csv_event_handler::slow_log_thd
which are not associated to a real thread running in the server,
so that waiting for these non-existing threads to release table locks
cause the dead lock.
In general, the design of Log_to_csv_event_handler does not fit into the
general architecture of the server, so that the concept of general_log_thd
and slow_log_thd has to be abandoned:
- this implementation does not work with table locking
- it will not work with commands like SHOW PROCESSLIST
- having the log tables always opened does not integrate well with DDL
operations / FLUSH TABLES / SET GLOBAL READ_ONLY
With this patch, the fundamental design of the LOGGER has been changed to:
- always open and close a log table when writing a log
- remove totally the usage of fake THD objects
- clarify how locking of log tables is implemented in general.
See WL#3984 for details related to the new locking design.
Additional changes (misc bugs exposed and fixed):
1)
mysqldump which would ignore some tables in dump_all_tables_in_db(),
but forget to ignore the same in dump_all_views_in_db().
2)
mysqldump would also issue an empty "LOCK TABLE" command when all the tables
to lock are to be ignored (numrows == 0), instead of not issuing the query.
3)
Internal errors handlers could intercept errors but not warnings
(see sql_error.cc).
4)
Implementing a nested call to open tables, for the performance schema tables,
exposed an existing bug in remove_table_from_cache(), which would perform:
in_use->some_tables_deleted=1;
against another thread, without any consideration about thread locking.
This call inside remove_table_from_cache() was not required anyway,
since calling mysql_lock_abort() takes care of aborting -- cleanly -- threads
that might hold a lock on a table.
This line (in_use->some_tables_deleted=1) has been removed.
2007-07-27 08:31:06 +02:00
|
|
|
Handler_write 7
|
2006-06-20 12:20:32 +02:00
|
|
|
show status like '%tmp%';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Created_tmp_disk_tables 0
|
|
|
|
|
Created_tmp_files 0
|
|
|
|
|
Created_tmp_tables 0
|
|
|
|
|
show status like 'com_show_status';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Com_show_status 8
|
|
|
|
|
rnd_diff tmp_table_diff
|
|
|
|
|
20 8
|
2007-12-15 00:27:40 +01:00
|
|
|
show global status like 'Com%function%';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Com_alter_function 0
|
|
|
|
|
Com_create_function 0
|
|
|
|
|
Com_drop_function 0
|
2007-12-19 01:27:15 +01:00
|
|
|
Com_show_function_code 0
|
|
|
|
|
Com_show_function_status 0
|
2007-12-15 00:27:40 +01:00
|
|
|
create function f1 (x INTEGER) returns integer
|
|
|
|
|
begin
|
|
|
|
|
declare ret integer;
|
|
|
|
|
set ret = x * 10;
|
|
|
|
|
return ret;
|
|
|
|
|
end //
|
|
|
|
|
drop function f1;
|
|
|
|
|
show global status like 'Com%function%';
|
|
|
|
|
Variable_name Value
|
|
|
|
|
Com_alter_function 0
|
2007-12-19 01:27:15 +01:00
|
|
|
Com_create_function 1
|
2007-12-15 00:27:40 +01:00
|
|
|
Com_drop_function 1
|
2007-12-19 01:27:15 +01:00
|
|
|
Com_show_function_code 0
|
|
|
|
|
Com_show_function_status 0
|