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DB buffer bussy wait 分析一例

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标签:redo   3.1   data   3.5   style   exec   str   padding   border   

 

 

 

DB层分析OI

DB层分析OI的信息如下:

 

1. 异常时间段,  Logical reads:/ Physical reads/ Physical write  指标都低于正常时间段。说明数据库本身消耗i/o 并不高。但是nmon显示disk 读写非常高,

 

同时现场分析, I/O 资源消耗最大可达40M-70M/s,任务可以顺利完成。同时注意到

通过topas 来看,在一些时候,hdisk 在 tps和kbps 为0的情况下,磁盘繁忙程度达到99%,所以建议如下:

是这个现在已有的信息能够看到的一些问题,还需要OS层面给一些东西,需要OS介入帮助看看底层是否有什么问题。请主机组检查存储

 

 

 

2. 等待事件buffer busy waits  占首位,消耗了很多资源,主要是sql  2mwvn9xwq1tz3 消耗。建议检查sql

 

检查这个sql 执行计划2mwvn9xwq1tz3

 

 

Elapsed Time (s)

Executions

Elapsed Time per Exec (s)

%Total

%CPU

%IO

SQL Id

SQL Module

SQL Text

80,962.92

24,804

3.26

33.97

0.00

0.00

2mwvn9xwq1tz3

e:IEU:cp:IEU_WL_CS

select (RUNNING_PROCESSES-MAX_...

 

                                                   分析sql 结果:

 

 

Sql 执行计划没有变化。主要消耗在buffer busy wait ,说明当时缓存区争用,怀疑跟系统I/O 处理不过来,导致缓存存在问题。

 

SQL_ID 2mwvn9xwq1tz3

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

select (RUNNING_PROCESSES-MAX_PROCESSES) ,MAX_PROCESSES 

,NVL(SLEEP_SECONDS,0) ,DIAGNOSTIC_LEVEL into :b0,:b1,:b2,:b3:b4  from 

FND_CONCURRENT_QUEUES where ((DBLICATION_ID=:b5 and 

CONCURRENT_QUEUE_ID=:b6) and (TARGET_NODE=:b7 or (TARGET_NODE is null  

and :b7 is null )))

 

Plan hash value: 356935968

 

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

| Id  | Operation                   | Name                     | Rows  | Bytes | Cost (%CPU)| Time     |

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

|   0 | SELECT STATEMENT            |                          |       |       |     1 (100)|          |

|   1 |  TABLE ACCESS BY INDEX ROWID| FND_CONCURRENT_QUEUES    |     1 |    22 |     1   (0)| 00:00:01 |

|   2 |   INDEX UNIQUE SCAN         | FND_CONCURRENT_QUEUES_U1 |     1 |       |     0   (0)|          |

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

 

 

详细分析如下:

-》 1 。正常时间段:等待事件正常, Logical reads:/ Physical reads/ Physical write  指标都高于 异常时间段。

 

 


Snap Id

Snap Time

Sessions

Cursors/Session

Begin Snap:

36769

12-6月 -17 20:00:52

216

10.5

End Snap:

36773

13-6月 -17 00:00:22

229

9.3

Elapsed:

 

239.51 (mins)

 

 

DB Time:

 

1,570.72 (mins)

 

 

 

Top 5 Timed Foreground Events

Event

Waits

Time(s)

Avg wait (ms)

% DB time

Wait Class

db file sequential read

5,750,530

23,950

4

25.41

User I/O

log buffer space

72,789

15,988

220

16.96

Configuration

DB CPU

 

10,941

 

11.61

 

SQL*Net message from dblink

61,789

7,296

118

7.74

Network

direct path read

385,065

6,336

16

6.72

User I/O

 

Segments by Buffer Busy Waits

% of Capture shows % of Buffer Busy Waits for each top segment compared

with total Buffer Busy Waits for all segments captured by the Snapshot

Owner

Tablespace Name

Object Name

Subobject Name

Obj. Type

Buffer Busy Waits

% of Capture

MSC

DBS_TS_INTERFACE

MSC_ST_SYSTEM_ITEMS

SYSTEM_ITEMS_3021

TABLE PARTITION

13,842

45.12

DATALOAD

TS_DATA_LOAD

ZTE_ERP_WIP_DETAIL

 

TABLE

6,058

19.75

DBLSYS

DBS_TS_TX_DATA

FND_CONCURRENT_QUEUES

 

TABLE

5,119

16.69

 

 

Load Profile

 

Per Second

Per Transaction

Per Exec

Per Call

DB Time(s):

6.6

0.5

0.00

0.11

DB CPU(s):

0.8

0.1

0.00

0.01

Redo size:

6,145,675.1

497,949.9

 

 

Logical reads:

223,510.5

18,109.8

 

 

Block changes:

20,265.5

1,642.0

 

 

Physical reads:

2,507.0

203.1

 

 

Physical writes:

3,069.3

248.7

 

 

User calls:

60.5

4.9

 

 

Parses:

3.3

0.3

 

 

Hard parses:

0.9

0.1

 

 

W/A MB processed:

3.7

0.3

 

 

Logons:

0.2

0.0

 

 

Executes:

2,988.9

242.2

 

 

Rollbacks:

0.3

0.0

 

 

Transactions:

12.3

 

 

 

 

 

 

-》 2 .异常时间段。等待事件buffer busy waits  占首位,消耗了很多资源,主要是sql  2mwvn9xwq1tz3 消耗。

       Logical reads:/ Physical reads/ Physical write  指标都低于正常时间段。说明数据库本身消耗i/o 并不高。,

 


Snap Id

Snap Time

Sessions

Cursors/Session

Begin Snap:

36817

14-Jun-17 20:00:02

228

12.8

End Snap:

36821

15-Jun-17 00:00:21

235

10.9

Elapsed:

 

240.31 (mins)

 

 

DB Time:

 

6,207.36 (mins)

 

 

 

 

Buffer Cache:

29,184M

29,184M

Std Block Size:

8K

Shared Pool Size:

10,240M

10,240M

Log Buffer:

72,708K

 

Event

Waits

Time(s)

Avg wait (ms)

% DB time

Wait Class

buffer busy waits

78,775

207,914

2639

55.82

Concurrency

 

Segments by Buffer Busy Waits

  • % of Capture shows % of Buffer Busy Waits for each top segment compared
  • with total Buffer Busy Waits for all segments captured by the Snapshot

Owner

Tablespace Name

Object Name

Subobject Name

Obj. Type

Buffer Busy Waits

% of Capture

DBLSYS

DBS_TS_TX_DATA

FND_CONCURRENT_QUEUES

 

TABLE

90,802

72.49

 

 

2mwvn9xwq1tz3

select (RUNNING_PROCESSES-MAX_PROCESSES) , MAX_PROCESSES , NVL(SLEEP_SECONDS, 0) , DIAGNOSTIC_LEVEL into :b0, :b1, :b2, :b3:b4 from FND_CONCURRENT_QUEUES where ((DBLICATION_ID=:b5 and CONCURRENT_QUEUE_ID=:b6) and (TARGET_NODE=:b7 or (TARGET_NODE is null and :b7 is null )))

 

Load Profile

 

Per Second

Per Transaction

Per Exec

Per Call

DB Time(s):

20.0

1.7

0.06

0.15

DB CPU(s):

0.2

0.0

0.00

0.00

Redo size:

1,836,990.9

154,577.6

 

 

Logical reads:

35,973.5

3,027.1

 

 

Block changes:

5,531.3

465.4

 

 

Physical reads:

343.4

28.9

 

 

Physical writes:

550.6

46.3

 

 

User calls:

132.6

11.2

 

 

Parses:

3.0

0.3

 

 

Hard parses:

0.8

0.1

 

 

W/A MB processed:

2.6

0.2

 

 

Logons:

0.1

0.0

 

 

Executes:

332.7

28.0

 

 

Rollbacks:

0.5

0.0

 

 

Transactions:

11.9

 

 

 

 

 

è  3. 检查这个sql 执行计划2mwvn9xwq1tz3

 

6.11没问题:

 

 

 

6.14有问题:

 

 

 

 

 

DB buffer bussy wait 分析一例

标签:redo   3.1   data   3.5   style   exec   str   padding   border   

原文地址:http://www.cnblogs.com/feiyun8616/p/7041000.html

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