MySQLTransactionRollbackException: Lock wait timeout exceeded； try restarting transaction

MySQLTransactionRollbackException: Lock wait timeout exceeded; try restarting transaction

笔者报错原因：
一次服务调用开启了两个事务
事务1先对表记录A上X锁，开始事务2，等待返回。
事务2要对记录A上S锁，等待，超时回滚报错。

#mysql查看事务，锁等待关系的sql
select * from information_schema.innodb_trx;
select * from information_schema.innodb_lock_waits;
select * from information_schema.innodb_locks;