I have created the following procedure:
CREATE DATABASE memory
USE memory
DELIMITER $$
DROP PROCEDURE IF EXISTS `my_memory` $$
CREATE PROCEDURE `my_memory` ()
BEGIN
DECLARE var LONGTEXT;
DECLARE val LONGTEXT;
DECLARE done INT;
#Variables for storing calculations
DECLARE GLOBAL_SUM DOUBLE;
DECLARE PER_THREAD_SUM DOUBLE;
DECLARE MAX_CONN DOUBLE;
DECLARE HEAP_TABLE DOUBLE;
DECLARE TEMP_TABLE DOUBLE;
#Cursor for Global Variables
#### For MySQL 5.1+
DECLARE CUR_GBLVAR CURSOR FOR SELECT * FROM information_schema.GLOBAL_VARIABLES;
#### Ref: http://bugs.mysql.com/bug.php?id=49758
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done=1;
SET GLOBAL_SUM=0;
SET PER_THREAD_SUM=0;
SET MAX_CONN=0;
SET HEAP_TABLE=0;
SET TEMP_TABLE=0;
OPEN CUR_GBLVAR;
mylp:LOOP
FETCH CUR_GBLVAR INTO var,val;
IF done=1 THEN
LEAVE mylp;
END IF;
IF var in ('key_buffer_size','innodb_buffer_pool_size','innodb_additional_mem_pool_size','innodb_log_buffer_size','query_cache_size') THEN
#Summing Up Global Memory Usage
SET GLOBAL_SUM=GLOBAL_SUM+val;
ELSEIF var in ('read_buffer_size','read_rnd_buffer_size','sort_buffer_size','join_buffer_size','thread_stack','max_allowed_packet','net_buffer_length') THEN
#Summing Up Per Thread Memory Variables
SET PER_THREAD_SUM=PER_THREAD_SUM+val;
ELSEIF var in ('max_connections') THEN
#Maximum allowed connections
SET MAX_CONN=val;
ELSEIF var in ('max_heap_table_size') THEN
#Size of Max Heap tables created
SET HEAP_TABLE=val;
#Size of possible Temporary Table = Maximum of tmp_table_size / max_heap_table_size.
ELSEIF var in ('tmp_table_size','max_heap_table_size') THEN
SET TEMP_TABLE=if((TEMP_TABLE>val),TEMP_TABLE,val);
END IF;
END LOOP;
CLOSE CUR_GBLVAR;
#Summerizing:
select "Global Buffers" as "Parameter",CONCAT(GLOBAL_SUM/(1024*1024),' M') as "Value" union
select "Per Thread",CONCAT(PER_THREAD_SUM/(1024*1024),' M') union
select "Maximum Connections",MAX_CONN union
select "Total Memory Usage",CONCAT((GLOBAL_SUM + (MAX_CONN * PER_THREAD_SUM))/(1024*1024),' M') union
select "+ Per Heap Table",CONCAT(HEAP_TABLE / (1024*1024),' M') union
select "+ Per Temp Table",CONCAT(TEMP_TABLE / (1024*1024),' M');
END $$
DELIMITER ;
When I run the procedure, I get the following:
mysql> call my_memory();
+---------------------+------------+
| Parameter | Value |
+---------------------+------------+
| Global Buffers | 1131 M |
| Per Thread | 5.078125 M |
| Maximum Connections | 200 |
| Total Memory Usage | 2146.625 M |
| + Per Heap Table | 16 M |
| + Per Temp Table | 134 M |
+---------------------+------------+
6 rows in set (0.02 sec)
Query OK, 0 rows affected (0.06 sec)
From that information, we know the following: Total Memory Usage = Global buffer + (Memory Per Thread x Maximum Connections). = 1131 + (5.078125 x 200) = 1131 + 1015.625 = 2,146.625
When I list all the threads, there are around 50 of them:
mysql> SHOW FULL PROCESSLIST;
+--------+------+-----------------+------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+--------+------+-----------------+------+---------+------+-------+-----------------------+
| 226874 | root | localhost:58812 | NULL | Query | 0 | init | SHOW FULL PROCESSLIST |
| 226903 | wms | localhost:59532 | wms | Sleep | 0 | | NULL |
| 226904 | wms | localhost:59533 | wms | Sleep | 0 | | NULL |
| 226908 | wms | localhost:59574 | wms | Sleep | 592 | | NULL |
| 226911 | wms | localhost:59603 | wms | Sleep | 1 | | NULL |
| 226926 | wms | localhost:59976 | wms | Sleep | 0 | | NULL |
| 226927 | wms | localhost:60070 | wms | Sleep | 1 | | NULL |
| 226945 | wms | localhost:60395 | wms | Sleep | 6 | | NULL |
| 226970 | wms | localhost:61265 | wms | Sleep | 1 | | NULL |
| 226975 | wms | localhost:61378 | wms | Sleep | 147 | | NULL |
| 226984 | wms | localhost:61990 | wms | Sleep | 628 | | NULL |
| 226985 | wms | localhost:61991 | wms | Sleep | 628 | | NULL |
| 226986 | wms | localhost:61992 | wms | Sleep | 628 | | NULL |
| 226987 | wms | localhost:62087 | wms | Sleep | 600 | | NULL |
| 226988 | wms | localhost:62088 | wms | Sleep | 600 | | NULL |
| 226989 | wms | localhost:62145 | wms | Sleep | 568 | | NULL |
| 226990 | wms | localhost:62227 | wms | Sleep | 540 | | NULL |
| 226991 | wms | localhost:62333 | wms | Sleep | 508 | | NULL |
| 226992 | wms | localhost:62334 | wms | Sleep | 508 | | NULL |
| 226993 | wms | localhost:62335 | wms | Sleep | 508 | | NULL |
| 226994 | wms | localhost:62366 | wms | Sleep | 478 | | NULL |
| 226995 | wms | localhost:62367 | wms | Sleep | 478 | | NULL |
| 226996 | wms | localhost:62371 | wms | Sleep | 450 | | NULL |
| 226997 | wms | localhost:62372 | wms | Sleep | 448 | | NULL |
| 226998 | wms | localhost:62431 | wms | Sleep | 388 | | NULL |
| 226999 | wms | localhost:62432 | wms | Sleep | 388 | | NULL |
| 227000 | wms | localhost:62507 | wms | Sleep | 360 | | NULL |
| 227001 | wms | localhost:62508 | wms | Sleep | 360 | | NULL |
| 227002 | wms | localhost:62731 | wms | Sleep | 270 | | NULL |
| 227003 | wms | localhost:62732 | wms | Sleep | 270 | | NULL |
| 227004 | wms | localhost:62733 | wms | Sleep | 270 | | NULL |
| 227005 | wms | localhost:62734 | wms | Sleep | 270 | | NULL |
| 227006 | wms | localhost:62735 | wms | Sleep | 270 | | NULL |
| 227007 | wms | localhost:62736 | wms | Sleep | 270 | | NULL |
| 227008 | wms | localhost:62737 | wms | Sleep | 270 | | NULL |
| 227009 | wms | localhost:62741 | wms | Sleep | 270 | | NULL |
| 227010 | wms | localhost:62742 | wms | Sleep | 270 | | NULL |
| 227011 | wms | localhost:62743 | wms | Sleep | 270 | | NULL |
| 227012 | wms | localhost:62869 | wms | Sleep | 210 | | NULL |
| 227013 | wms | localhost:62870 | wms | Sleep | 208 | | NULL |
| 227014 | wms | localhost:62901 | wms | Sleep | 180 | | NULL |
| 227015 | wms | localhost:62902 | wms | Sleep | 180 | | NULL |
| 227016 | wms | localhost:62904 | wms | Sleep | 150 | | NULL |
| 227017 | wms | localhost:62945 | wms | Sleep | 90 | | NULL |
| 227018 | wms | localhost:62946 | wms | Sleep | 88 | | NULL |
| 227019 | wms | localhost:62974 | wms | Sleep | 58 | | NULL |
| 227020 | wms | localhost:62975 | wms | Sleep | 58 | | NULL |
| 227021 | wms | localhost:63020 | wms | Sleep | 30 | | NULL |
| 227022 | wms | localhost:63021 | wms | Sleep | 30 | | NULL |
| 227023 | wms | localhost:63022 | wms | Sleep | 30 | | NULL |
| 227024 | wms | localhost:63027 | wms | Sleep | 28 | | NULL |
+--------+------+-----------------+------+---------+------+-------+-----------------------+
Why does the my_memory()
procedure add 1015.625 MB (200 x 5.078125) as one of the values in total memory used? Shouldn't it be 50 x 5.078125 MB, since there is only 50 threads active?
In Task Manager, it shows MySQL using 1011 MB of memory. Why is this different from the MySQL procedure showing total usage as 2146 MB?
With process explorer, it show the private bytes as 1,696.440 KB and working set as 741,956K. The working sets should be the physical memory used by the process included memory-mapped files.
Why is this lower than what task manager displays?