PERFORMANCE_SCHEMA 詳解

http://keithlan.github.io/2015/07/17/22_performance_schema/

http://www.markleith.co.uk/

http://www.cnblogs.com/cchust/p/5022148.html?utm_source=tuicool&utm_medium=referral

 

MYSQL 是否支持 PERFORMANCE_SCHEMA 引擎

mysql> SELECT * FROM INFORMATION_SCHEMA.ENGINES ;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| ENGINE             | SUPPORT | COMMENT                                                        | TRANSACTIONS | XA   | SAVEPOINTS |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| BLACKHOLE          | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |
| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| FEDERATED          | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)

 

mysql服務器起用 performance_schema

my.cnf文件中
[mysqld]
performance_schema=ON

mysql> SHOW VARIABLES LIKE 'performance_schema';
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| performance_schema | ON    |
+--------------------+-------+
1 row in set (0.11 sec)

 

Performance Schema Instrument命名規則

最上層的instrument    組件

• idle
• stage
• statement
• wait

 

idle instrument      組件

idle event描述來自：socket_instances.STATE 列： Section 22.9.3.5, 「The socket_instances Table」.

stage instrument     組件

組成形式： stage/code_area/stage_name ， code_area 通常是sql or myisam。
stage name 通常來自： SHOW PROCESSLIST，如：Sorting result ，Sending data

Statement instrument 組件

statement/abstract/* ： 通常都是早期的stage，在抽象sql都還沒來得及解析的時候。
statement/com: SQL 命令操做 如：statement/com/Connect
statement/sql： SQL語句操做 如：statement/sql/create_db

Wait Instrument      組件

wait/io       ： IO 等待事件
wait/io/file  ： 文件IO等待事件。等待文件操做完成的時間如：fwrite().可是物理IO有可能由於緩存的緣由調用fwrite時不會寫磁盤。
wait/io/socket： socket相關的IO等待
wait/io/table ： 表相關的IO等待。通常對於記錄rows來講有fetch，insert，update，delete四種操做。
                 不像其餘等待事件，table I/O 還包含了其餘的等待事件。
                 好比：table io可能包含了文件IO和內存IO。由於讀取table rows的時候，有可能會去從文件讀取數據。

* wait/lock:
    * wait/lock/table   ： 表操做的鎖等待事件
* wait/synch:
    * wait/synch/cond   ：condition就是線程與線程之間的信號。
    * wait/synch/mutex  ： mutex主要用來鎖住一塊共享資源。
    * wait/synch/rwlock ： 讀寫鎖

 

收集全部的事件:

instrument 和 consumer 都會被enable ， 因此一開始他們不會收集全部的事件。
爲了讓他們都enable 或者 enable event timing。

執行如下兩條語句:
mysql> UPDATE setup_instruments SET ENABLED = 'YES', TIMED = 'YES';
Query OK, 338 rows affected (0.12 sec)

mysql> UPDATE setup_consumers SET ENABLED = 'YES';
Query OK, 8 rows affected (0.00 sec)

events_waits_history & events_waits_history_long 記錄了每一個thread最近10條和10000條event。

SELECT EVENT_ID, EVENT_NAME, TIMER_WAIT FROM events_waits_history WHERE THREAD_ID =21 ORDER BY EVENT_ID;

summary 表提供了整個時間段的一些統計信息。他們統計事件的處理方式和以前都不同。
若是想知道某個instrument 被執行的最頻繁，或者發生的頻率很是高，
能夠經過排序 events_waits_summary_global_by_event_name表，根據 COUNT_STAR 或者 SUM_TIMER_WAIT列。



mysql> SELECT EVENT_NAME, COUNT_STAR FROM events_waits_summary_global_by_event_name ORDER BY COUNT_STAR DESC LIMIT 10;
+--------------------------------------+------------+
| EVENT_NAME                           | COUNT_STAR |
+--------------------------------------+------------+
| wait/io/file/sql/FRM                 |       1682 |
| wait/io/file/innodb/innodb_data_file |        596 |
| idle                                 |        204 |
| wait/io/file/sql/binlog              |        170 |
| wait/io/file/myisam/kfile            |        110 |
| wait/io/file/myisam/dfile            |         90 |
| wait/io/file/sql/binlog_index        |         47 |
| wait/io/file/innodb/innodb_log_file  |         18 |
| wait/io/file/sql/dbopt               |         14 |
| wait/io/file/sql/casetest            |         10 |
+--------------------------------------+------------+
10 rows in set (0.31 sec)

mysql> SELECT EVENT_NAME, SUM_TIMER_WAIT FROM events_waits_summary_global_by_event_name ORDER BY SUM_TIMER_WAIT DESC LIMIT 10;
+--------------------------------------+-------------------+
| EVENT_NAME                           | SUM_TIMER_WAIT    |
+--------------------------------------+-------------------+
| idle                                 | 20173041031000000 |
| wait/io/file/innodb/innodb_data_file |      666638377892 |
| wait/io/file/sql/dbopt               |      177140672226 |
| wait/io/file/sql/FRM                 |       91152018924 |
| wait/io/file/sql/binlog              |       43352476474 |
| wait/io/file/innodb/innodb_log_file  |       35962857780 |
| wait/io/file/sql/binlog_index        |       20679496964 |
| wait/io/file/myisam/kfile            |       16840088732 |
| wait/io/file/sql/ERRMSG              |        8064330196 |
| wait/io/file/myisam/dfile            |        4785274304 |
+--------------------------------------+-------------------+
10 rows in set (0.03 sec)

setup表用來配置和顯示監控信息的。 例如：什麼樣的timer 被使用，
請查詢setup_timers

mysql> SELECT * FROM setup_timers;
+-----------+-------------+
| NAME      | TIMER_NAME  |
+-----------+-------------+
| idle      | MICROSECOND |
| wait      | CYCLE       |
| stage     | NANOSECOND  |
| statement | NANOSECOND  |
+-----------+-------------+
4 rows in set (0.00 sec)

setup_instruments 列出了哪些event會被收集與監控：

mysql> SELECT * FROM setup_instruments limit 10;
+-------------------------------------------------------+---------+-------+
| NAME                                                  | ENABLED | TIMED |
+-------------------------------------------------------+---------+-------+
| wait/synch/mutex/sql/PAGE::lock                       | YES     | YES   |
| wait/synch/mutex/sql/TC_LOG_MMAP::LOCK_sync           | YES     | YES   |
| wait/synch/mutex/sql/TC_LOG_MMAP::LOCK_active         | YES     | YES   |
| wait/synch/mutex/sql/TC_LOG_MMAP::LOCK_pool           | YES     | YES   |
| wait/synch/mutex/sql/LOCK_des_key_file                | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_commit       | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_commit_queue | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_done         | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_flush_queue  | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_index        | YES     | YES   |
+-------------------------------------------------------+---------+-------+
10 rows in set (0.00 sec)

哪些event是否是instrument，能夠給enabled設置yes or no

mysql>  UPDATE setup_instruments SET ENABLED = 'NO' WHERE NAME = 'wait/synch/mutex/sql/LOCK_mysql_create_db';
Query OK, 0 rows affected (0.01 sec)
Rows matched: 0  Changed: 0  Warnings: 0

 

消費者:接收EVENTS 的表

performance schema 使用收集的events 來更新performance_schema 數據庫的那些表，這些表扮演着事件信息消費者的角色。
setup_consumers 列出了可用的消費者 以及哪些是enabled.

mysql>  SELECT * FROM setup_consumers;
+--------------------------------+---------+
| NAME                           | ENABLED |
+--------------------------------+---------+
| events_stages_current          | YES     |
| events_stages_history          | YES     |
| events_stages_history_long     | YES     |
| events_statements_current      | YES     |
| events_statements_history      | YES     |
| events_statements_history_long | YES     |
| events_waits_current           | YES     |
| events_waits_history           | YES     |
| events_waits_history_long      | YES     |
| global_instrumentation         | YES     |
| thread_instrumentation         | YES     |
| statements_digest              | YES     |

 

 

http://www.javacoder.cn/?p=332

MySQL在5.6版本中包含了一個強大的特性——performance-schema

合理的使用這個數據庫中的表，能爲咱們解決一些瓶頸問題提供幫助，可是在我使用的5.6.21版本中，已經包含了52張表，後續還有可能會持續增長，因此搞清楚各個表之間的關係很重要。

mysql> show tables like '%setup%';
+----------------------------------------+
| Tables_in_performance_schema (%setup%) |
+----------------------------------------+
| setup_actors                           |
| setup_consumers                        |
| setup_instruments                      |
| setup_objects                          |
| setup_timers                           |
+----------------------------------------+
5 rows in set (0.01 sec)

 

1)setup_instruments [測量儀器]
使用performance-schema診斷問題的過程相似於醫生給病人看病的過程。"setup_instruments"猶如醫生可以使用的測量儀器（好比溫度計，CT，X光等），在MySQL的官方文檔中，使用「instrument」一詞來表示，這應該也是這個表的名稱的來源。這個表的每一行表明一個"instrument","instrument"在MySQL的源碼中表示爲一段爲了測量相應指標的代碼。這張表的三個字段分別爲「name enabled timed」,enabled表示是否啓用該"instrument", "timed"表示是否對其進行定量的耗時分析。

mysql> SELECT * FROM setup_instruments limit 10;
+-------------------------------------------------------+---------+-------+
| NAME                                                  | ENABLED | TIMED |
+-------------------------------------------------------+---------+-------+
| wait/synch/mutex/sql/PAGE::lock                       | YES     | YES   |
| wait/synch/mutex/sql/TC_LOG_MMAP::LOCK_sync           | YES     | YES   |
| wait/synch/mutex/sql/TC_LOG_MMAP::LOCK_active         | YES     | YES   |
| wait/synch/mutex/sql/TC_LOG_MMAP::LOCK_pool           | YES     | YES   |
| wait/synch/mutex/sql/LOCK_des_key_file                | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_commit       | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_commit_queue | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_done         | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_flush_queue  | YES     | YES   |
| wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_index        | YES     | YES   |
+-------------------------------------------------------+---------+-------+
10 rows in set (0.01 sec)

 

2）setup_objects
setup_objects相似某類病人(精神病，男科，婦科等)，在MySQL中指table, 表示哪些表須要「instrument」,該表的默認值爲：


mysql> SELECT * FROM setup_objects limit 10;                 
+-------------+--------------------+-------------+---------+-------+
| OBJECT_TYPE | OBJECT_SCHEMA      | OBJECT_NAME | ENABLED | TIMED |
+-------------+--------------------+-------------+---------+-------+
| TABLE       | mysql              | %           | NO      | NO    |
| TABLE       | performance_schema | %           | NO      | NO    |
| TABLE       | information_schema | %           | NO      | NO    |
| TABLE       | %                  | %           | YES     | YES   |
+-------------+--------------------+-------------+---------+-------+
4 rows in set (0.00 sec)

表示出了系統表「mysql performance_schema information_schema」外，都須要對其進行「instrument」操做。

 

3）threads
"threads「相似於某個病人，在MySQL中的某個線程，這個表有一個很是重要的字段」INSTRUMENTED「，表示是否須要對該線程進行」instrument「,這個字段由」setup_actors「表中的內容決定。setup_actors的默認內容以下


mysql> SELECT THREAD_ID,NAME,TYPE,INSTRUMENTED,role FROM threads limit 10;
+-----------+---------------------------------+------------+--------------+------+
| THREAD_ID | NAME                            | TYPE       | INSTRUMENTED | role |
+-----------+---------------------------------+------------+--------------+------+
|         1 | thread/sql/main                 | BACKGROUND | YES          | NULL |
|         2 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
|         3 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
|         4 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
|         5 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
|         6 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
|         7 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
|         8 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
|        11 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
|         9 | thread/innodb/io_handler_thread | BACKGROUND | YES          | NULL |
+-----------+---------------------------------+------------+--------------+------+
10 rows in set (0.01 sec)

 

線程分前臺線程和後臺線程，後臺線程指MySQL爲了完成任務二本身開啓的線程，這樣的線程的setup_objects.INSTRUMENTED字段默認爲true。

前臺線程值用戶操做而開啓的線程。這時若是當前用戶匹配setup_actors中的某個記錄，那麼setup_objects.INSTRUMENTED=true.
threads表的另外一個功能是能夠代替"show processlist"指令和"information_schema.processlist"表的功能，其不用獲取同步的mutex對象，不會又那麼重的額外消耗(overhead).

 

 

4)setup_consumers
setup_consumers表相似於各類診斷報告是否須要記錄的配置，這個表的默認配置爲：select * from setup_consumers;


mysql> select * from setup_consumers;
+--------------------------------+---------+
| NAME                           | ENABLED |
+--------------------------------+---------+
| events_stages_current          | YES     |
| events_stages_history          | YES     |
| events_stages_history_long     | YES     |
| events_statements_current      | YES     |
| events_statements_history      | YES     |
| events_statements_history_long | YES     |
| events_waits_current           | YES     |
| events_waits_history           | YES     |
| events_waits_history_long      | YES     |
| global_instrumentation         | YES     |
| thread_instrumentation         | YES     |
| statements_digest              | YES     |
+--------------------------------+---------+
12 rows in set (0.00 sec)

 5）setup_actors

mysql> select * from setup_actors  ;
+------+------+------+
| HOST | USER | ROLE |
+------+------+------+
| %    | %    | %    |
+------+------+------+
1 row in set (0.16 sec)

6)setup_timers

mysql> select * from  setup_timers ;
+-----------+-------------+
| NAME      | TIMER_NAME  |
+-----------+-------------+
| idle      | MICROSECOND |
| wait      | CYCLE       |
| stage     | NANOSECOND  |
| statement | NANOSECOND  |
+-----------+-------------+
4 rows in set (0.00 sec)

 

這個表的各個記錄還存在層級關係，只有當上級的配置啓用時纔會考慮下級的配置。
層級關係爲：
global_instrumentation
|----thread_instrumentation
|         |----events_waits_current
|         |           |-events_waits_history
|         |           |-events_waits_history_long
|         |----events_stages_current
|         |           |-events_stages_history
|         |           |-events_stages_history_long
|         |----events_statements_current
|                     |-events_statements_history
|                     |-events_statements_history_long
|-----statements_digest

當global_instrumentation啓用時，"thread_instrumentation"和"statements_digest"的配置纔有可能生效。其餘的配置類推。
只有當"setup_instruments"，"setup_objects",」setup_consumers「和"threads"都某一項測量指標都啓用時才能收集到它的信息。

結束語

對於」statement, stages, waits「這三類統計信息，除了setup_consumers中配置的名稱，還有summary版本的統計信息（summary_by_host_by_event_name, summary_by_user_event_name, summary_global_by_event_name）等按照各個維度的統計信息，外加file_instance, mutext_instance, rwlock_instance, table_io_waits_summary_by_index_usage, table_io_waits_summary_by_table,table_lock_waits_summary_by_table,外加一些雜項信息。
因爲這些都是基礎信息，網上有一個叫作ps_helper的項目，它提供了一些視圖，存儲過程來簡化performence_schema數據庫的使用，

MySQL官方的GUI工具——MySQL Workbench就含義ps_helper的安裝嚮導入下圖，

 

安裝完後會新增一個名爲"sys"的數據庫，裏面會包含一些視圖和存儲過程，具體的內容能夠查看官方文檔。

一些不錯的資料：
ps_helper官方 
MySQL Performance_Schema官網
Using-MySQL-5.6-Performance-Schema-To-Troubleshoot-Typical-Workload-Bottlenecks.pdf