***(1) TRANSACTION: TRANSACTION 0 677833455, ACTIVE 0 sec, process no 11393, OS thread id 278546 starting index read mysql tables in use 1, locked 1 LOCK WAIT 3 lock struct(s), heap size 320 MySQL thread id 83, query id 162348740 dcnet03 dcnet Searching rows for update update tab_test set state=1064,time=now() where state=1061 and time < date_sub(now(), INTERVAL 30 minute) (任务1的sql语句) ***(1) WAITING FOR THIS LOCK TO BE GRANTED: (任务1等待的索引记录) RECORD LOCKS space id 0 page no 849384 n bits 208 index `PRIMARY` of table `db/tab_test` trx id 0 677833455 _mode X locks rec but not gap waiting Record lock, heap no 92 PHYSICAL RECORD: n_fields 11; compact format; info bits 0 0: len 8; hex 800000000097629c; asc b ;; 1: len 6; hex 00002866eaee; asc (f ;; 2: len 7; hex 00000d40040110; asc @ ;; 3: len 8; hex 80000000000050b2; asc P ;; 4: len 8; hex 800000000000502a; asc P*;; 5: len 8; hex 8000000000005426; asc T&;; 6: len 8; hex 800012412c66d29c; asc A,f ;; 7: len 23; hex 75706c6f6164666972652e636f6d2f6 8616e642e706870; asc xxx.com/;; 8: len 8; hex 800000000000042b; asc +;; 9: len 4; hex 474bfa2b; asc GK +;; 10: len 8; hex 8000000000004e24; asc N$;; *** (2) TRANSACTION: TRANSACTION 0 677833454, ACTIVE 0 sec, process no 11397, OS thread id 344086 updating or deleting, thread declared inside InnoDB 499 mysql tables in use 1, locked 1 3 lock struct(s), heap size 320, undo log entries 1 MySQL thread id 84, query id 162348739 dcnet03 dcnet Updating update tab_test set state=1067,time=now () where id in (9921180) (任务2的sql语句) *** (2) HOLDS THE LOCK(S): (任务2已获得的锁) RECORD LOCKS space id 0 page no 849384 n bits 208 index `PRIMARY` of table `db/tab_test` trx id 0 677833454 lock_mode X locks rec but not gap Record lock, heap no 92 PHYSICAL RECORD: n_fields 11; compact format; info bits 0 0: len 8; hex 800000000097629c; asc b ;; 1: len 6; hex 00002866eaee; asc (f ;; 2: len 7; hex 00000d40040110; asc @ ;; 3: len 8; hex 80000000000050b2; asc P ;; 4: len 8; hex 800000000000502a; asc P*;; 5: len 8; hex 8000000000005426; asc T&;; 6: len 8; hex 800012412c66d29c; asc A,f ;; 7: len 23; hex 75706c6f6164666972652e636f6d2f6 8616e642e706870; asc uploadfire.com/hand.php;; 8: len 8; hex 800000000000042b; asc +;; 9: len 4; hex 474bfa2b; asc GK +;; 10: len 8; hex 8000000000004e24; asc N$;; *** (2) WAITING FOR THIS LOCK TO BE GRANTED: (任务2等待的锁) RECORD LOCKS space id 0 page no 843102 n bits 600 index `idx_1` of table `db/tab_test` trx id 0 677833454 lock_mode X locks rec but not gap waiting Record lock, heap no 395 PHYSICAL RECORD: n_fields 3; compact format; info bits 0 0: len 8; hex 8000000000000425; asc %;; 1: len 8; hex 800012412c66d29c; asc A,f ;; 2: len 8; hex 800000000097629c; asc b ;; *** WE ROLL BACK TRANSACTION (1) (回滚了任务1，以解除死锁)
原因分析：
当“update tab_test set state=1064,time=now() where state=1061 and time < date_sub(now(), INTERVAL 30 minute)”执行时，MySQL会使用idx_1索引，因此首先锁定相关的索引记录，因为idx_1是非主键索引，为执行该语句，MySQL还会锁定主键索引。
假设“update tab_test set state=1067,time=now () where id in (9921180)”几乎同时执行时，本语句首先锁定主键索引，由于需要更新state的值，所以还需要锁定idx_1的某些索引记录。
