码迷,mamicode.com
首页 > 数据库 > 详细

InnoDB信息说明

时间:2018-08-14 11:12:16      阅读:209      评论:0      收藏:0      [点我收藏+]

标签:作者   memory   读取   output   operation   ast   库存   oop   database   

InnoDB是MySQL数据库发展至今一款至关重要的数据库存储引擎,其不仅支持事务特性,并且具有丰富的统计信息,便于数据库管理人员了解最近InnoDB存储引擎的运行状态。

 

早期版本的InnoDB存储引擎通过在内部新建一张名为innodb_monitor的表进行实现,InnoDB内部检测到该表后,会定时输出InnoDB引擎相关统计信息。而现在的InnoDB存储引擎通过命令show engine innodb status实现对InnoDB存储引擎统计信息的查看,在MySQL客户端执行show engine innodb status\G,获取到的结果可能如下:

 

=====================================

 

140708 21:35:01 INNODB MONITOR OUTPUT

 

=====================================

 

Per second averages calculated from the last 54 seconds

 

-----------------

 

BACKGROUND THREAD

 

-----------------

 

srv_master_thread loops: 129 1_second, 128 sleeps, 8 10_second, 76 background, 76 flush

 

srv_master_thread log flush and writes: 129

 

----------

 

SEMAPHORES

 

----------

 

OS WAIT ARRAY INFO: reservation count 53606, signal count 55906

 

Mutex spin waits 525951, rounds 2435436, OS waits 40130

 

RW-shared spins 36905, rounds 444653, OS waits 9660

 

RW-excl spins 5298, rounds 156489, OS waits 2307

 

Spin rounds per wait: 4.63 mutex, 12.05 RW-shared, 29.54 RW-excl

 

------------

 

TRANSACTIONS

 

------------

 

Trx id counter 19FFF

 

Purge done for trx‘s n:o < 13696 undo n:o < 0

 

History list length 15274

 

LIST OF TRANSACTIONS FOR EACH SESSION:

 

---TRANSACTION 19F65, not started

 

mysql tables in use 1, locked 0

 

MySQL thread id 52, OS thread handle 0x7f8bfd1b9700, query id 1040279 localhost root

 

SELECT c FROM sbtest1 WHERE id=199077

 

………………... any other TRANSACTIONS ……………………..

 

--------

 

FILE I/O

 

--------

 

I/O thread 0 state: waiting for completed aio requests (insert buffer thread)

 

I/O thread 1 state: waiting for completed aio requests (log thread)

 

I/O thread 2 state: waiting for completed aio requests (read thread)

 

………………. other three read threads …………….….

 

I/O thread 6 state: waiting for completed aio requests (write thread)

 

………………. other three write threads …………….….

 

Pending normal aio reads: 0 [0, 0, 0, 0] , aio writes: 0 [0, 0, 0, 0] ,

 

 ibuf aio reads: 0, log i/o‘s: 0, sync i/o‘s: 0

 

Pending flushes (fsync) log: 1; buffer pool: 0; flash cache 0

 

296 OS file reads, 47547 OS file writes, 40960 OS fsyncs

 

0.00 reads/s, 0 avg bytes/read, 755.62 writes/s, 750.19 fsyncs/s

 

-------------------------------------

 

INSERT BUFFER AND ADAPTIVE HASH INDEX

 

-------------------------------------

 

Ibuf: size 1, free list len 0, seg size 2, 0 merges

 

merged operations:

 

insert 0, delete mark 0, delete 0

 

discarded operations:

 

insert 0, delete mark 0, delete 0

 

Hash table size 21249841, node heap has 294 buffer(s)

 

17860.30 hash searches/s, 13956.39 non-hash searches/s

 

---

 

LOG

 

---

 

Log sequence number 184703155

 

Log flushed up to   184699426

 

Last checkpoint at  109334220

 

1 pending log writes, 0 pending chkp writes

 

40703 log i/o‘s done, 749.84 log i/o‘s/second

 

----------------------

 

BUFFER POOL AND MEMORY

 

----------------------

 

Total memory allocated 10994319360; in additional pool allocated 0

 

Dictionary memory allocated 43910

 

Buffer pool size   655359

 

Free buffers       646841

 

Database pages     8224

 

Old database pages 3015

 

Modified db pages  5270

 

Pending reads 0

 

Pending writes: LRU 0, flush list 0, single page 0

 

Pages made young 1, not young 0

 

0.00 youngs/s, 0.00 non-youngs/s

 

Pages read 149, created 8075, written 6557

 

0.00 reads/s, 38.13 creates/s, 5.52 writes/s

 

Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000

 

Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s

 

LRU len: 8224, unzip_LRU len: 0

 

I/O sum[0]:cur[0], unzip sum[0]:cur[0]

 

Async Flush: 0, Sync Flush: 0, LRU List Flush: 0, Flush List Flush: 6557

 

--------------

 

ROW OPERATIONS

 

--------------

 

0 queries inside InnoDB, 0 queries in queue

 

61 read views open inside InnoDB

 

Main thread process no. 30423, id 140238424880896, state: sleeping

 

Number of rows inserted 451965, updated 103933, deleted 51957, read 21009001

 

962.26 inserts/s, 1924.65 updates/s, 962.15 deletes/s, 381640.41 reads/s

 

----------------------------

 

END OF INNODB MONITOR OUTPUT

 

============================

二、        统计信息说明

 

根据上面的显示,可以把InnoDB存储引擎的统计信息分为:

 

1.           基础信息

 

2.           后台线程(background thread)

 

3.           信号量(semaphores)

 

4.           事务(transactions)

 

5.           I/O

 

6.           insert buffer & adaptive hash

 

7.           log

 

8.           buffer pool & memory

 

9.           row operations

 

下面结合上节中显示的信息分别对以上分类进行说明。

 

基础信息

 

Per second averages calculated from the last 54 seconds

 

InnoDB内部统计的信息都是一段时间内的平均值,默认情况下为60s一个时间间隔计算,上述显示的54s是执行show engine innodb status命令距上次统计结束为54s,下面显示的信息为54s内的平均值,一般认为,该值在比较大时才有意义,因为当该值比较小时,偶然的波动会造成统计信息变化很大,不能很好地反应InnoDB存储引擎内部实际情况。

 

background thread

 

-----------------

 

BACKGROUND THREAD

 

-----------------

 

srv_master_thread loops: 129 1_second, 128 sleeps, 8 10_second, 76 background, 76 flush

 

srv_master_thread log flush and writes: 129

 

MySQL内部后台有个线程负责数据的刷盘和undo的清理(不使用独立的purge线程)工作,后台线程是一个死循环,根据InnoDB存储引擎的繁忙程度执行数据刷盘操作,主要操作如下图:

 

 

 

从background thread信息中,可以看出1s的循环有129次,10s的循环有8次,128次sleep和76次进入background模式,进行了76次数据刷盘和129次日志刷盘,整个background thread信息显示,InnoDB内部处于相对空闲状态。

 

semaphores

 

----------

 

SEMAPHORES

 

----------

 

OS WAIT ARRAY INFO: reservation count 53606, signal count 55906

 

Mutex spin waits 525951, rounds 2435436, OS waits 40130

 

RW-shared spins 36905, rounds 444653, OS waits 9660

 

RW-excl spins 5298, rounds 156489, OS waits 2307

 

Spin rounds per wait: 4.63 mutex, 12.05 RW-shared, 29.54 RW-excl

 

信号量段显示了InnoDB存储引擎内部锁信息,在大并发量请求时,InnoDB不可避免存在资源竞争,这个时候,部分事务需要通过锁等待,等待相关事务释放资源后才能继续执行,上面显示的饿信息就是InnoDB内部锁等待信息。除了上面部分信息外,如果InnoDB存储引擎存在死锁状态,还会在以上信息下面增加相应的的死锁信息。

 

transactions

 

------------

 

TRANSACTIONS

 

------------

 

Trx id counter 19FFF

 

Purge done for trx‘s n:o < 13696 undo n:o < 0

 

History list length 15274

 

事务段信息显示当前InnoDB内部正在执行的事务,因为InnoDB存储引擎支持事务并发执行,所以InnoDB内部同时存在许多事务。

 

事务id在InnoDB内部是递增的,从当前事务信息看,下一个事务id为0x19FFF,而当前purge到的undo日志号no为13695,当前等待purge操作的事务有15274个,单从这些信息上就可以看出,当前InnoDB内部处于繁忙状态,等待pruge的事务数在不断增加。

 

上面一部分可以看做是事务的总结信息,而LIST OF TRANSACTIONS FOR EACH SESSION:后面显示的是当前InnoDB内部每个事务的具体状态:

 

---TRANSACTION 19F65, not started

 

mysql tables in use 1, locked 0

 

MySQL thread id 52, OS thread handle 0x7f8bfd1b9700, query id 1040279 localhost root

 

SELECT c FROM sbtest1 WHERE id=199077

 

上述显示了当前InnoDB内部1个事务的信息,not started说明该事务处于非活动状态,如果是活动状态则为active,mysql tables in use说明当前事务操作的表数,locked表示表被锁的个数(innodb内部支持行锁,所以一般表锁使用比较少,只有在如alter table等操作是才会锁表),mysql thread id为当前连接分配的id,os thread handle为连接线程的句柄,query id为当前查询的id,后面显示了具体的查询SQL。

I/O

 

--------

 

FILE I/O

 

--------

 

I/O thread 0 state: waiting for completed aio requests (insert buffer thread)

 

I/O thread 1 state: waiting for completed aio requests (log thread)

 

I/O thread 2 state: waiting for completed aio requests (read thread)

 

………………. other three read threads …………….….

 

I/O thread 6 state: waiting for completed aio requests (write thread)

 

………………. other three write threads …………….….

 

Pending normal aio reads: 0 [0, 0, 0, 0] , aio writes: 0 [0, 0, 0, 0] ,

 

 ibuf aio reads: 0, log i/o‘s: 0, sync i/o‘s: 0

 

Pending flushes (fsync) log: 1; buffer pool: 0; flash cache 0

 

296 OS file reads, 47547 OS file writes, 40960 OS fsyncs

 

reads/s, 0 avg bytes/read, 755.62 writes/s, 750.19 fsyncs/s

 

I/O段显示当前InnoDB引擎内部I/O使用情况,InnoDB内部采用异步I/O的模式进行数据的读写操作,默认情况下有1个insert buffer线程,1个日志线程,4个读数据线程和4个写数据线程。

 

线程信息后面部分为I/O统计信息,总共进行了296次读取,47547次写入,fsync为40960次,平均读数据为0,写输入为755.62次/s, fsyncs为750.19次/s,从以上信息分析,该InnoDB存储引擎内部事务基本上都是写入事务,I/O基本已经达到性能瓶颈。

 

insert buffer & adaptive hash

 

-------------------------------------

 

INSERT BUFFER AND ADAPTIVE HASH INDEX

 

-------------------------------------

 

Ibuf: size 1, free list len 0, seg size 2, 0 merges

 

merged operations:

 

insert 0, delete mark 0, delete 0

 

discarded operations:

 

insert 0, delete mark 0, delete 0

 

上面部分显示插入缓冲信息,从MySQL 5.5开始,insert buffer不止统计insert信息还包括delete和update信息,被称之为change buffer(delete mark为update的信息,InnoDB内部update通过把记录的delete flag设置成true实现)。

 

单从上面的信息来看,change buffer没有涉及到需要合并的insert/update/delete操作,insert buffer功能没能得到利用。

 

Hash table size 21249841, node heap has 294 buffer(s)

 

17860.30 hash searches/s, 13956.39 non-hash searches/s

 

InnoDB内部对已某张页查询达到一定数量后,内部会为该页采用哈希方式建立索引,InnoDB认为,当某张页在一段时间被频繁使用时,那么在后面被用到的概率也将非常高,所以为该页建立哈希索引能加速该页的查找。hash table size显示了内部自适应哈希表的大小,hash search和non-hash search分别显示了InnoDB内部查找时使用自适应哈希和普通索引查找每秒的次数,单从上述信息看来自适应哈希查找占到了55%左右,自适应哈希效果明显。

log

---

LOG

---

Log sequence number 184703155

Log flushed up to   184699426

Last checkpoint at  109334220

1 pending log writes, 0 pending chkp writes

40703 log i/o‘s done, 749.84 log i/o‘s/second

InnoDB log信息显示了当前内部重做日志(redo log)的写入情况,InnoDB内部通过LSN来实现redo log和事务的对应,log sequence number说明当前系统内部事务执行LSN为184703155,而log flushed up to表示redo log已经保存到磁盘的LSN为184699426,而last checkpoint at表示最近数据和redo log都保存到磁盘的LSN为109334220。

通过上面的信息可以得知:如果这个时候发生某种意外导致MySQL意外宕机,LSN > 184699426的事务可能会被丢失,而LSN在109334220和184699426中间的事务需要通过redo log恢复。LSN < 109334220的数据,因为已经保存到磁盘了,所以不会因为宕机而丢失。

buffer pool & memory

----------------------

BUFFER POOL AND MEMORY

----------------------

Total memory allocated 10994319360; in additional pool allocated 0

Dictionary memory allocated 43910

Buffer pool size   655359

Free buffers       646841

Database pages     8224

Old database pages 3015

Modified db pages  5270

Pending reads 0

Pending writes: LRU 0, flush list 0, single page 0

Pages made young 1, not young 0

0.00 youngs/s, 0.00 non-youngs/s

Pages read 149, created 8075, written 6557

0.00 reads/s, 38.13 creates/s, 5.52 writes/s

Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000

Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s

LRU len: 8224, unzip_LRU len: 0

I/O sum[0]:cur[0], unzip sum[0]:cur[0]

Async Flush: 0, Sync Flush: 0, LRU List Flush: 0, Flush List Flush: 6557

InnoDB内部采用buffer pool的形式缓存数据,对于InnoDB存储引擎来说,buffer pool越大,内存中缓存的数据也就越多,系统的性能就越好。上述信息显示,InnoDB占用内存大约10G,

buffer的大小大约为655359(单位16K,下同),而空闲大约为646841,被使用的页为8224 + 3015,其中脏页为8224, 3015为非脏页。

从上述信息显示,InnoDB内存过大,数据全部落在内存中。

Buffer pool hit rate 1000 / 1000内存命中率100%,等待flush的页为6557

row operations

--------------

ROW OPERATIONS

--------------

0 queries inside InnoDB, 0 queries in queue

61 read views open inside InnoDB

Main thread process no. 30423, id 140238424880896, state: sleeping

Number of rows inserted 451965, updated 103933, deleted 51957, read 21009001

962.26 inserts/s, 1924.65 updates/s, 962.15 deletes/s, 381640.41 reads/s

row operations显示了InnoDB存储引擎内部记录操作信息,打开了61个read views,后面显示了主线程信息和状态,最后显示了自启动以来,所有的insert/update/delete/read数量和每秒的平均值。

 

 
本文来自网易云社区,经作者蒋鸿翔授权发布。

InnoDB信息说明

标签:作者   memory   读取   output   operation   ast   库存   oop   database   

原文地址:https://www.cnblogs.com/163yun/p/9472494.html

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!