MySQL 8.4 发行说明
互斥锁是一种在代码中使用的同步机制，用于确保在给定时间只有一个线程可以访问公共资源。当服务器中执行的两个或多个线程需要访问同一资源时，这些线程就会相互竞争。第一个获取互斥锁的线程会导致其他线程等待，直到该锁被释放。
对于已进行检测的 InnoDB 互斥锁，可以使用 性能模式 监控互斥锁等待。例如，性能模式表中收集的等待事件数据可以帮助识别等待次数最多或总等待时间最长的互斥锁。
以下示例演示了如何启用 InnoDB 互斥锁等待检测工具、如何启用关联的消费者以及如何查询等待事件数据。
要查看可用的
InnoDB互斥锁等待检测工具，请查询性能模式setup_instruments表。默认情况下，所有InnoDB互斥锁等待检测工具都被禁用。mysql> SELECT * FROM performance_schema.setup_instruments WHERE NAME LIKE '%wait/synch/mutex/innodb%'; +---------------------------------------------------------+---------+-------+ | NAME | ENABLED | TIMED | +---------------------------------------------------------+---------+-------+ | wait/synch/mutex/innodb/commit_cond_mutex | NO | NO | | wait/synch/mutex/innodb/innobase_share_mutex | NO | NO | | wait/synch/mutex/innodb/autoinc_mutex | NO | NO | | wait/synch/mutex/innodb/autoinc_persisted_mutex | NO | NO | | wait/synch/mutex/innodb/buf_pool_flush_state_mutex | NO | NO | | wait/synch/mutex/innodb/buf_pool_LRU_list_mutex | NO | NO | | wait/synch/mutex/innodb/buf_pool_free_list_mutex | NO | NO | | wait/synch/mutex/innodb/buf_pool_zip_free_mutex | NO | NO | | wait/synch/mutex/innodb/buf_pool_zip_hash_mutex | NO | NO | | wait/synch/mutex/innodb/buf_pool_zip_mutex | NO | NO | | wait/synch/mutex/innodb/cache_last_read_mutex | NO | NO | | wait/synch/mutex/innodb/dict_foreign_err_mutex | NO | NO | | wait/synch/mutex/innodb/dict_persist_dirty_tables_mutex | NO | NO | | wait/synch/mutex/innodb/dict_sys_mutex | NO | NO | | wait/synch/mutex/innodb/recalc_pool_mutex | NO | NO | | wait/synch/mutex/innodb/fil_system_mutex | NO | NO | | wait/synch/mutex/innodb/flush_list_mutex | NO | NO | | wait/synch/mutex/innodb/fts_bg_threads_mutex | NO | NO | | wait/synch/mutex/innodb/fts_delete_mutex | NO | NO | | wait/synch/mutex/innodb/fts_optimize_mutex | NO | NO | | wait/synch/mutex/innodb/fts_doc_id_mutex | NO | NO | | wait/synch/mutex/innodb/log_flush_order_mutex | NO | NO | | wait/synch/mutex/innodb/hash_table_mutex | NO | NO | | wait/synch/mutex/innodb/ibuf_bitmap_mutex | NO | NO | | wait/synch/mutex/innodb/ibuf_mutex | NO | NO | | wait/synch/mutex/innodb/ibuf_pessimistic_insert_mutex | NO | NO | | wait/synch/mutex/innodb/log_sys_mutex | NO | NO | | wait/synch/mutex/innodb/log_sys_write_mutex | NO | NO | | wait/synch/mutex/innodb/mutex_list_mutex | NO | NO | | wait/synch/mutex/innodb/page_zip_stat_per_index_mutex | NO | NO | | wait/synch/mutex/innodb/purge_sys_pq_mutex | NO | NO | | wait/synch/mutex/innodb/recv_sys_mutex | NO | NO | | wait/synch/mutex/innodb/recv_writer_mutex | NO | NO | | wait/synch/mutex/innodb/redo_rseg_mutex | NO | NO | | wait/synch/mutex/innodb/noredo_rseg_mutex | NO | NO | | wait/synch/mutex/innodb/rw_lock_list_mutex | NO | NO | | wait/synch/mutex/innodb/rw_lock_mutex | NO | NO | | wait/synch/mutex/innodb/srv_dict_tmpfile_mutex | NO | NO | | wait/synch/mutex/innodb/srv_innodb_monitor_mutex | NO | NO | | wait/synch/mutex/innodb/srv_misc_tmpfile_mutex | NO | NO | | wait/synch/mutex/innodb/srv_monitor_file_mutex | NO | NO | | wait/synch/mutex/innodb/buf_dblwr_mutex | NO | NO | | wait/synch/mutex/innodb/trx_undo_mutex | NO | NO | | wait/synch/mutex/innodb/trx_pool_mutex | NO | NO | | wait/synch/mutex/innodb/trx_pool_manager_mutex | NO | NO | | wait/synch/mutex/innodb/srv_sys_mutex | NO | NO | | wait/synch/mutex/innodb/lock_mutex | NO | NO | | wait/synch/mutex/innodb/lock_wait_mutex | NO | NO | | wait/synch/mutex/innodb/trx_mutex | NO | NO | | wait/synch/mutex/innodb/srv_threads_mutex | NO | NO | | wait/synch/mutex/innodb/rtr_active_mutex | NO | NO | | wait/synch/mutex/innodb/rtr_match_mutex | NO | NO | | wait/synch/mutex/innodb/rtr_path_mutex | NO | NO | | wait/synch/mutex/innodb/rtr_ssn_mutex | NO | NO | | wait/synch/mutex/innodb/trx_sys_mutex | NO | NO | | wait/synch/mutex/innodb/zip_pad_mutex | NO | NO | | wait/synch/mutex/innodb/master_key_id_mutex | NO | NO | +---------------------------------------------------------+---------+-------+一些
InnoDB互斥锁实例是在服务器启动时创建的，并且只有在服务器启动时也启用了关联的检测工具的情况下才会对其进行检测。要确保对所有InnoDB互斥锁实例进行检测和启用，请将以下performance-schema-instrument规则添加到您的 MySQL 配置文件中performance-schema-instrument='wait/synch/mutex/innodb/%=ON'如果不需要所有
InnoDB互斥锁的等待事件数据，可以通过在 MySQL 配置文件中添加其他performance-schema-instrument规则来禁用特定的检测工具。例如，要禁用与全文搜索相关的InnoDB互斥锁等待事件检测工具，请添加以下规则performance-schema-instrument='wait/synch/mutex/innodb/fts%=OFF'注意具有较长前缀的规则（如
wait/synch/mutex/innodb/fts%）优先于具有较短前缀的规则（如wait/synch/mutex/innodb/%）。将
performance-schema-instrument规则添加到配置文件后，请重新启动服务器。除了与全文搜索相关的InnoDB互斥锁之外，所有其他互斥锁都将被启用。要进行验证，请查询setup_instruments表。对于您启用的检测工具，ENABLED和TIMED列应设置为YES。mysql> SELECT * FROM performance_schema.setup_instruments WHERE NAME LIKE '%wait/synch/mutex/innodb%'; +-------------------------------------------------------+---------+-------+ | NAME | ENABLED | TIMED | +-------------------------------------------------------+---------+-------+ | wait/synch/mutex/innodb/commit_cond_mutex | YES | YES | | wait/synch/mutex/innodb/innobase_share_mutex | YES | YES | | wait/synch/mutex/innodb/autoinc_mutex | YES | YES | ... | wait/synch/mutex/innodb/master_key_id_mutex | YES | YES | +-------------------------------------------------------+---------+-------+ 49 rows in set (0.00 sec)通过更新
setup_consumers表来启用等待事件消费者。默认情况下，等待事件消费者是被禁用的。mysql> UPDATE performance_schema.setup_consumers SET enabled = 'YES' WHERE name like 'events_waits%'; Query OK, 3 rows affected (0.00 sec) Rows matched: 3 Changed: 3 Warnings: 0您可以通过查询
setup_consumers表来验证等待事件消费者是否已启用。events_waits_current、events_waits_history和events_waits_history_long消费者应该被启用。mysql> SELECT * FROM performance_schema.setup_consumers; +----------------------------------+---------+ | NAME | ENABLED | +----------------------------------+---------+ | events_stages_current | NO | | events_stages_history | NO | | events_stages_history_long | NO | | events_statements_current | YES | | events_statements_history | YES | | events_statements_history_long | NO | | events_transactions_current | YES | | events_transactions_history | YES | | events_transactions_history_long | NO | | events_waits_current | YES | | events_waits_history | YES | | events_waits_history_long | YES | | global_instrumentation | YES | | thread_instrumentation | YES | | statements_digest | YES | +----------------------------------+---------+ 15 rows in set (0.00 sec)启用检测工具和消费者后，运行您要监控的工作负载。在此示例中，使用 mysqlslap 负载仿真客户端来模拟工作负载。
$> ./mysqlslap --auto-generate-sql --concurrency=100 --iterations=10 --number-of-queries=1000 --number-char-cols=6 --number-int-cols=6;查询等待事件数据。在本例中，等待事件数据是从
events_waits_summary_global_by_event_name表中查询的，该表汇总了events_waits_current、events_waits_history和events_waits_history_long表中的数据。数据按事件名称（EVENT_NAME）汇总，该名称是生成事件的工具的名称。汇总数据包括COUNT_STAR汇总的等待事件的数量。
SUM_TIMER_WAIT汇总的定时等待事件的总等待时间。
MIN_TIMER_WAIT汇总的定时等待事件的最短等待时间。
AVG_TIMER_WAIT汇总的定时等待事件的平均等待时间。
MAX_TIMER_WAIT汇总的定时等待事件的最长等待时间。
以下查询返回工具名称（
EVENT_NAME）、等待事件的数量（COUNT_STAR）以及该工具的事件的总等待时间（SUM_TIMER_WAIT）。由于默认情况下等待时间以皮秒（万亿分之一秒）计时，因此将等待时间除以 1000000000 以毫秒为单位显示等待时间。数据按汇总的等待事件的数量（COUNT_STAR）降序显示。您可以调整ORDER BY子句以按总等待时间对数据进行排序。mysql> SELECT EVENT_NAME, COUNT_STAR, SUM_TIMER_WAIT/1000000000 SUM_TIMER_WAIT_MS FROM performance_schema.events_waits_summary_global_by_event_name WHERE SUM_TIMER_WAIT > 0 AND EVENT_NAME LIKE 'wait/synch/mutex/innodb/%' ORDER BY COUNT_STAR DESC; +---------------------------------------------------------+------------+-------------------+ | EVENT_NAME | COUNT_STAR | SUM_TIMER_WAIT_MS | +---------------------------------------------------------+------------+-------------------+ | wait/synch/mutex/innodb/trx_mutex | 201111 | 23.4719 | | wait/synch/mutex/innodb/fil_system_mutex | 62244 | 9.6426 | | wait/synch/mutex/innodb/redo_rseg_mutex | 48238 | 3.1135 | | wait/synch/mutex/innodb/log_sys_mutex | 46113 | 2.0434 | | wait/synch/mutex/innodb/trx_sys_mutex | 35134 | 1068.1588 | | wait/synch/mutex/innodb/lock_mutex | 34872 | 1039.2589 | | wait/synch/mutex/innodb/log_sys_write_mutex | 17805 | 1526.0490 | | wait/synch/mutex/innodb/dict_sys_mutex | 14912 | 1606.7348 | | wait/synch/mutex/innodb/trx_undo_mutex | 10634 | 1.1424 | | wait/synch/mutex/innodb/rw_lock_list_mutex | 8538 | 0.1960 | | wait/synch/mutex/innodb/buf_pool_free_list_mutex | 5961 | 0.6473 | | wait/synch/mutex/innodb/trx_pool_mutex | 4885 | 8821.7496 | | wait/synch/mutex/innodb/buf_pool_LRU_list_mutex | 4364 | 0.2077 | | wait/synch/mutex/innodb/innobase_share_mutex | 3212 | 0.2650 | | wait/synch/mutex/innodb/flush_list_mutex | 3178 | 0.2349 | | wait/synch/mutex/innodb/trx_pool_manager_mutex | 2495 | 0.1310 | | wait/synch/mutex/innodb/buf_pool_flush_state_mutex | 1318 | 0.2161 | | wait/synch/mutex/innodb/log_flush_order_mutex | 1250 | 0.0893 | | wait/synch/mutex/innodb/buf_dblwr_mutex | 951 | 0.0918 | | wait/synch/mutex/innodb/recalc_pool_mutex | 670 | 0.0942 | | wait/synch/mutex/innodb/dict_persist_dirty_tables_mutex | 345 | 0.0414 | | wait/synch/mutex/innodb/lock_wait_mutex | 303 | 0.1565 | | wait/synch/mutex/innodb/autoinc_mutex | 196 | 0.0213 | | wait/synch/mutex/innodb/autoinc_persisted_mutex | 196 | 0.0175 | | wait/synch/mutex/innodb/purge_sys_pq_mutex | 117 | 0.0308 | | wait/synch/mutex/innodb/srv_sys_mutex | 94 | 0.0077 | | wait/synch/mutex/innodb/ibuf_mutex | 22 | 0.0086 | | wait/synch/mutex/innodb/recv_sys_mutex | 12 | 0.0008 | | wait/synch/mutex/innodb/srv_innodb_monitor_mutex | 4 | 0.0009 | | wait/synch/mutex/innodb/recv_writer_mutex | 1 | 0.0005 | +---------------------------------------------------------+------------+-------------------+注意前面的结果集包括启动过程中产生的等待事件数据。要排除此数据，您可以在启动后和运行工作负载之前立即截断
events_waits_summary_global_by_event_name表。但是，截断操作本身可能会产生可忽略不计的等待事件数据量。mysql> TRUNCATE performance_schema.events_waits_summary_global_by_event_name;