How to debug Lock wait timeout exceeded on MySQL?

MySQLMySQLi Database

The debug Lock wait timeout situation occurs because of some threads. If one thread is holding on to some records for a very long time, it means the thread has exceeded time.

To see all the details, implement the following query −

mysql> SHOW ENGINE INNODB STATUS;

The following is the output.

+--------+------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Type   | Name | Status                                                           |
+--------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| InnoDB |      |
=====================================
2018-10-23 09:55:05 0x19e8 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 7 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 2 srv_active, 0 srv_shutdown, 17805 srv_idle
srv_master_thread log flush and writes: 0
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 3
OS WAIT ARRAY INFO: signal count 3
RW-shared spins 0, rounds 0, OS waits 0
RW-excl spins 0, rounds 0, OS waits 0
RW-sx spins 0, rounds 0, OS waits 0
Spin rounds per wait: 0.00 RW-shared, 0.00 RW-excl, 0.00 RW-sx
------------
TRANSACTIONS
------------
Trx id counter 21000
Purge done for trx's n:o < 20998 undo n:o < 0 state: running but idle
History list length 3
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 283438498772800, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
--------
FILE I/O
--------
I/O thread 0 state: wait Windows aio (insert buffer thread)
I/O thread 1 state: wait Windows aio (log thread)
I/O thread 2 state: wait Windows aio (read thread)
I/O thread 3 state: wait Windows aio (read thread)
I/O thread 4 state: wait Windows aio (read thread)
I/O thread 5 state: wait Windows aio (read thread)
I/O thread 6 state: wait Windows aio (write thread)
I/O thread 7 state: wait Windows aio (write thread)
I/O thread 8 state: wait Windows aio (write thread)
I/O thread 9 state: wait Windows aio (write thread)
Pending normal aio reads: [0, 0, 0, 0] , aio writes: [0, 0, 0, 0] ,
 ibuf aio reads:, log i/o's:, sync i/o's:
Pending flushes (fsync) log: 0; buffer pool: 0
1025 OS file reads, 545 OS file writes, 11 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s
-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 0, seg size 2, 0 merges
merged operations:
 insert 0, delete mark 0, delete 0
discarded operations:
 insert 0, delete mark 0, delete 0
Hash table size 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 1 buffer(s)
Hash table size 2267, node heap has 3 buffer(s)
Hash table size 2267, node heap has 1 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
Hash table size 2267, node heap has 0 buffer(s)
0.00 hash searches/s, 0.29 non-hash searches/s
---
LOG
---
Log sequence number          24309079
Log buffer assigned up to    24309079
Log buffer completed up to   24309079
Log written up to            24309079
Log flushed up to            24309079
Added dirty pages up to      24309079
Pages flushed up to          24309079
Last checkpoint at           24309079
388 log i/o's done, 0.00 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total large memory allocated 8585216
Dictionary memory allocated 361173
Buffer pool size   512
Free buffers       251
Database pages     256
Old database pages 0
Modified db pages  0
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 1002, created 132, written 144
0.00 reads/s, 0.00 creates/s, 0.00 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: 256, 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
0 read views open inside InnoDB
Process ID = 3260, Main thread ID = 000000000000106C , state = sleeping
Number of rows inserted 0, updated 313, deleted 0, read 4534
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.14 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================
                                                                                      |
+--------+------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>

The above shows all the details related to the thread and I/O.

raja
Published on 21-Nov-2018 11:44:02
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