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[20190423]简单测试latch nowilling等待模式.txt

原创 Oracle 作者:lfree 时间:2019-04-24 09:55:14 0 删除 编辑

[20190423]简单测试latch nowilling等待模式.txt


--//我对这个问题的理解就是如果参数willing=0,表示无法获取该latch,直接退出,再寻找类似的latch。

--//我仅仅知道redo copy latch具有这个特性:

> select addr,name,level#,latch#,gets,misses,sleeps,immediate_gets,immediate_misses,waiters_woken,waits_holding_latch,spin_gets,wait_time from v$latch_children where lower(name) like '%'||lower('redo copy')||'%' ;

ADDR             NAME       LEVEL#     LATCH#       GETS     MISSES     SLEEPS IMMEDIATE_GETS IMMEDIATE_MISSES WAITERS_WOKEN WAITS_HOLDING_LATCH  SPIN_GETS  WAIT_TIME

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

00000012D720ADA8 redo copy       4        208         53          0          0      500627938           304381             0                   0          0          0

00000012D720ACD0 redo copy       4        208         53          0          0      497827706           323330             0                   0          0          0

..

00000012D72086D8 redo copy       4        208         53          0          0      491448415           365472             0                   0          0          0

00000012D7208600 redo copy       4        208         53          0          0      508008338           391955             0                   0          0          0

48 rows selected.

--//你可以发现nowait latch 的一个特点,就是IMMEDIATE_GETS会相对很高.注我查询的生产系统的情况.测试环境不会这么高的.


http://andreynikolaev.wordpress.com/2010/04/12/latch-internals-information-sources/


--//参数如下,另外我前面blog写错了,where是最后1个参数。

kslgetl(laddr, wait, why, where) – Get exclusive latch 


More precisely, to request the latch Oracle kernel needs:

--//更准确地说,要请求闩锁Oracle内核需要:


laddress -- address of latch in SGA

wait     -- flag. If true, this is latch get in willing-to-wait mode..

why      -- context why the latch is acquired at this where.

where    -- code for location from where the latch is acquired.


1.环境:

SYS@book> @ ver1

PORT_STRING                    VERSION        BANNER

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

x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production


--//参考链接如下:http://blog.itpub.net/267265/viewspace-2641548/=>[20190416]exclusive latch测试脚本.txt


$ cat peek.sh

#! /bib/bash

# 参数如下:latch_name Monitoring_duration or laddr

sqlplus -s -l / as sysdba <<EOF

col laddr new_value laddr

SELECT sysdate,addr laddr FROM v\$latch_parent WHERE NAME='$1';

oradebug setmypid

$(seq $2|xargs -I{} echo -e 'oradebug peek 0x&laddr 8\nhost sleep 1' )

EOF


$ cat exclusive_latch.txt

/* 参数如下: @ exclusive_latch.txt latch_name willing why where sleep_num */

--//connect / as sysdba

col laddr new_value laddr

SELECT addr laddr FROM v$latch_parent WHERE NAME='&&1';

oradebug setmypid

oradebug call kslgetl 0x&laddr &&2 &&3 &&4

host sleep &&5

oradebug call kslfre 0x&laddr

--//exit


$ cat y1.sh

#! /bin/bash

zdate=$(date '+%Y%m%d%H%M%S')

echo $zdate

source peek.sh 'test excl. parent2 l0' 20 | timestamp.pl >| /tmp/peekx_${zdate}.txt &

seq 20 | xargs -I{} echo -e 'sqlplus -s -l / as sysdba <<< @latch_free\nsleep 1'  | bash >| /tmp/latch_freeo_${zdate}.txt &

# 参数如下: @ exclusive_latch.txt latch_name willing why where sleep_num

sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 1 2 6" > /dev/null &

sleep 2

sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 3 4 6" > /dev/null &

sleep 4.1

sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 5 6 6" > /dev/null &

wait


$ . y1.sh

20190424091250

[3]-  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 1 2 6" > /dev/null

[1]   Done                    source peek.sh 'test excl. parent2 l0' 20 | timestamp.pl >|/tmp/peekx_${zdate}.txt

[4]-  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 3 4 6" > /dev/null

[5]+  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 5 6 6" > /dev/null

[2]+  Done                    seq 20 | xargs -I{} echo -e 'sqlplus -s -l / as sysdba <<< @latch_free\nsleep 1' | bash >|/tmp/latch_freeo_${zdate}.txt


2.测试:

$ grep  -v '^.*: $' /tmp/peekx_20190424091250.txt | cut -c10- | uniq -c

      1  SYSDATE             LADDR

      1  ------------------- ----------------

      1  2019-04-24 09:12:50 0000000060009978

      1  Statement processed.

      6  [060009978, 060009980) = 00000015 00000000

      1  [060009978, 060009980) = 00000000 00000000

      6  [060009978, 060009980) = 00000015 00000000

      7  [060009978, 060009980) = 00000000 00000000

--//你可以发现第1个会话申请成功,第2个会话没有申请成功,直接退出.第3个会话申请成功(因为sleep 2+4.1秒).


--//cat /tmp/latch_freeo_20190424091250.txt

2019-04-24 09:12:50

2019-04-24 09:12:51

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=2 why=1, SID=295


2019-04-24 09:12:52

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=2 why=1, SID=295


2019-04-24 09:12:53

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=2 why=1, SID=295


2019-04-24 09:12:54

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=2 why=1, SID=295


2019-04-24 09:12:55

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=2 why=1, SID=295


2019-04-24 09:12:56

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=6 why=5, SID=295


2019-04-24 09:12:57

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=6 why=5, SID=295


2019-04-24 09:12:58

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=6 why=5, SID=295


2019-04-24 09:13:00

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=6 why=5, SID=295


2019-04-24 09:13:01

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=6 why=5, SID=295


2019-04-24 09:13:02

Process 21

 holding: 0000000060009978  "test excl. parent2 l0" lvl=0 whr=6 why=5, SID=295


2019-04-24 09:13:03

2019-04-24 09:13:04

--//21=0x15,与peek看到的一致.


3.手工测试看看函数的返回值

--//session 1:

SYS@book> @ exclusive_latch.txt 'test excl. parent2 l0' 0 1 2 60

old   1: SELECT addr laddr FROM v$latch_parent WHERE NAME='&&1'

new   1: SELECT addr laddr FROM v$latch_parent WHERE NAME='test excl. parent2 l0'


LADDR

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

0000000060009978


Statement processed.

Function returned 1

Function returned 0


--//session 2:

SYS@book> @ exclusive_latch.txt 'test excl. parent2 l0' 0 3 4 6

old   1: SELECT addr laddr FROM v$latch_parent WHERE NAME='&&1'

new   1: SELECT addr laddr FROM v$latch_parent WHERE NAME='test excl. parent2 l0'


LADDR

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

0000000060009978


Statement processed.

Function returned 0


ORA-00600: internal error code, arguments: [510], [0x060009978], [test excl. parent2 l0], [], [], [], [], [], [], [], [], []


--//可以发现申请成功函数返回值是1.失败是0.只所以session 2报错主要原因是没有申请成功,kslfre肯定报错.


4.看看latch统计信息的情况:

SYS@book> select addr,name,level#,latch#,gets,misses,sleeps,immediate_gets,immediate_misses,waiters_woken,waits_holding_latch,spin_gets,wait_time from v$latch_parent   where lower(name) like '%'||lower('test excl. parent2 l0')||'%';

ADDR             NAME                  LEVEL#     LATCH#       GETS     MISSES     SLEEPS IMMEDIATE_GETS IMMEDIATE_MISSES WAITERS_WOKEN WAITS_HOLDING_LATCH  SPIN_GETS  WAIT_TIME

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

0000000060009978 test excl. parent2 l0      0          5          4          0          0              4                3             0                   0          0          0


--//重复测试:

$ . y1.sh

20190424094217

[3]-  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 1 2 6" > /dev/null

[1]   Done                    source peek.sh 'test excl. parent2 l0' 20 | timestamp.pl >|/tmp/peekx_${zdate}.txt

[4]-  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 3 4 6" > /dev/null

[5]+  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 5 6 6" > /dev/null

[2]+  Done                    seq 20 | xargs -I{} echo -e 'sqlplus -s -l / as sysdba <<< @latch_free\nsleep 1' | bash >|/tmp/latch_freeo_${zdate}.txt


SYS@book> select addr,name,level#,latch#,gets,misses,sleeps,immediate_gets,immediate_misses,waiters_woken,waits_holding_latch,spin_gets,wait_time from v$latch_parent   where lower(name) like '%'||lower('test excl. parent2 l0')||'%';

ADDR             NAME                  LEVEL#     LATCH#       GETS     MISSES     SLEEPS IMMEDIATE_GETS IMMEDIATE_MISSES WAITERS_WOKEN WAITS_HOLDING_LATCH  SPIN_GETS  WAIT_TIME

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

0000000060009978 test excl. parent2 l0      0          5          4          0          0              6                4             0                   0          0          0


--//可以发现IMMEDIATE_GETS增加2次,IMMEDIATE_MISSES增加1次.


$ . y1.sh

20190424094448

[3]-  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 1 1 2 6" > /dev/null

--//注意我修改为willing=1方式获取.

[1]   Done                    source peek.sh 'test excl. parent2 l0' 20 | timestamp.pl >|/tmp/peekx_${zdate}.txt

[4]-  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 3 4 6" > /dev/null

[5]+  Done                    sqlplus / as sysdba <<< "@ exclusive_latch.txt 'test excl. parent2 l0' 0 5 6 6" > /dev/null

[2]+  Done                    seq 20 | xargs -I{} echo -e 'sqlplus -s -l / as sysdba <<< @latch_free\nsleep 1' | bash >|/tmp/latch_freeo_${zdate}.txt


SYS@book> select addr,name,level#,latch#,gets,misses,sleeps,immediate_gets,immediate_misses,waiters_woken,waits_holding_latch,spin_gets,wait_time from v$latch_parent   where lower(name) like '%'||lower('test excl. parent2 l0')||'%';

ADDR             NAME                  LEVEL#     LATCH#       GETS     MISSES     SLEEPS IMMEDIATE_GETS IMMEDIATE_MISSES WAITERS_WOKEN WAITS_HOLDING_LATCH  SPIN_GETS  WAIT_TIME

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

0000000060009978 test excl. parent2 l0      0          5          5          0          0              7                5             0                   0          0          0


--//可以发现gets增加1,IMMEDIATE_GETS增加1次,IMMEDIATE_MISSES增加1次.

--//我希望这个这个帖子对于理解latch的统计有所帮助.以前我对于这些统计参数的理解一片混乱.

--//大家可以适当调整sleep参数,测试看看各种情况.


来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/267265/viewspace-2642329/,如需转载,请注明出处,否则将追究法律责任。

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