MySQL :: MySQL 8.4 Reference Manual :: 10.12.3.2 Monitoring MySQL Memory Usage

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10.12.3.2 MySQL 内存使用情况监控

以下示例演示如何使用Performance Schema和sys schema监控MySQL内存使用情况。

大多数Performance Schema内存instrumentation默认处于禁用状态。可以通过更新Performance Schemasetup_instruments表的ENABLED列来启用instrumentation。内存instrumentation名称以memory/code_area/instrument_name的形式，where code_area是值如sql或innodb，and instrument_name是instrument detail。

要查看可用的MySQL内存instrumentation，可以查询Performance Schemasetup_instruments表。以下查询返回所有代码区域的数百个内存instrumentation。

mysql> SELECT * FROM performance_schema.setup_instruments
       WHERE NAME LIKE '%memory%';

可以通过指定代码区域来限制结果。例如，可以将结果限制到InnoDB内存instrumentation bằng cách指定innodb作为代码区域。

mysql> SELECT * FROM performance_schema.setup_instruments
       WHERE NAME LIKE '%memory/innodb%';
+-------------------------------------------+---------+-------+
| NAME                                      | ENABLED | TIMED |
+-------------------------------------------+---------+-------+
| memory/innodb/adaptive hash index         | NO      | NO    |
| memory/innodb/buf_buf_pool                | NO      | NO    |
| memory/innodb/dict_stats_bg_recalc_pool_t | NO      | NO    |
| memory/innodb/dict_stats_index_map_t      | NO      | NO    |
| memory/innodb/dict_stats_n_diff_on_level  | NO      | NO    |
| memory/innodb/other                       | NO      | NO    |
| memory/innodb/row_log_buf                 | NO      | NO    |
| memory/innodb/row_merge_sort              | NO      | NO    |
| memory/innodb/std                         | NO      | NO    |
| memory/innodb/trx_sys_t::rw_trx_ids       | NO      | NO    |
...

根据您的MySQL安装，代码区域可能包括performance_schema、sql、client、innodb、myisam、csv、memory、blackhole、archive、partition和其他。

要启用内存仪器，添加一个performance-schema-instrument规则到您的MySQL配置文件中。例如，要启用所有内存仪器，请将以下规则添加到您的配置文件并重新启动服务器：

performance-schema-instrument='memory/%=COUNTED'

Note

在启动时启用内存仪器确保了在启动时发生的内存分配被计数。

在重新启动服务器后，Performance Schema setup_instruments 表的ENABLED列应该报告内存仪器为YES。Performance Schema setup_instruments 表的TIMED列对于内存仪器被忽略，因为内存操作不被计时。

mysql> SELECT * FROM performance_schema.setup_instruments
       WHERE NAME LIKE '%memory/innodb%';
+-------------------------------------------+---------+-------+
| NAME                                      | ENABLED | TIMED |
+-------------------------------------------+---------+-------+
| memory/innodb/adaptive hash index         | NO      | NO    |
| memory/innodb/buf_buf_pool                | NO      | NO    |
| memory/innodb/dict_stats_bg_recalc_pool_t | NO      | NO    |
| memory/innodb/dict_stats_index_map_t      | NO      | NO    |
| memory/innodb/dict_stats_n_diff_on_level  | NO      | NO    |
| memory/innodb/other                       | NO      | NO    |
| memory/innodb/row_log_buf                 | NO      | NO    |
| memory/innodb/row_merge_sort              | NO      | NO    |
| memory/innodb/std                         | NO      | NO    |
| memory/innodb/trx_sys_t::rw_trx_ids       | NO      | NO    |
...

查询内存仪器数据。在这个示例中，内存仪器数据在Performance Schema memory_summary_global_by_event_name 表中查询，该表对数据进行了EVENT_NAME的总结。EVENT_NAME是仪器的名称。

以下查询返回InnoDB缓冲池的内存数据。关于列描述，请见第29.12.20.10节，“Memory Summary Tables”。

mysql> SELECT * FROM performance_schema.memory_summary_global_by_event_name
       WHERE EVENT_NAME LIKE 'memory/innodb/buf_buf_pool'\G
                  EVENT_NAME: memory/innodb/buf_buf_pool
                 COUNT_ALLOC: 1
                  COUNT_FREE: 0
   SUM_NUMBER_OF_BYTES_ALLOC: 137428992
    SUM_NUMBER_OF_BYTES_FREE: 0
              LOW_COUNT_USED: 0
          CURRENT_COUNT_USED: 1
             HIGH_COUNT_USED: 1
    LOW_NUMBER_OF_BYTES_USED: 0
CURRENT_NUMBER_OF_BYTES_USED: 137428992
   HIGH_NUMBER_OF_BYTES_USED: 137428992

使用同样的底层数据，可以通过sys架构的memory_global_by_current_bytes表，显示服务器全局的当前内存使用情况，按分配类型进行分类。

mysql> SELECT * FROM sys.memory_global_by_current_bytes
       WHERE event_name LIKE 'memory/innodb/buf_buf_pool'\G
*************************** 1. row ***************************
       event_name: memory/innodb/buf_buf_pool
    current_count: 1
    current_alloc: 131.06 MiB
current_avg_alloc: 131.06 MiB
       high_count: 1
       high_alloc: 131.06 MiB
   high_avg_alloc: 131.06 MiB

这个sys架构查询聚合了当前已分配内存(current_alloc)，按代码区域进行分类：

mysql> SELECT SUBSTRING_INDEX(event_name,'/',2) AS
       code_area, FORMAT_BYTES(SUM(current_alloc))
       AS current_alloc
       FROM sys.x$memory_global_by_current_bytes
       GROUP BY SUBSTRING_INDEX(event_name,'/',2)
       ORDER BY SUM(current_alloc) DESC;
+---------------------------+---------------+
| code_area                 | current_alloc |
+---------------------------+---------------+
| memory/innodb             | 843.24 MiB    |
| memory/performance_schema | 81.29 MiB     |
| memory/mysys              | 8.20 MiB      |
| memory/sql                | 2.47 MiB      |
| memory/memory             | 174.01 KiB    |
| memory/myisam             | 46.53 KiB     |
| memory/blackhole          | 512 bytes     |
| memory/federated          | 512 bytes     |
| memory/csv                | 512 bytes     |
| memory/vio                | 496 bytes     |
+---------------------------+---------------+

关于sys架构的更多信息，请见第30章，《MySQL sys Schema》。

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