InnoDB 使用争用感知事务调度（CATS）算法来优先处理正在等待锁的事务。当多个事务在等待同一对象的锁时，CATS 算法决定哪个事务先获得锁。InnoDB uses the Contention-Aware Transaction Scheduling (CATS) algorithm to prioritize transactions that are waiting for locks. When multiple transactions are waiting for a lock on the same object, the CATS algorithm determines which transaction receives the lock first.

CATS 算法通过分配调度权重来优先处理等待事务，该权重是根据事务阻塞的事务数量计算的。例如，如果两个事务在等待同一对象的锁，阻塞其他事务最多的事务会被分配更高的调度权重。如果权重相等，则优先处理等待时间最长的事务。The CATS algorithm prioritizes waiting transactions by assigning a scheduling weight, which is computed based on the number of transactions that a transaction blocks. For example, if two transactions are waiting for a lock on the same object, the transaction that blocks the most transactions is assigned a greater scheduling weight. If weights are equal, priority is given to the longest waiting transaction.

您可以通过查询信息模式 INNODB_TRX 表中的 TRX_SCHEDULE_WEIGHT 列来查看事务调度权重。权重仅针对等待中的事务进行计算。等待中的事务是指处于 LOCK WAIT 事务执行状态的事务，如 TRX_STATE 列所报告的那样。未等待锁的事务报告的 TRX_SCHEDULE_WEIGHT 值为 NULL。You can view transaction scheduling weights by querying the TRX_SCHEDULE_WEIGHT column in the Information Schema INNODB_TRX table. Weights are computed for waiting transactions only. Waiting transactions are those in a LOCK WAIT transaction execution state, as reported by the TRX_STATE column. A transaction that is not waiting for a lock reports a NULL TRX_SCHEDULE_WEIGHT value.

INNODB_METRICS 计数器用于监控代码级事务调度事件。有关使用 INNODB_METRICS 计数器的信息，请参见 第 17.15.6 节，“InnoDB INFORMATION_SCHEMA Metrics 表”。INNODB_METRICS counters are provided for monitoring of code-level transaction scheduling events. For information about using INNODB_METRICS counters, see Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table”.