new post

docker-compose.yml

@@ -4,7 +4,7 @@ services:
     image: ddsderek/easyimage:latest
     container_name: easyimage
     ports:
-      - '8080:80'
+      - '8087:80'
     environment:
       - TZ=Asia/Shanghai
       - PUID=1002
@@ -13,4 +13,4 @@ services:
     volumes:
       - './public/config:/app/web/config'
       - './public/api/i:/app/web/i'
-    restart: unless-stopped
+    restart: unless-stopped

src/content/posts/中间件/MySQL/MySQL中发生死锁如何解决.md

@@ -0,0 +1,238 @@
+---
+title: MySQL中发生死锁如何解决
+published: 2025-09-08
+description: 'MySQL中发生死锁如何解决'
+image: ''
+tags: ['MySQL','死锁']
+category: '中间件 > MySQL'
+draft: false 
+lang: ''
+---
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/10jgi3w-1.webp)
+
+
+
+# 自动检测与回滚
+MySQL自带死锁检测机制（innodb_deadlock_detect），当检测到死锁的时候，数据库会自动回滚其中一个事务，以接触死锁，通常会回滚事务中持有最少资源的那个。
+
+也有锁等待超时的参数（innodb_lock_wait_timeout），当锁等待超过这个时间后，MySQL会自动回滚。
+
+# 手动kill发生死锁的语句
+可以通过命令，手动快速找出被阻塞的事务以及线程ID，然后手动Kill掉，及时释放资源。
+
+# 常见降低/排除死锁出现情况的方法
+- 避免大事务： 大事务占据锁耗时长，可以把大事务拆分成多个小事务执行快速释放锁，可以降低死锁产生的概率和冲突
+- 调整申请锁的顺序： 在写操作的时候保证能获得足够范围的锁，如修改操作的时候先获取排他锁再获取共享锁，固定顺序访问数据
+- 更改数据隔离级别： 可重复读比读已提交多了间隙锁和临键锁，使用读已提交能降低死锁出现的情况。
+- 合理建立索引，减少加锁范围
+- 开启死锁检测，适当调整锁等待超时时间
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/11d3nuc-1.webp)
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/11d5hm7-1.webp)
+
+# 实际测试
+innodb_print_all_deadlocks：开启死锁打印
+```sql
+show VARIABLES like 'innodb_print_all_deadlocks';
+
+set GLOBAL innodb_print_all_deadlocks = 1;
+
+flush PRIVILEGES;
+
+```
+
+```sql
+
+create table deadlock_test (
+  id bigint not null,
+  name varchar(255),
+  primary key(id)
+);
+insert into deadlock_test values(1, 'zhangsan');
+
+```
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/10tx11y-1.webp)
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/10u159n-1.webp)
+
+
+```sql
+show engine innodb status;
+```
+
+
+经典“交叉持锁、互等”死锁：
+事务 (1) 当前语句是 select * from deadlock_test where id = 1 for update，日志显示它已持有 id=2 的记录锁，正等待获取 id=1 的锁。
+事务 (2) 当前语句是 select * from deadlock_test where id = 2 for update，日志显示它已持有 id=1 的记录锁，正等待获取 id=2 的锁。
+二者形成环：T1 持 id=2 等 id=1；T2 持 id=1 等 id=2。
+锁类型：lock_mode X locks rec but not gap 为记录级行锁（非 GAP 锁），锁定的是主键记录本身。
+仲裁结果：InnoDB 回滚了事务 (2)（“WE ROLL BACK TRANSACTION (2)”），说明它评估回滚成本更低（未必是开始时间靠后）。
+
+```
+------------------------
+LATEST DETECTED DEADLOCK
+------------------------
+2025-09-08 14:25:29 138110019045056
+*** (1) TRANSACTION:
+TRANSACTION 48777, ACTIVE 96 sec starting index read
+mysql tables in use 1, locked 1
+LOCK WAIT 3 lock struct(s), heap size 1128, 2 row lock(s), undo log entries 1
+MySQL thread id 638, OS thread handle 138111594002112, query id 479129 10.0.0.8 root statistics
+select * from deadlock_test where id = 1 for update
+
+*** (1) HOLDS THE LOCK(S):
+RECORD LOCKS space id 76 page no 4 n bits 72 index PRIMARY of table `deadlock`.`deadlock_test` trx id 48777 lock_mode X locks rec but not gap
+Record lock, heap no 3 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
+ 0: len 8; hex 8000000000000002; asc         ;;
+ 1: len 6; hex 00000000be89; asc       ;;
+ 2: len 7; hex 82000001230110; asc     #  ;;
+ 3: len 7; hex 77616e6773616e; asc wangsan;;
+
+
+*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
+RECORD LOCKS space id 76 page no 4 n bits 72 index PRIMARY of table `deadlock`.`deadlock_test` trx id 48777 lock_mode X locks rec but not gap waiting
+Record lock, heap no 2 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
+ 0: len 8; hex 8000000000000001; asc         ;;
+ 1: len 6; hex 00000000be80; asc       ;;
+ 2: len 7; hex 01000000be2b14; asc      + ;;
+ 3: len 4; hex 6c697369; asc lisi;;
+
+
+*** (2) TRANSACTION:
+TRANSACTION 48768, ACTIVE 149 sec starting index read
+mysql tables in use 1, locked 1
+LOCK WAIT 3 lock struct(s), heap size 1128, 2 row lock(s), undo log entries 1
+MySQL thread id 636, OS thread handle 138111598196416, query id 479151 10.0.0.8 root statistics
+select * from deadlock_test where id = 2 for update
+
+*** (2) HOLDS THE LOCK(S):
+RECORD LOCKS space id 76 page no 4 n bits 72 index PRIMARY of table `deadlock`.`deadlock_test` trx id 48768 lock_mode X locks rec but not gap
+Record lock, heap no 2 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
+ 0: len 8; hex 8000000000000001; asc         ;;
+ 1: len 6; hex 00000000be80; asc       ;;
+ 2: len 7; hex 01000000be2b14; asc      + ;;
+ 3: len 4; hex 6c697369; asc lisi;;
+
+
+*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
+RECORD LOCKS space id 76 page no 4 n bits 72 index PRIMARY of table `deadlock`.`deadlock_test` trx id 48768 lock_mode X locks rec but not gap waiting
+Record lock, heap no 3 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
+ 0: len 8; hex 8000000000000002; asc         ;;
+ 1: len 6; hex 00000000be89; asc       ;;
+ 2: len 7; hex 82000001230110; asc     #  ;;
+ 3: len 7; hex 77616e6773616e; asc wangsan;;
+
+*** WE ROLL BACK TRANSACTION (2)
+------------
+TRANSACTIONS
+------------
+Trx id counter 48783
+Purge done for trx's n:o < 48783 undo n:o < 0 state: running but idle
+History list length 1
+LIST OF TRANSACTIONS FOR EACH SESSION:
+---TRANSACTION 419586600079360, not started
+0 lock struct(s), heap size 1128, 0 row lock(s)
+---TRANSACTION 419586600080976, not started
+0 lock struct(s), heap size 1128, 0 row lock(s)
+---TRANSACTION 419586600080168, not started
+0 lock struct(s), heap size 1128, 0 row lock(s)
+---TRANSACTION 419586600078552, not started
+0 lock struct(s), heap size 1128, 0 row lock(s)
+---TRANSACTION 419586600077744, not started
+0 lock struct(s), heap size 1128, 0 row lock(s)
+---TRANSACTION 419586600076936, not started
+0 lock struct(s), heap size 1128, 0 row lock(s)
+---TRANSACTION 48777, ACTIVE 121 sec
+5 lock struct(s), heap size 1128, 2 row lock(s), undo log entries 1
+MySQL thread id 638, OS thread handle 138111594002112, query id 479167 10.0.0.8 root
+```
+
+通过MySQL系统库查询被阻塞的事务以及线程ID，手动kill释放资源
+
+查询锁信息表：
+```sql
+-- 8.0 版本以前
+select * from information_schema.innodb_locks;
+-- 8.0版本开始
+select * from performance_schema.data_locks;
+```
+
+## 关闭死锁检测
+```sql
+SHOW VARIABLES LIKE 'innodb_deadlock_detect';
+```
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/110r5za-1.webp)
+
+
+```sql
+
+SET GLOBAL innodb_deadlock_detect = 0;
+```
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/111e4i9-1.webp)
+
+
+接下来我们再次开两个事务
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/112zyds-1.webp)
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/11321yv-1.webp)
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/114vhsk-1.webp)
+
+
+查询锁等待信息表
+```sql
+-- 8.0版本之前
+select * from information_schema.innodb_lock_waits;
+-- 8.0版本开始
+select * from performance_schema.data_lock_waits;
+```
+![](https://blog.meowrain.cn/api/i/2025/09/08/114xwmu-1.webp)
+![](https://blog.meowrain.cn/api/i/2025/09/08/115w1hh-1.webp)
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/116hus4-1.webp)
+
+查询innodb事务信息
+```sql
+SELECT * from information_schema.INNODB_TRX;
+
+```
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/11a35ow-1.webp)
+
+
+![](https://blog.meowrain.cn/api/i/2025/09/08/118hy05-1.webp)
+![](https://blog.meowrain.cn/api/i/2025/09/08/118d2ss-1.webp)
+![](https://blog.meowrain.cn/api/i/2025/09/08/118f5gd-1.webp)
+![](https://blog.meowrain.cn/api/i/2025/09/08/118gs9v-1.webp)
+
+
+
+```sql
+-- 列出当前的阻塞者（含可直接 KILL 的进程号）
+SELECT
+  b.ENGINE_TRANSACTION_ID   AS blocking_trx_id,
+  th.PROCESSLIST_ID         AS blocking_pid,
+  trx.trx_started,
+  trx.trx_state,
+  trx.trx_rows_locked,
+  trx.trx_query
+FROM performance_schema.data_lock_waits w
+JOIN performance_schema.data_locks b
+  ON w.blocking_engine_lock_id = b.engine_lock_id
+JOIN information_schema.INNODB_TRX trx
+  ON b.engine_transaction_id = trx.trx_id
+JOIN performance_schema.threads th
+  ON b.thread_id = th.thread_id
+GROUP BY blocking_trx_id, blocking_pid, trx.trx_started, trx.trx_state, trx.trx_rows_locked, trx.trx_query;
+
+-- 杀掉阻塞会话
+KILL CONNECTION <blocking_pid>;
+```
+![](https://blog.meowrain.cn/api/i/2025/09/08/119g2ic-1.webp)
+