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1、查询进程
show processlist
2、 查询到相对应的进程，然后 kill id
验证（kill后再看是否还有锁）
2、查询是否锁表
? 1show open tables where in_use > 0;
示例：
新建一个会话执行如下的显示锁示例
? 1 2 3lock tables account_data.account read;
select sleep(160);
unlock tables account_data.account;
另开启一个会话检查锁表情况：
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66mysql> show open tables where in_use > 0;
+--------------+---------+--------+-------------+
| database | table | in_use | name_locked |
+--------------+---------+--------+-------------+
| account_data | account | 1 | 0 |
+--------------+---------+--------+-------------+
1 row in set (0.00 sec)
mysql> select * from information_schema.innodb_locksg;
empty set, 1 warning (0.00 sec)
error:
no query specified
mysql> show processlistg;
*************************** 1. row ***************************
id: 5
user: root
host: 192.168.0.206:64294
db: null
command: sleep
time: 4051
state:
info: null
*************************** 2. row ***************************
id: 8
user: root
host: 192.168.0.206:64297
db: null
command: sleep
time: 4042
state:
info: null
*************************** 3. row ***************************
id: 10
user: root
host: localhost
db: null
command: query
time: 0
state: starting
info: show processlist
*************************** 4. row ***************************
id: 19
user: root
host: 192.168.0.206:54603
db: account_data
command: sleep
time: 245
state:
info: null
*************************** 5. row ***************************
id: 20
user: root
host: 192.168.0.206:54604
db: information_schema
command: query
time: 20
state: user sleep
info: select sleep(160)
5 rows in set (0.00 sec)
error:
no query specified
mysql>
3、在5.5中，information_schema 库中增加了三个关于锁的表（innodb引擎）：
innodb_trx ## 当前运行的所有事务
innodb_locks ## 当前出现的锁
innodb_lock_waits ## 锁等待的对应关系
先来看一下这三张表结构：
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56root@127.0.0.1 : information_schema 13:28:38> desc innodb_locks;
+————-+———————+——+—–+———+——-+
| field | type | null | key | default | extra |
+————-+———————+——+—–+———+——-+
| lock_id | varchar(81) | no | | | |#锁id
| lock_trx_id | varchar(18) | no | | | |#拥有锁的事务id
| lock_mode | varchar(32) | no | | | |#锁模式
| lock_type | varchar(32) | no | | | |#锁类型
| lock_table | varchar(1024) | no | | | |#被锁的表
| lock_index | varchar(1024) | yes | | null | |#被锁的索引
| lock_space | bigint(21) unsigned | yes | | null | |#被锁的表空间号
| lock_page | bigint(21) unsigned | yes | | null | |#被锁的页号
| lock_rec | bigint(21) unsigned | yes | | null | |#被锁的记录号
| lock_data | varchar(8192) | yes | | null | |#被锁的数据
+————-+———————+——+—–+———+——-+
10 rows in set (0.00 sec)
root@127.0.0.1 : information_schema 13:28:56> desc innodb_lock_waits;
+——————-+————-+——+—–+———+——-+
| field | type | null | key | default | extra |
+——————-+————-+——+—–+———+——-+
| requesting_trx_id | varchar(18) | no | | | |#请求锁的事务id
| requested_lock_id | varchar(81) | no | | | |#请求锁的锁id
| blocking_trx_id | varchar(18) | no | | | |#当前拥有锁的事务id
| blocking_lock_id | varchar(81) | no | | | |#当前拥有锁的锁id
+——————-+————-+——+—–+———+——-+
4 rows in set (0.00 sec)
root@127.0.0.1 : information_schema 13:29:05> desc innodb_trx ;
+—————————-+———————+——+—–+———————+——-+
| field | type | null | key | default | extra |
+—————————-+———————+——+—–+———————+——-+
| trx_id | varchar(18) | no | | | |#事务id
| trx_state | varchar(13) | no | | | |#事务状态：
| trx_started | datetime | no | | 0000-00-00 00:00:00 | |#事务开始时间；
| trx_requested_lock_id | varchar(81) | yes | | null | |#innodb_locks.lock_id
| trx_wait_started | datetime | yes | | null | |#事务开始等待的时间
| trx_weight | bigint(21) unsigned | no | | 0 | |#
| trx_mysql_thread_id | bigint(21) unsigned | no | | 0 | |#事务线程id
| trx_query | varchar(1024) | yes | | null | |#具体sql语句
| trx_operation_state | varchar(64) | yes | | null | |#事务当前操作状态
| trx_tables_in_use | bigint(21) unsigned | no | | 0 | |#事务中有多少个表被使用
| trx_tables_locked | bigint(21) unsigned | no | | 0 | |#事务拥有多少个锁
| trx_lock_structs | bigint(21) unsigned | no | | 0 | |#
| trx_lock_memory_bytes | bigint(21) unsigned | no | | 0 | |#事务锁住的内存大小（b）
| trx_rows_locked | bigint(21) unsigned | no | | 0 | |#事务锁住的行数
| trx_rows_modified | bigint(21) unsigned | no | | 0 | |#事务更改的行数
| trx_concurrency_tickets | bigint(21) unsigned | no | | 0 | |#事务并发票数
| trx_isolation_level | varchar(16) | no | | | |#事务隔离级别
| trx_unique_checks | int(1) | no | | 0 | |#是否唯一性检查
| trx_foreign_key_checks | int(1) | no | | 0 | |#是否外键检查
| trx_last_foreign_key_error | varchar(256) | yes | | null | |#最后的外键错误
| trx_adaptive_hash_latched | int(1) | no | | 0 | |#
| trx_adaptive_hash_timeout | bigint(21) unsigned | no | | 0 | |#
+—————————-+———————+——+—–+———————+——-+
22 rows in set (0.01 sec)
查看正在锁的事务
? 1select * from information_schema.innodb_locks;
查看等待锁的事务
? 1select * from information_schema.innodb_lock_waits;
查看锁阻塞线程信息
3.1 使用show processlist查看
3.2 直接使用show engine innodb status查看
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53------------
transactions
------------
trx id counter 4131
purge done for trx's n:o < 4119 undo n:o < 0 state: running but idle
history list length 126
list of transactions for each session:
---transaction 0, not started
mysql thread id 2, os thread handle 0x7f953ffff700, query id 115 localhost root init
show engine innodb status
---transaction 4130, active 41 sec starting index read
mysql tables in use 1, locked 1
lock wait 2 lock struct(s), heap size 360, 1 row lock(s)
mysql thread id 4, os thread handle 0x7f953ff9d700, query id 112 localhost root updating
delete from emp where empno=7788
------- trx has been waiting 41 sec for this lock to be granted: ## 等待了41s
record locks space id 16 page no 3 n bits 88 index `primary` of table `test`.`emp` trx id 4130 lock_mode x locks rec but not gap waiting
record lock, heap no 9 physical record: n_fields 10; compact format; info bits 0 ## 线程4在等待往test.emp中的主键上加x锁，page num=3
0: len 4; hex 80001e6c; asc l;;
1: len 6; hex 000000001018; asc ;;
2: len 7; hex 91000001420084; asc b ;;
3: len 5; hex 53434f5454; asc scott;;
4: len 7; hex 414e414c595354; asc analyst;;
5: len 4; hex 80001d8e; asc ;;
6: len 4; hex 208794f0; asc ;;
7: len 4; hex 80000bb8; asc ;;
8: sql null;
9: len 4; hex 80000014; asc ;;
------------------
---transaction 4129, active 45 sec starting index read
mysql tables in use 1, locked 1
lock wait 2 lock struct(s), heap size 360, 1 row lock(s)
mysql thread id 7, os thread handle 0x7f953ff6c700, query id 111 localhost root updating
update emp set sal=3500 where empno=7788
------- trx has been waiting 45 sec for this lock to be granted: ## 等待了45s
record locks space id 16 page no 3 n bits 88 index `primary` of table `test`.`emp` trx id 4129 lock_mode x locks rec but not gap waiting
record lock, heap no 9 physical record: n_fields 10; compact format; info bits 0 ## 线程7在等待往test.emp中的主键上加x锁，page num=3
0: len 4; hex 80001e6c; asc l;;
1: len 6; hex 000000001018; asc ;;
2: len 7; hex 91000001420084; asc b ;;
3: len 5; hex 53434f5454; asc scott;;
4: len 7; hex 414e414c595354; asc analyst;;
5: len 4; hex 80001d8e; asc ;;
6: len 4; hex 208794f0; asc ;;
7: len 4; hex 80000bb8; asc ;;
8: sql null;
9: len 4; hex 80000014; asc ;;
------------------
---transaction 4128, active 51 sec
2 lock struct(s), heap size 360, 1 row lock(s)
mysql thread id 3, os thread handle 0x7f953ffce700, query id 110 localhost root cleaning up
我们知道，主要根因还是thread=3引起的，但从innodb status中却无法分析得到这个结果。
从上面来看，线程4和线程7都在等待往test.emp中的主键上加x锁，page num=3，但是线程7等待的时间为45s，而线程4等待的时间为41s，是较线程7之后申请的锁，所以可以判断是线程7阻塞了线程4。至于线程7为什么出现等待，这里分析不到根因。
3.3 使用mysqladmin debug查看
? 1# mysqladmin -s /tmp/mysql3306.sock debug
然后在error日志中，会看到：
? 1 2 3 4 5thread database.table_name locked/waiting lock_type
3 test.t3 locked - read low priority read lock
7 test.emp locked - write high priority write lock
这种方法中，能找到线程id=3和7是阻塞者，但还是不太准确，判断不出来线程7也是被线程id=3阻塞的。
3.4 使用innodb_lock_monitor来获取阻塞锁线程
? 1 2 3 4 5 6 7 8 9mysql [test]> create table innodb_lock_monitor (a int) engine=innodb; ## 随便在一个数据库中创建这个表，就会打开lock monitor
query ok, 0 rows affected, 1 warning (0.07 sec)
mysql [test]> show warningsg
*************************** 1. row ***************************
level: warning
code: 131
message: using the table name innodb_lock_monitor to enable diagnostic output is deprecated and may be removed in future releases. use information_schema or performance_schema tables or set global innodb_status_output=on.
1 row in set (0.00 sec)
说明：这个在5.6中有一个warning，但不影响使用。
然后再使用show engine innodb status查看：
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97------------
transactions
------------
trx id counter 4667
purge done for trx's n:o < 4659 undo n:o < 0 state: running but idle
history list length 138
list of transactions for each session:
---transaction 0, not started
mysql thread id 9, os thread handle 0x7f813c5f7700, query id 152 localhost root init
show engine innodb status
---transaction 4663, active 78 sec starting index read
mysql tables in use 1, locked 1
lock wait 2 lock struct(s), heap size 360, 1 row lock(s)
mysql thread id 4, os thread handle 0x7f813c628700, query id 149 localhost root updating
delete from emp where empno=7788
------- trx has been waiting 78 sec for this lock to be granted: ## 等待了78s
record locks space id 16 page no 3 n bits 88 index `primary` of table `test`.`emp` trx id 4663 lock_mode x locks rec but not gap waiting
record lock, heap no 9 physical record: n_fields 10; compact format; info bits 0 ## 线程4在等待往test.emp中的主键上加x锁，page num=3
0: len 4; hex 80001e6c; asc l;;
1: len 6; hex 000000001018; asc ;;
2: len 7; hex 91000001420084; asc b ;;
3: len 5; hex 53434f5454; asc scott;;
4: len 7; hex 414e414c595354; asc analyst;;
5: len 4; hex 80001d8e; asc ;;
6: len 4; hex 208794f0; asc ;;
7: len 4; hex 80000bb8; asc ;;
8: sql null;
9: len 4; hex 80000014; asc ;;
------------------
table lock table `test`.`emp` trx id 4663 lock mode ix ## 在给主键行上加x锁之前，先要在表上加意向锁ix
record locks space id 16 page no 3 n bits 88 index `primary` of table `test`.`emp` trx id 4663 lock_mode x locks rec but not gap waiting
record lock, heap no 9 physical record: n_fields 10; compact format; info bits 0
0: len 4; hex 80001e6c; asc l;;
1: len 6; hex 000000001018; asc ;;
2: len 7; hex 91000001420084; asc b ;;
3: len 5; hex 53434f5454; asc scott;;
4: len 7; hex 414e414c595354; asc analyst;;
5: len 4; hex 80001d8e; asc ;;
6: len 4; hex 208794f0; asc ;;
7: len 4; hex 80000bb8; asc ;;
8: sql null;
9: len 4; hex 80000014; asc ;;
---transaction 4662, active 81 sec starting index read
mysql tables in use 1, locked 1
lock wait 2 lock struct(s), heap size 360, 1 row lock(s)
mysql thread id 7, os thread handle 0x7f813c5c6700, query id 148 localhost root updating
update emp set sal=3500 where empno=7788
------- trx has been waiting 81 sec for this lock to be granted: ## 等待了81s
record locks space id 16 page no 3 n bits 88 index `primary` of table `test`.`emp` trx id 4662 lock_mode x locks rec but not gap waiting
record lock, heap no 9 physical record: n_fields 10; compact format; info bits 0 ## 线程7在等待往test.emp中的主键上加x锁，page num=3
0: len 4; hex 80001e6c; asc l;;
1: len 6; hex 000000001018; asc ;;
2: len 7; hex 91000001420084; asc b ;;
3: len 5; hex 53434f5454; asc scott;;
4: len 7; hex 414e414c595354; asc analyst;;
5: len 4; hex 80001d8e; asc ;;
6: len 4; hex 208794f0; asc ;;
7: len 4; hex 80000bb8; asc ;;
8: sql null;
9: len 4; hex 80000014; asc ;;
------------------
table lock table `test`.`emp` trx id 4662 lock mode ix ## 在给主键行上加x锁之前，先要在表上加意向锁ix
record locks space id 16 page no 3 n bits 88 index `primary` of table `test`.`emp` trx id 4662 lock_mode x locks rec but not gap waiting
record lock, heap no 9 physical record: n_fields 10; compact format; info bits 0
0: len 4; hex 80001e6c; asc l;;
1: len 6; hex 000000001018; asc ;;
2: len 7; hex 91000001420084; asc b ;;
3: len 5; hex 53434f5454; asc scott;;
4: len 7; hex 414e414c595354; asc analyst;;
5: len 4; hex 80001d8e; asc ;;
6: len 4; hex 208794f0; asc ;;
7: len 4; hex 80000bb8; asc ;;
8: sql null;
9: len 4; hex 80000014; asc ;;
---transaction 4615, active 1579 sec, thread declared inside innodb 1222
mysql tables in use 2, locked 0
2 lock struct(s), heap size 360, 1 row lock(s)
mysql thread id 3, os thread handle 0x7f813c659700, query id 147 localhost root sending data
select count(*) from t3 a,t3 b ## 这是线程3当前正在执行的sql
trx read view will not see trx with id >= 4662, sees < 4659
table lock table `test`.`emp` trx id 4615 lock mode ix ## 线程3中正在拥有表上的意向ix锁，并且有test.emp表上主键的行级x锁，page num=3
record locks space id 16 page no 3 n bits 88 index `primary` of table `test`.`emp` trx id 4615 lock_mode x locks rec but not gap
record lock, heap no 9 physical record: n_fields 10; compact format; info bits 0
0: len 4; hex 80001e6c; asc l;;
1: len 6; hex 000000001018; asc ;;
2: len 7; hex 91000001420084; asc b ;;
3: len 5; hex 53434f5454; asc scott;;
4: len 7; hex 414e414c595354; asc analyst;;
5: len 4; hex 80001d8e; asc ;;
6: len 4; hex 208794f0; asc ;;
7: len 4; hex 80000bb8; asc ;;
8: sql null;
9: len 4; hex 80000014; asc ;;
为什么线程3当前执行的是一个select t3表操作，但却锁住了test.emp表上page num=3？
有可能是线程3之前对test.emp表的操作事务没有及时提交导致。
所以得出：线程3阻塞了线程7，而线程7又阻塞了线程4，所以根因就是线程3，让线程3尽快提交或是kill掉即可。
3.5、 查看表锁的情况：
? 1 2 3 4 5 6 7mysql> show status like 'table%';
+----------------------------+---------+
| variable_name | value |
+----------------------------+---------+
| table_locks_immediate | 100 |
| table_locks_waited | 11 |
+----------------------------+---------+
3.6、查看innodb_row_lock状态变量来分析系统上的行锁的争夺情况：
? 1 2 3 4 5 6 7 8 9 10 11 12 13mysql> show status like 'innodb_row_lock%';
+-------------------------------+--------+
| variable_name | value |
+-------------------------------+--------+
| innodb_row_lock_current_waits | 0 |
| innodb_row_lock_time | 159372 |
| innodb_row_lock_time_avg | 39843 |
| innodb_row_lock_time_max | 51154 |
| innodb_row_lock_waits | 4 |
+-------------------------------+--------+
5 rows in set (0.01 sec)
mysql>
4. 结论
在分析innodb中锁阻塞时，几种方法的对比情况：
（1）使用show processlist查看不靠谱；
（2）直接使用show engine innodb status查看，无法判断到问题的根因；
（3）使用mysqladmin debug查看，能看到所有产生锁的线程，但无法判断哪个才是根因；
（4）开启innodb_lock_monitor后，再使用show engine innodb status查看，能够找到锁阻塞的根因。
参考：http://www.zzvips.com/article/147156.html
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原文链接：https://www.cnblogs.com/duanxz/p/4394641.html
