日韩性视频-久久久蜜桃-www中文字幕-在线中文字幕av-亚洲欧美一区二区三区四区-撸久久-香蕉视频一区-久久无码精品丰满人妻-国产高潮av-激情福利社-日韩av网址大全-国产精品久久999-日本五十路在线-性欧美在线-久久99精品波多结衣一区-男女午夜免费视频-黑人极品ⅴideos精品欧美棵-人人妻人人澡人人爽精品欧美一区-日韩一区在线看-欧美a级在线免费观看

          
    
          
        
          歡迎訪問 生活随笔！
          
        
          
            
            
        
          
        
          
        
          
            
          生活随笔
          
            
            
        
          
    
          
    
          
    
          
    
          
        
          
            
          
                
                    當前位置：
                    首頁 >
                            运维知识
>                            数据库
>内容正文                
                        
          数据库
          
            
          
                    
          
                        
          MySQL死锁案例分:先delete，再insert，导致死锁
          
                        
          
                            發(fā)布時間：2024/1/17
                            
 数据库                             
                            
                                27
                            
                            豆豆
                        
          
                        
          
                                                            生活随笔
收集整理的這篇文章主要介紹了
                                MySQL死锁案例分:先delete，再insert，导致死锁
小編覺得挺不錯的,現(xiàn)在分享給大家,幫大家做個參考.                        
          
                                
          
                                    



                                
          
                        
          
                            
                            
                            
          一、死鎖案例
           

          MySQL版本：Percona MySQL Server 5.7.19
           隔離級別：可重復讀（RR）
           業(yè)務邏輯：并發(fā)下按某個索引字段先delete記錄，再insert記錄
           

          比如：
           
begin;
delete from tb where order_id = xxx;
insert into tb(order_id) values(xxx);
commit;
 

          二、MySQL鎖基本概念
           

          S：共享鎖（行級鎖）
           X：排他鎖（行級鎖）
           IS：意向共享鎖（表級鎖）
           IX：意向排他鎖（表級鎖）
           

          以上4種鎖的兼容性見下表：
           


          鎖模式兼容性表
           

          • gap鎖與gap鎖之間不沖突
          • rec insert intention(插入意向鎖）與gap鎖沖突。
          

          三、模擬復現(xiàn)死鎖
           

          打開參數(shù)，從innodb status獲取更多的鎖信息。
           set GLOBAL innodb_status_output_locks=ON;
           

          表結構：
           
 CREATE TABLE `tb` (`order_id` int(11) DEFAULT NULL,KEY `idx_order_id` (`order_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
 

          表中數(shù)據(jù)：
           
mysql> select * from tb;
+----------+
| order_id |
+----------+
|       10 |
|       20 |
+----------+
2 rows in set (0.00 sec)
 

          事務執(zhí)行步驟：
           
session1session2
          begin?
          ?begin
          delete from tb where order_id=15;?
          ?delete from tb where order_id=15;
          ?insert into tb select 15;(等待鎖)
          insert into tb select 15;(死鎖)?
          

        1. 當session1執(zhí)行delete from tb where order_id=15;，由于條件order_id=15的記錄不存在，session1 獲得2個鎖結構，分別是意向排他鎖IX（表級鎖）、gap鎖（行級鎖），如下：
          2. 
---TRANSACTION 1055191443, ACTIVE 20 sec
2 lock struct(s), heap size 1136, 1 row lock(s)
MySQL thread id 315642, OS thread handle 139960342456064, query id 150462030 localhost root
TABLE LOCK table `db`.`tb` trx id 1055191443 lock mode IX
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191443 lock_mode X locks gap before rec
 

        2. 當session2執(zhí)行delete from tb where order_id=15;，同樣由于order_id=15的記錄不存在，session2 也獲得2個鎖結構，分別是意向排他鎖IX（表級鎖）、gap鎖（行級鎖），如下：
          3. 
---TRANSACTION 1055191444, ACTIVE 3 sec
2 lock struct(s), heap size 1136, 1 row lock(s)
MySQL thread id 315336, OS thread handle 139960562685696, query id 150462412 localhost root
TABLE LOCK table `db`.`tb` trx id 1055191444 lock mode IX
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191444 lock_mode X locks gap before rec
 

        3. 當session2執(zhí)行insert into tb select 15;， session2 已經(jīng)獲取到IX鎖，gap鎖，等待 rec insert intention（插入意向鎖）
          4. 
---TRANSACTION 1055191444, ACTIVE 68 sec inserting
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 1136, 2 row lock(s), undo log entries 1
MySQL thread id 315336, OS thread handle 139960562685696, query id 150462778 localhost root executing
insert into tb select 15
------- TRX HAS BEEN WAITING 2 SEC FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191444 lock_mode X locks gap before rec insert intention waiting
------------------
TABLE LOCK table `db`.`tb` trx id 1055191444 lock mode IX
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191444 lock_mode X locks gap before rec
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191444 lock_mode X locks gap before rec insert intention waiting
 

        4. 當session1執(zhí)行insert into tb select 15;，session1 已獲取到IX鎖，gap鎖， 等待rec insert intention（插入意向鎖）， session1, session2 都在等待插入意向鎖， 插入意向鎖與gap鎖沖突，雙方都沒有釋放gap鎖，又都在等待插入意向鎖，死鎖發(fā)生。
          5. 
LATEST DETECTED DEADLOCK
------------------------
2018-11-03 17:15:11 0x7f4b0e7ea700
*** (1) TRANSACTION:
TRANSACTION 1055191444, ACTIVE 135 sec inserting
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 1136, 2 row lock(s), undo log entries 1
MySQL thread id 315336, OS thread handle 139960562685696, query id 150462778 localhost root executing
insert into tb select 15
*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191444 lock_mode X locks gap before rec insert intention waiting
*** (2) TRANSACTION:
TRANSACTION 1055191443, ACTIVE 201 sec inserting, thread declared inside InnoDB 5000
mysql tables in use 1, locked 1
3 lock struct(s), heap size 1136, 2 row lock(s), undo log entries 1
MySQL thread id 315642, OS thread handle 139960342456064, query id 150463172 localhost root executing
insert into tb select 15
*** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191443 lock_mode X locks gap before rec
*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191443 lock_mode X locks gap before rec insert intention waiting
*** WE ROLL BACK TRANSACTION (2)
 

          四、案例擴展
           

          以上死鎖案例，業(yè)務代碼邏輯是多線程并發(fā)下，有可能多個線程會執(zhí)行相同order_id的job，比如兩個線程執(zhí)行的order_id 都是15。
           另外一種情況，多個線程間，不會執(zhí)行到相同order_id的情況，也可能發(fā)生死鎖。比如一個線程order_id=15，另外一個線程order_id=16，如下所示：
           

          事務執(zhí)行步驟：
           
session1session2
          begin?
          ?begin
          delete from tb where order_id=15;?
          ?delete from tb where order_id=16;
          ?insert into tb select 16;(等待鎖)
          insert into tb select 15;(死鎖)?
          

          鎖情況與上述相同，不再贅述，死鎖信息如下：
           
LATEST DETECTED DEADLOCK
------------------------
2018-11-03 17:28:30 0x7f4b0e667700
*** (1) TRANSACTION:
TRANSACTION 1055191450, ACTIVE 18 sec inserting
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 1136, 2 row lock(s), undo log entries 1
MySQL thread id 316221, OS thread handle 139960338228992, query id 150467652 localhost root executing
insert into tb select 16
*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191450 lock_mode X locks gap before rec insert intention waiting
*** (2) TRANSACTION:
TRANSACTION 1055191449, ACTIVE 28 sec inserting, thread declared inside InnoDB 5000
mysql tables in use 1, locked 1
3 lock struct(s), heap size 1136, 2 row lock(s), undo log entries 1
MySQL thread id 316222, OS thread handle 139960340870912, query id 150467681 localhost root executing
insert into tb select 15
*** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191449 lock_mode X locks gap before rec
*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 1337 page no 4 n bits 72 index idx_order_id of table `db`.`tb` trx id 1055191449 lock_mode X locks gap before rec insert intention waiting
*** WE ROLL BACK TRANSACTION (2) 

          五、解決方案
           

        5. 修改隔離級別為提交讀（RC）
        6. 修改業(yè)務代碼邏輯，刪除記錄之前，先select，確認該記錄存在，再執(zhí)行delete刪除該記錄。
          7. 
                            
          總結
          
                            
          
                                以上是生活随笔為你收集整理的MySQL死锁案例分:先delete，再insert，导致死锁的全部內容，希望文章能夠幫你解決所遇到的問題。
                            
          
                            
          
                                如果覺得生活随笔網(wǎng)站內容還不錯，歡迎將生活随笔推薦給好友。