系统表介绍
memory_summary_by_thread_by_event_name 记录了事件对内存的使用,按照线程与事件进行分组统计.
| 列名 | 含义 |
|---|---|
| THREAD_ID | 线程编号 |
| EVENT_NAME | 事件名 |
| COUNT_ALLOC | 内存分配次数 |
| COUNT_FREE | 内存释放次数 |
| SUM_NUMBER_OF_BYTES_ALLOC | 总内存分配大小 |
| SUM_NUMBER_OF_BYTES_FREE | 总内存释放大小 |
| LOW_COUNT_USED | 当前持有的内存块数量 |
| CURRENT_COUNT_USED | 持有内存块的低水位线 |
| HIGH_COUNT_USED | 持有内存块的高水位线 |
| LOW_NUMBER_OF_BYTES_USED | 持有内存字节数的低水位线 |
| CURRENT_NUMBER_OF_BYTES_USED | 当前持有内存的数量 |
| HIGH_NUMBER_OF_BYTES_USED | 持有内存字节数的高水位线 |
实例
mysql> select * from memory_summary_by_thread_by_event_name order by CURRENT_NUMBER_OF_BYTES_USED desc limit 2 \G;
*************************** 1. row ***************************
THREAD_ID: 394
EVENT_NAME: memory/mysys/IO_CACHE
COUNT_ALLOC: 9
COUNT_FREE: 6
SUM_NUMBER_OF_BYTES_ALLOC: 196632
SUM_NUMBER_OF_BYTES_FREE: 131088
LOW_COUNT_USED: 0
CURRENT_COUNT_USED: 3
HIGH_COUNT_USED: 3
LOW_NUMBER_OF_BYTES_USED: 0
CURRENT_NUMBER_OF_BYTES_USED: 65544
HIGH_NUMBER_OF_BYTES_USED: 65544
*************************** 2. row ***************************
THREAD_ID: 394
EVENT_NAME: memory/sql/String::value
COUNT_ALLOC: 268
COUNT_FREE: 265
SUM_NUMBER_OF_BYTES_ALLOC: 37112
SUM_NUMBER_OF_BYTES_FREE: 20712
LOW_COUNT_USED: 0
CURRENT_COUNT_USED: 3
HIGH_COUNT_USED: 5
LOW_NUMBER_OF_BYTES_USED: 0
CURRENT_NUMBER_OF_BYTES_USED: 16400
HIGH_NUMBER_OF_BYTES_USED: 32784
2 rows in set (0.01 sec)