[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.

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