14.18.3 InnoDB Standard Monitor and Lock Monitor Output

The Lock Monitor is the same as the Standard Monitor except that it includes additional lock information. Enabling either monitor for periodic output turns on the same output stream, but the stream includes extra information if the Lock Monitor is enabled. For example, if you enable the Standard Monitor and Lock Monitor, that turns on a single output stream. The stream includes extra lock information until you disable the Lock Monitor.

Standard Monitor output is limited to 1MB when produced using the SHOW ENGINE INNODB STATUS statement. This limit does not apply to output written to tserver standard error output (stderr).

Example Standard Monitor output:

mysql> SHOW ENGINE INNODB STATUS\G
*************************** 1. row ***************************
  Type: InnoDB
  Name:
Status:
=====================================
2014-10-16 18:37:29 0x7fc2a95c1700 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 20 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 38 srv_active, 0 srv_shutdown, 252 srv_idle
srv_master_thread log flush and writes: 290
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 119
OS WAIT ARRAY INFO: signal count 103
Mutex spin waits 0, rounds 0, OS waits 0
RW-shared spins 38, rounds 76, OS waits 38
RW-excl spins 2, rounds 9383715, OS waits 3
RW-sx spins 0, rounds 0, OS waits 0
Spin rounds per wait: 0.00 mutex, 2.00 RW-shared, 4691857.50 RW-excl,
0.00 RW-sx
------------------------
LATEST FOREIGN KEY ERROR
------------------------
2014-10-16 18:35:18 0x7fc2a95c1700 Transaction:
TRANSACTION 1814, ACTIVE 0 sec inserting
mysql tables in use 1, locked 1
4 lock struct(s), heap size 1136, 3 row lock(s), undo log entries 3
MySQL thread id 2, OS thread handle 140474041767680, query id 74 localhost
root update
INSERT INTO child VALUES
    (NULL, 1)
    , (NULL, 2)
    , (NULL, 3)
    , (NULL, 4)
    , (NULL, 5)
    , (NULL, 6)
Foreign key constraint fails for table `mysql`.`child`:
,
  CONSTRAINT `child_ibfk_1` FOREIGN KEY (`parent_id`) REFERENCES `parent`
  (`id`) ON DELETE CASCADE ON UPDATE CASCADE
Trying to add in child table, in index par_ind tuple:
DATA TUPLE: 2 fields;
 0: len 4; hex 80000003; asc     ;;
 1: len 4; hex 80000003; asc     ;;

But in parent table `mysql`.`parent`, in index PRIMARY,
the closest match we can find is record:
PHYSICAL RECORD: n_fields 3; compact format; info bits 0
 0: len 4; hex 80000004; asc     ;;
 1: len 6; hex 00000000070a; asc       ;;
 2: len 7; hex aa0000011d0134; asc       4;;

------------------------
LATEST DETECTED DEADLOCK
------------------------
2014-10-16 18:36:30 0x7fc2a95c1700
*** (1) TRANSACTION:
TRANSACTION 1824, ACTIVE 9 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 3, OS thread handle 140474041501440, query id 80 localhost
root updating
DELETE FROM t WHERE i = 1
*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 35 page no 3 n bits 72 index GEN_CLUST_INDEX of table
`mysql`.`t` trx id 1824 lock_mode X waiting
Record lock, heap no 2 PHYSICAL RECORD: n_fields 4; compact format; info
bits 0
 0: len 6; hex 000000000200; asc       ;;
 1: len 6; hex 00000000071f; asc       ;;
 2: len 7; hex b80000012b0110; asc     +  ;;
 3: len 4; hex 80000001; asc     ;;

*** (2) TRANSACTION:
TRANSACTION 1825, ACTIVE 29 sec starting index read
mysql tables in use 1, locked 1
4 lock struct(s), heap size 1136, 3 row lock(s)
MySQL thread id 2, OS thread handle 140474041767680, query id 81 localhost
root updating
DELETE FROM t WHERE i = 1
*** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 35 page no 3 n bits 72 index GEN_CLUST_INDEX of table
`mysql`.`t` trx id 1825 lock mode S
Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info
bits 0
 0: len 8; hex 73757072656d756d; asc supremum;;

Record lock, heap no 2 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
 0: len 6; hex 000000000200; asc       ;;
 1: len 6; hex 00000000071f; asc       ;;
 2: len 7; hex b80000012b0110; asc     +  ;;
 3: len 4; hex 80000001; asc     ;;

*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 35 page no 3 n bits 72 index GEN_CLUST_INDEX of table
`mysql`.`t` trx id 1825 lock_mode X waiting
Record lock, heap no 2 PHYSICAL RECORD: n_fields 4; compact format; info
bits 0
 0: len 6; hex 000000000200; asc       ;;
 1: len 6; hex 00000000071f; asc       ;;
 2: len 7; hex b80000012b0110; asc     +  ;;
 3: len 4; hex 80000001; asc     ;;

*** WE ROLL BACK TRANSACTION (1)
------------
TRANSACTIONS
------------
Trx id counter 1950
Purge done for trx's n:o < 1933 undo n:o < 0 state: running but idle
History list length 23
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 421949033065200, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 421949033064280, not started
0 lock struct(s), heap size 1136, 0 row lock(s)
---TRANSACTION 1949, ACTIVE 0 sec inserting
mysql tables in use 1, locked 1
8 lock struct(s), heap size 1136, 1850 row lock(s), undo log entries 17415
MySQL thread id 4, OS thread handle 140474041235200, query id 176 localhost
root update
INSERT INTO `salaries` VALUES (55723,39746,'1997-02-25','1998-02-25'),
(55723,40758,'1998-02-25','1999-02-25'),(55723,44559,'1999-02-25','2000-02-25'),
(55723,44081,'2000-02-25','2001-02-24'),(55723,44112,'2001-02-24','2001-08-16'),
(55724,46461,'1996-12-06','1997-12-06'),(55724,48916,'1997-12-06','1998-12-06'),
(55724,51269,'1998-12-06','1999-12-06'),(55724,51932,'1999-12-06','2000-12-05'),
(55724,52617,'2000-12-05','2001-12-05'),(55724,56658,'2001-12-05','9999-01-01'),
(55725,40000,'1993-01-30','1994-01-30'),(55725,41472,'1994-01-30','1995-01-30'),
(55725,45293,'1995-01-30','1996-01-30'),(55725,473
--------
FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests (insert buffer thread)
I/O thread 1 state: waiting for completed aio requests (log thread)
I/O thread 2 state: waiting for completed aio requests (read thread)
I/O thread 3 state: waiting for completed aio requests (read thread)
I/O thread 4 state: waiting for completed aio requests (read thread)
I/O thread 5 state: waiting for completed aio requests (read thread)
I/O thread 6 state: waiting for completed aio requests (write thread)
I/O thread 7 state: waiting for completed aio requests (write thread)
I/O thread 8 state: waiting for completed aio requests (write thread)
I/O thread 9 state: waiting for completed aio requests (write thread)
Pending normal aio reads: 0 [0, 0, 0, 0] , aio writes: 0 [0, 0, 0, 0] ,
 ibuf aio reads: 0, log i/o's: 0, sync i/o's: 0
Pending flushes (fsync) log: 0; buffer pool: 0
224 OS file reads, 5770 OS file writes, 803 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 264.84 writes/s, 23.05 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 4425293, node heap has 444 buffer(s)
68015.25 hash searches/s, 106259.24 non-hash searches/s
---
LOG
---
Log sequence number 165913808
Log flushed up to   164814979
Pages flushed up to 141544038
Last checkpoint at  130503656
0 pending log flushes, 0 pending chkp writes
258 log i/o's done, 6.65 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total large memory allocated 2198863872
Dictionary memory allocated 776332
Buffer pool size   131072
Free buffers       124908
Database pages     5720
Old database pages 2071
Modified db pages  910
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 4, not young 0
0.10 youngs/s, 0.00 non-youngs/s
Pages read 197, created 5523, written 5060
0.00 reads/s, 190.89 creates/s, 244.94 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: 5720, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
----------------------
INDIVIDUAL BUFFER POOL INFO
----------------------
---BUFFER POOL 0
Buffer pool size   65536
Free buffers       62412
Database pages     2899
Old database pages 1050
Modified db pages  449
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 3, not young 0
0.05 youngs/s, 0.00 non-youngs/s
Pages read 107, created 2792, written 2586
0.00 reads/s, 92.65 creates/s, 122.89 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: 2899, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 1
Buffer pool size   65536
Free buffers       62496
Database pages     2821
Old database pages 1021
Modified db pages  461
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 1, not young 0
0.05 youngs/s, 0.00 non-youngs/s
Pages read 90, created 2731, written 2474
0.00 reads/s, 98.25 creates/s, 122.04 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: 2821, 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=35909, Main thread ID=140471692396288, state: sleeping
Number of rows inserted 1526363, updated 0, deleted 3, read 11
52671.72 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================

Standard Monitor Output Sections

For a description of each metric reported by the Standard Monitor, refer to the Metrics chapter in the Oracle Enterprise Manager for MySQL Database User's Guide.

• Status

  This section shows the timestamp, the monitor name, and the number of seconds that per-second averages are based on. The number of seconds is the elapsed time between the current time and the last time InnoDB Monitor output was printed.

• BACKGROUND THREAD

  The srv_master_thread lines shows work done by the main background thread.

• SEMAPHORES

  This section reports threads waiting for a semaphore and statistics on how many times threads have needed a spin or a wait on a mutex or a rw-lock semaphore. A large number of threads waiting for semaphores may be a result of disk I/O, or contention problems inside InnoDB. Contention can be due to heavy parallelism of queries or problems in operating system thread scheduling. Setting the innodb_thread_concurrency system variable smaller than the default value might help in such situations. The Spin rounds per wait line shows the number of spinlock rounds per OS wait for a mutex.

  Mutex metrics are reported by SHOW ENGINE INNODB MUTEX.

• LATEST FOREIGN KEY ERROR

  This section provides information about the most recent foreign key constraint error. It is not present if no such error has occurred. The contents include the statement that failed as well as information about the constraint that failed and the referenced and referencing tables.

• LATEST DETECTED DEADLOCK

  This section provides information about the most recent deadlock. It is not present if no deadlock has occurred. The contents show which transactions are involved, the statement each was attempting to execute, the locks they have and need, and which transaction InnoDB decided to roll back to break the deadlock. The lock modes reported in this section are explained in Section 14.7.1, “InnoDB Locking”.

• TRANSACTIONS

  If this section reports lock waits, your applications might have lock contention. The output can also help to trace the reasons for transaction deadlocks.

• FILE I/O

  This section provides information about threads that InnoDB uses to perform various types of I/O. The first few of these are dedicated to general InnoDB processing. The contents also display information for pending I/O operations and statistics for I/O performance.

  The number of these threads are controlled by the innodb_read_io_threads and innodb_write_io_threads parameters. See Section 14.15, “InnoDB Startup Options and System Variables”.

• INSERT BUFFER AND ADAPTIVE HASH INDEX

  This section shows the status of the InnoDB insert buffer (also referred to as the change buffer) and the adaptive hash index.

  For related information, see Section 14.5.2, “Change Buffer”, and Section 14.5.3, “Adaptive Hash Index”.

• LOG

  This section displays information about the InnoDB log. The contents include the current log sequence number, how far the log has been flushed to disk, and the position at which InnoDB last took a checkpoint. (See Section 14.12.3, “InnoDB Checkpoints”.) The section also displays information about pending writes and write performance statistics.

• BUFFER POOL AND MEMORY

  This section gives you statistics on pages read and written. You can calculate from these numbers how many data file I/O operations your queries currently are doing.

  For buffer pool statistics descriptions, see Monitoring the Buffer Pool Using the InnoDB Standard Monitor. For additional information about the operation of the buffer pool, see Section 14.5.1, “Buffer Pool”.

• ROW OPERATIONS

  This section shows what the main thread is doing, including the number and performance rate for each type of row operation.