I have an Amazon 24XL server
- 96 Cores
- 378 GB RAM
- Database size 5.7G
- Debian GNU/Linux 9 (stretch)
- PHP 7.3.16
- mysql Ver 15.1 Distrib 10.3.22-MariaDB
I have only one WordPress site where users read articles, there are 4-5 small plugins One plugins is used to add the points and rewards in my subscribers profile. When there are around 2500 Users on my site there are around 3000+ UPDATE queries that runs to update the table 'wp_custom_points_user'
The issue is that the queries stuck in updating I can't find the way to fix those things However server has much RAM , CPU available but due to queries on the same table it stuck and caused 502 on my site. I am looking to optimize MySQL to cater concurrent update queries as they are taking longer to respond and I suspect there are some locks. However I have all tables with indexing and using InnoDB
Here is the SHOW ENGINE INNODB STATUS;
=====================================
2020-04-06 13:45:46 0x7f934bf24700 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 27 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 8196 srv_active, 0 srv_shutdown, 0 srv_idle
srv_master_thread log flush and writes: 8196
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 15589494
OS WAIT ARRAY INFO: signal count 41500023
RW-shared spins 0, rounds 154525943, OS waits 1459106
RW-excl spins 0, rounds 10328037, OS waits 40587
RW-sx spins 71982, rounds 547220, OS waits 3916
Spin rounds per wait: 154525943.00 RW-shared, 10328037.00 RW-excl, 7.60 RW-sx
------------
TRANSACTIONS
------------
Trx id counter 351880322
Purge done for trx's n:o < 351880319 undo n:o < 0 state: running
History list length 1
... truncated...
mpact format; info bits 0
0: len 4; hex 80000001; asc ;;
1: len 6; hex 000000000000; asc ;;
2: len 7; hex 80000000000000; asc ;;
3: len 4; hex 80004cd6; asc L ;;
4: len 4; hex 800186b0; asc ;;
------------------
---TRANSACTION 351861705, ACTIVE 40 sec starting index read
mysql tables in use 1, locked 1
LOCK WAIT 2 lock struct(s), heap size 1136, 1 row lock(s)
MySQL thread id 421774, OS thread handle 140270896170752, query id 8187691 localhost wpdatabayf Updating
UPDATE `wp_custom_points_user` SET `total_points` = '18900' WHERE `user_id` = 188768
------- TRX HAS BEEN WAITING 40 SEC FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 1468 page no 5 n bits 568 index PRIMARY of table `wpdatabayf`.`wp_custom_points_user` trx id 351861705 lock_mode X waiting
Record lock, heap no 2 PHYSICAL RECORD: n_fields 5; compact format; info bits 0
0: len 4; hex 80000001; asc ;;
1: len 6; hex 000000000000; asc ;;
2: len 7; hex 80000000000000; asc ;;
3: len 4; hex 80004cd6; asc L ;;
4: len 4; hex 800186b0; asc ;;
---BUFFER POOL 1
.
.
.
.
---BUFFER POOL 31
Buffer pool size 8192
Free buffers 1725
Database pages 6096
Old database pages 2253
Modified db pages 183
Percent of dirty pages(LRU & free pages): 2.340
Max dirty pages percent: 75.000
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 0, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 5594, created 502, written 12349
0.00 reads/s, 0.00 creates/s, 0.74 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 6096, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
--------------
ROW OPERATIONS
--------------
0 queries inside InnoDB, 0 queries in queue
2 read views open inside InnoDB
Process ID=72108, Main thread ID=140323093444352, state: sleeping
Number of rows inserted 88380, updated 193228, deleted 34011, read 84305568368
11.44 inserts/s, 21.74 updates/s, 0.00 deletes/s, 12469107.55 reads/s
Number of system rows inserted 0, updated 0, deleted 0, read 0
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================
UPDATE
SHOW CREATE TABLE wp_custom_points_user;
+----------------------------------+------------------------------------------------------+
| Table | Create Table |
+----------------------------------+------------------------------------------------------+
| wp_custom_points_user | CREATE TABLE `wp_custom_points_user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`total_points` int(11) NOT NULL,
`user_id` int(11) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `ixd_uc_tzs_wp_custom_points_user` (`user_id`)
) ENGINE=InnoDB AUTO_INCREMENT=199180 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci |
+----------------------------------+------------------------------------------------------+
SHOW INDEX FROM wp_custom_points_user;
+----------------------------------+------------+---------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+----------------------------------+------------+---------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| wp_custom_points_user | 0 | PRIMARY | 1 | id | A | 171334 | NULL | NULL | | BTREE | | |
| wp_custom_points_user | 0 | ixd_uc_tzs_wp_custom_points_user | 1 | user_id | A | 171334 | NULL | NULL | | BTREE | | |
+----------------------------------+------------+---------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
