找出mysql 中谁持有表锁

mysql> show processlist;
+----+------+-----------+------+---------+------+-------+------------------+
| Id | User | Host      | db   | Command | Time | State | Info             |
+----+------+-----------+------+---------+------+-------+------------------+
|  1 | test |           | NULL | Sleep   |    4 |       | NULL             |
|  2 | root | localhost | NULL | Query   |    0 | init  | show processlist |
|  3 | test | localhost | test | Sleep   |    6 |       | NULL             |
+----+------+-----------+------+---------+------+-------+------------------+
3 rows in set (0.00 sec)

模拟持有的read 锁ID为3,

ID=3:
mysql> lock table t1 read;
Query OK, 0 rows affected (0.00 sec)



mysql>  show processlist;
+----+------+-----------+------+---------+------+-------+------------------+
| Id | User | Host      | db   | Command | Time | State | Info             |
+----+------+-----------+------+---------+------+-------+------------------+
|  1 | test |           | NULL | Sleep   |    2 |       | NULL             |
|  2 | root | localhost | NULL | Query   |    0 | init  | show processlist |
|  3 | test | localhost | test | Sleep   |   26 |       | NULL             |
|  4 | test | localhost | NULL | Sleep   |    6 |       | NULL             |
+----+------+-----------+------+---------+------+-------+------------------+
4 rows in set (0.00 sec)


启用Id4的回话:
mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> insert into t1 values(3);



mysql> show engine innodb statusG
*************************** 1. row ***************************
  Type: InnoDB  --数据库引擎类型 InnoDB
  Name: 
Status: 
=====================================
2015-03-12 07:27:33 7f53861e7700 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 8 seconds  ---最近8秒每秒平均计算
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 2 srv_active, 0 srv_shutdown, 432 srv_idle
srv_master_thread log flush and writes: 434
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 3
OS WAIT ARRAY INFO: signal count 3
Mutex spin waits 1, rounds 30, OS waits 1
RW-shared spins 2, rounds 60, OS waits 2
RW-excl spins 0, rounds 0, OS waits 0
Spin rounds per wait: 30.00 mutex, 30.00 RW-shared, 0.00 RW-excl
------------
TRANSACTIONS               -----事务信息
------------
Trx id counter 15624
Purge done for trx's n:o < 15126 undo n:o < 0 state: running but idle
History list length 26


LIST OF TRANSACTIONS FOR EACH SESSION:   --列出了每个SESSION的事务

---TRANSACTION 0, not started
MySQL thread id 2, OS thread handle 0x7f53861e7700, query id 112 localhost root init
show engine innodb status

---TRANSACTION 0, not started
mysql tables in use 1, locked 1
MySQL thread id 4, OS thread handle 0x7f5386165700, query id 75 localhost test Waiting for table level lock
insert into t1 values(3)

---说明thread id =4 执行的sql是insert into t1 values(3) 正在等外锁


---TRANSACTION 15623, ACTIVE 319 sec
mysql tables in use 1, locked 1
1 lock struct(s), heap size 360, 0 row lock(s)  ---thread id=3 持有一个锁结构
MySQL thread id 3, OS thread handle 0x7f53861a6700, query id 38 localhost test cleaning up
--------
FILE I/O
--------
I/O thread 0 state: waiting for i/o request (insert buffer thread)
I/O thread 1 state: waiting for i/o request (log thread)
I/O thread 2 state: waiting for i/o request (read thread)
I/O thread 3 state: waiting for i/o request (read thread)
I/O thread 4 state: waiting for i/o request (read thread)
I/O thread 5 state: waiting for i/o request (read thread)
I/O thread 6 state: waiting for i/o request (write thread)
I/O thread 7 state: waiting for i/o request (write thread)
I/O thread 8 state: waiting for i/o request (write thread)
I/O thread 9 state: waiting for i/o request (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
214 OS file reads, 5 OS file writes, 5 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 276671, node heap has 0 buffer(s)
0.00 hash searches/s, 0.00 non-hash searches/s
---
LOG
---
Log sequence number 1685701
Log flushed up to   1685701
Pages flushed up to 1685701
Last checkpoint at  1685701
0 pending log writes, 0 pending chkp writes
8 log i/o's done, 0.00 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total memory allocated 137363456; in additional pool allocated 0
Dictionary memory allocated 68091
Buffer pool size   8191
Free buffers       7994
Database pages     197
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 197, created 0, written 1
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 197, 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
Main thread process no. 26975, id 139996673111808, state: sleeping
Number of 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
============================

1 row in set (0.00 sec)