[20190409]latch get 引數where and why.txt

--//這一陣子一直在探究latch,mutex的問題,思路好亂.放假在看了許多連結.

--//被裡面的X$搞得有點暈.慢慢理解看看:

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

--//感覺作者這裡寫錯了,應該是kslgetl(laddr, wait, where, why).這樣才與下面的連結對上.

More precisely, to request the latch Oracle kernel needs:

--//更準確地說，要請求閂鎖Oracle核心需要：

laddress -- address of latch in SGA

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

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

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

--//我主要關注where,why如何取值.

1-latch address

2-immediate get (0 means yes, 1 means no)

3-where (X$KSLLW.INDX)

4-why (X$KSLWSC.INDX)

5-mode (8=shared,16=exclusive; only for ksl_get_shared_latch function)

--//以作者寫的例子看看latch='DMON Work Queues Latch'的情況:

1.環境:

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

SYS@book> select addr, name from v$latch where name='DMON Work Queues Latch';

ADDR NAME

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

000000006004C300 DMON Work Queues Latch

SYS@book> select addr, name from v$latch_parent where name='DMON Work Queues Latch';

ADDR NAME

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

000000006004C300 DMON Work Queues Latch

SYS@book> select addr, name from v$latch_children where name='DMON Work Queues Latch';

no rows selected

--//僅僅存在父拴鎖.

2.首先看看why的取值:

--//4-why (X$KSLWSC.INDX)

SYS@book> select * from x$kslwsc where ksllasnam ='DMON Work Queues Latch';

ADDR INDX INST_ID KSLNOWTF KSLSLEEP KSLWSCWSL KSLWSCLTHG KSLLASNAM

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

00000000861C08C0 4972 1 0 1 1 0 DMON Work Queues Latch

00000000861C08E0 4973 1 0 0 0 0 DMON Work Queues Latch

00000000861C0900 4974 1 0 0 0 0 DMON Work Queues Latch

00000000861C0920 4975 1 0 0 0 0 DMON Work Queues Latch

00000000861C0940 4976 1 0 0 0 0 DMON Work Queues Latch

00000000861C0960 4977 1 0 0 0 0 DMON Work Queues Latch

00000000861C0980 4978 1 0 0 0 0 DMON Work Queues Latch

00000000861C09A0 4979 1 0 0 0 0 DMON Work Queues Latch

00000000861C09C0 4980 1 0 0 0 0 DMON Work Queues Latch

00000000861C09E0 4981 1 0 0 0 0 DMON Work Queues Latch

00000000861C0A00 4982 1 0 0 0 0 DMON Work Queues Latch

00000000861C0A20 4983 1 0 0 0 0 DMON Work Queues Latch

00000000861C0A40 4984 1 0 0 0 0 DMON Work Queues Latch

00000000861C0A60 4985 1 0 0 0 0 DMON Work Queues Latch

00000000861C0A80 4986 1 0 0 0 0 DMON Work Queues Latch

00000000861C0AA0 4987 1 0 0 0 0 DMON Work Queues Latch

00000000861C0AC0 4988 1 0 0 0 0 DMON Work Queues Latch

00000000861C0AE0 4989 1 0 0 0 0 DMON Work Queues Latch

00000000861C0B00 4990 1 0 0 0 0 DMON Work Queues Latch

00000000861C0B20 4991 1 0 0 0 0 DMON Work Queues Latch

00000000861C0B40 4992 1 0 0 0 0 DMON Work Queues Latch

00000000861C0B60 4993 1 0 0 0 0 DMON Work Queues Latch

00000000861C0B80 4994 1 0 0 0 0 DMON Work Queues Latch

00000000861C0BA0 4995 1 0 0 0 0 DMON Work Queues Latch

00000000861C0BC0 4996 1 0 0 0 0 DMON Work Queues Latch

00000000861C0BE0 4997 1 0 0 0 0 DMON Work Queues Latch

00000000861C0C00 4998 1 0 0 0 0 DMON Work Queues Latch

00000000861C0C20 4999 1 0 0 0 0 DMON Work Queues Latch

00000000861C0C40 5000 1 0 0 0 0 DMON Work Queues Latch

00000000861C0C60 5001 1 0 0 0 0 DMON Work Queues Latch

00000000861C0C80 5002 1 0 0 0 0 DMON Work Queues Latch

00000000861C0CA0 5003 1 0 0 0 0 DMON Work Queues Latch

00000000861C0CC0 5004 1 0 0 0 0 DMON Work Queues Latch

00000000861C0CE0 5005 1 0 0 0 0 DMON Work Queues Latch

00000000861C0D00 5006 1 0 0 0 0 DMON Work Queues Latch

00000000861C0D20 5007 1 0 0 0 0 DMON Work Queues Latch

00000000861C0D40 5008 1 0 0 0 0 DMON Work Queues Latch

00000000861C0D60 5009 1 0 0 0 0 DMON Work Queues Latch

00000000861C0D80 5010 1 0 0 0 0 DMON Work Queues Latch

00000000861C0DA0 5011 1 0 0 0 0 DMON Work Queues Latch

00000000861C0DC0 5012 1 0 0 0 0 DMON Work Queues Latch

00000000861C0DE0 5013 1 0 0 0 0 DMON Work Queues Latch

00000000861C0E00 5014 1 0 0 0 0 DMON Work Queues Latch

00000000861C0E20 5015 1 0 0 0 0 DMON Work Queues Latch

00000000861C0E40 5016 1 0 0 0 0 DMON Work Queues Latch

00000000861C0E60 5017 1 0 0 0 0 DMON Work Queues Latch

46 rows selected.

--//可以看出取值在4972-5017之間.

SYS@book> select * from x$ksllw where indx between 4972 and 5017;

ADDR INDX INST_ID KSLLWNAM KSLLWLBL

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

0000000009AB0CC0 4972 1 rfifdrcxch

0000000009AB0CD0 4973 1 rfifreqch

0000000009AB0CE0 4974 1 rfm_do_hc

0000000009AB0CF0 4975 1 rfm_init_boot_te1

0000000009AB0D00 4976 1 rfm_init_boot_te2

0000000009AB0D10 4977 1 rfm_init_boot_te3

0000000009AB0D20 4978 1 rfm_init_boot_te4

0000000009AB0D30 4979 1 rfm_free_te

0000000009AB0D40 4980 1 rfm_setup_te

0000000009AB0D50 4981 1 rfmeadvphs

0000000009AB0D60 4982 1 rfmdophs

0000000009AB0D70 4983 1 rfmdolocalop

0000000009AB0D80 4984 1 rfmdowrop1

0000000009AB0D90 4985 1 rfmdowrop2

0000000009AB0DA0 4986 1 rfmdowrop3

0000000009AB0DB0 4987 1 rfmdomonproperty1

0000000009AB0DC0 4988 1 rfmdomonproperty2

0000000009AB0DD0 4989 1 rfm_init_boot_te5

0000000009AB0DE0 4990 1 rfmdoremoteop1

0000000009AB0DF0 4991 1 rfmdoremoteop2

0000000009AB0E00 4992 1 rfmdodisable

0000000009AB0E10 4993 1 rfm_do_switchover1

0000000009AB0E20 4994 1 rfm_do_switchover2

0000000009AB0E30 4995 1 rfm_do_failover

0000000009AB0E40 4996 1 rfmtecb1

0000000009AB0E50 4997 1 rfmtecb2

0000000009AB0E60 4998 1 rfm_quiesce_site

0000000009AB0E70 4999 1 rfm_quiesce_instance

0000000009AB0E80 5000 1 rfm_enable_object

0000000009AB0E90 5001 1 rfmdsite

0000000009AB0EA0 5002 1 rfm_execute_task_fn1

0000000009AB0EB0 5003 1 rfm_execute_task_fn2

0000000009AB0EC0 5004 1 rfm_inst_phase_dispatch1

0000000009AB0ED0 5005 1 rfm_inst_phase_dispatch2

0000000009AB0EE0 5006 1 rfm_inst_phase_dispatch3

0000000009AB0EF0 5007 1 rfm_get_chief_lock

0000000009AB0F00 5008 1 rfm_release_chief_lock

0000000009AB0F10 5009 1 rfmhcadvphs

0000000009AB0F20 5010 1 rfm_do_client_hc

0000000009AB0F30 5011 1 rfm_execute_sprobe

0000000009AB0F40 5012 1 rfm_broker_cleanup

0000000009AB0F50 5013 1 rfm_init_dmon

0000000009AB0F60 5014 1 rfrm_set_param

0000000009AB0F70 5015 1 rfm_init_boot_te6

0000000009AB0F80 5016 1 rfm_phase_dispatch_sby1

0000000009AB0F90 5017 1 rfm_phase_dispatch_sby2

46 rows selected.

--//KSLLWNAM 對應的就是location.透過gV$LATCH_MISSES 定義修改一下增加indx如下:

/* Formatted on 2019/4/9 12:10:49 (QP5 v5.269.14213.34769) */

SELECT t1.inst_id inst_id

,t1.indx indx

,t1.ksllasnam PARENT_NAME

,t2.ksllwnam "WHERE"

,t1.kslnowtf NWFAIL_COUNT

,t1.kslsleep SLEEP_COUNT

,t1.kslwscwsl WTR_SLP_COUNT

,t1.kslwsclthg LONGHOLD_COUNT

,t2.ksllwnam LOCATION

FROM x$ksllw t2, x$kslwsc t1

WHERE t2.indx = t1.indx AND t1.ksllasnam LIKE 'DMON Work Queues Latch';

--//location 與where 對應的內容一樣.

INST_ID INDX PARENT_NAME WHERE NWFAIL_COUNT SLEEP_COUNT WTR_SLP_COUNT LONGHOLD_COUNT LOCATION

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

1 4972 DMON Work Queues Latch rfifdrcxch 0 1 1 0 rfifdrcxch

1 4973 DMON Work Queues Latch rfifreqch 0 0 0 0 rfifreqch

1 4974 DMON Work Queues Latch rfm_do_hc 0 0 0 0 rfm_do_hc

1 4975 DMON Work Queues Latch rfm_init_boot_te1 0 0 0 0 rfm_init_boot_te1

1 4976 DMON Work Queues Latch rfm_init_boot_te2 0 0 0 0 rfm_init_boot_te2

1 4977 DMON Work Queues Latch rfm_init_boot_te3 0 0 0 0 rfm_init_boot_te3

1 4978 DMON Work Queues Latch rfm_init_boot_te4 0 0 0 0 rfm_init_boot_te4

1 4979 DMON Work Queues Latch rfm_free_te 0 0 0 0 rfm_free_te

1 4980 DMON Work Queues Latch rfm_setup_te 0 0 0 0 rfm_setup_te

1 4981 DMON Work Queues Latch rfmeadvphs 0 0 0 0 rfmeadvphs

1 4982 DMON Work Queues Latch rfmdophs 0 0 0 0 rfmdophs

1 4983 DMON Work Queues Latch rfmdolocalop 0 0 0 0 rfmdolocalop

1 4984 DMON Work Queues Latch rfmdowrop1 0 0 0 0 rfmdowrop1

1 4985 DMON Work Queues Latch rfmdowrop2 0 0 0 0 rfmdowrop2

1 4986 DMON Work Queues Latch rfmdowrop3 0 0 0 0 rfmdowrop3

1 4987 DMON Work Queues Latch rfmdomonproperty1 0 0 0 0 rfmdomonproperty1

1 4988 DMON Work Queues Latch rfmdomonproperty2 0 0 0 0 rfmdomonproperty2

1 4989 DMON Work Queues Latch rfm_init_boot_te5 0 0 0 0 rfm_init_boot_te5

1 4990 DMON Work Queues Latch rfmdoremoteop1 0 0 0 0 rfmdoremoteop1

1 4991 DMON Work Queues Latch rfmdoremoteop2 0 0 0 0 rfmdoremoteop2

1 4992 DMON Work Queues Latch rfmdodisable 0 0 0 0 rfmdodisable

1 4993 DMON Work Queues Latch rfm_do_switchover1 0 0 0 0 rfm_do_switchover1

1 4994 DMON Work Queues Latch rfm_do_switchover2 0 0 0 0 rfm_do_switchover2

1 4995 DMON Work Queues Latch rfm_do_failover 0 0 0 0 rfm_do_failover

1 4996 DMON Work Queues Latch rfmtecb1 0 0 0 0 rfmtecb1

1 4997 DMON Work Queues Latch rfmtecb2 0 0 0 0 rfmtecb2

1 4998 DMON Work Queues Latch rfm_quiesce_site 0 0 0 0 rfm_quiesce_site

1 4999 DMON Work Queues Latch rfm_quiesce_instance 0 0 0 0 rfm_quiesce_instance

1 5000 DMON Work Queues Latch rfm_enable_object 0 0 0 0 rfm_enable_object

1 5001 DMON Work Queues Latch rfmdsite 0 0 0 0 rfmdsite

1 5002 DMON Work Queues Latch rfm_execute_task_fn1 0 0 0 0 rfm_execute_task_fn1

1 5003 DMON Work Queues Latch rfm_execute_task_fn2 0 0 0 0 rfm_execute_task_fn2

1 5004 DMON Work Queues Latch rfm_inst_phase_dispatch1 0 0 0 0 rfm_inst_phase_dispatch1

1 5005 DMON Work Queues Latch rfm_inst_phase_dispatch2 0 0 0 0 rfm_inst_phase_dispatch2

1 5006 DMON Work Queues Latch rfm_inst_phase_dispatch3 0 0 0 0 rfm_inst_phase_dispatch3

1 5007 DMON Work Queues Latch rfm_get_chief_lock 0 0 0 0 rfm_get_chief_lock

1 5008 DMON Work Queues Latch rfm_release_chief_lock 0 0 0 0 rfm_release_chief_lock

1 5009 DMON Work Queues Latch rfmhcadvphs 0 0 0 0 rfmhcadvphs

1 5010 DMON Work Queues Latch rfm_do_client_hc 0 0 0 0 rfm_do_client_hc

1 5011 DMON Work Queues Latch rfm_execute_sprobe 0 0 0 0 rfm_execute_sprobe

1 5012 DMON Work Queues Latch rfm_broker_cleanup 0 0 0 0 rfm_broker_cleanup

1 5013 DMON Work Queues Latch rfm_init_dmon 0 0 0 0 rfm_init_dmon

1 5014 DMON Work Queues Latch rfrm_set_param 0 0 0 0 rfrm_set_param

1 5015 DMON Work Queues Latch rfm_init_boot_te6 0 0 0 0 rfm_init_boot_te6

1 5016 DMON Work Queues Latch rfm_phase_dispatch_sby1 0 0 0 0 rfm_phase_dispatch_sby1

1 5017 DMON Work Queues Latch rfm_phase_dispatch_sby2 0 0 0 0 rfm_phase_dispatch_sby2

46 rows selected.

3.where的取值:

--//3-where (X$KSLLW.INDX)

SYS@book> select * from X$KSLLW where indx between 4972 and 5017 ;

ADDR INDX INST_ID KSLLWNAM KSLLWLBL

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

0000000009AB0CC0 4972 1 rfifdrcxch

0000000009AB0CD0 4973 1 rfifreqch

0000000009AB0CE0 4974 1 rfm_do_hc

0000000009AB0CF0 4975 1 rfm_init_boot_te1

0000000009AB0D00 4976 1 rfm_init_boot_te2

0000000009AB0D10 4977 1 rfm_init_boot_te3

0000000009AB0D20 4978 1 rfm_init_boot_te4

0000000009AB0D30 4979 1 rfm_free_te

0000000009AB0D40 4980 1 rfm_setup_te

0000000009AB0D50 4981 1 rfmeadvphs

0000000009AB0D60 4982 1 rfmdophs

0000000009AB0D70 4983 1 rfmdolocalop

0000000009AB0D80 4984 1 rfmdowrop1

0000000009AB0D90 4985 1 rfmdowrop2

0000000009AB0DA0 4986 1 rfmdowrop3

0000000009AB0DB0 4987 1 rfmdomonproperty1

0000000009AB0DC0 4988 1 rfmdomonproperty2

0000000009AB0DD0 4989 1 rfm_init_boot_te5

0000000009AB0DE0 4990 1 rfmdoremoteop1

0000000009AB0DF0 4991 1 rfmdoremoteop2

0000000009AB0E00 4992 1 rfmdodisable

0000000009AB0E10 4993 1 rfm_do_switchover1

0000000009AB0E20 4994 1 rfm_do_switchover2

0000000009AB0E30 4995 1 rfm_do_failover

0000000009AB0E40 4996 1 rfmtecb1

0000000009AB0E50 4997 1 rfmtecb2

0000000009AB0E60 4998 1 rfm_quiesce_site

0000000009AB0E70 4999 1 rfm_quiesce_instance

0000000009AB0E80 5000 1 rfm_enable_object

0000000009AB0E90 5001 1 rfmdsite

0000000009AB0EA0 5002 1 rfm_execute_task_fn1

0000000009AB0EB0 5003 1 rfm_execute_task_fn2

0000000009AB0EC0 5004 1 rfm_inst_phase_dispatch1

0000000009AB0ED0 5005 1 rfm_inst_phase_dispatch2

0000000009AB0EE0 5006 1 rfm_inst_phase_dispatch3

0000000009AB0EF0 5007 1 rfm_get_chief_lock

0000000009AB0F00 5008 1 rfm_release_chief_lock

0000000009AB0F10 5009 1 rfmhcadvphs

0000000009AB0F20 5010 1 rfm_do_client_hc

0000000009AB0F30 5011 1 rfm_execute_sprobe

0000000009AB0F40 5012 1 rfm_broker_cleanup

0000000009AB0F50 5013 1 rfm_init_dmon

0000000009AB0F60 5014 1 rfrm_set_param

0000000009AB0F70 5015 1 rfm_init_boot_te6

0000000009AB0F80 5016 1 rfm_phase_dispatch_sby1

0000000009AB0F90 5017 1 rfm_phase_dispatch_sby2

46 rows selected.

--//感覺不對,不大可能還是indx.

--//連結

Also, these strings present as "Location from where latch is held" in process state object dumps. For example, look

at the process holding cache buffers chains latch:

--//此外，這些字串在程式狀態物件轉儲中以"持有鎖的位置"的形式出現。例如，檢視儲存緩衝區鏈鎖存的程式：

PROCESS 299:

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

SO: 0x2d93be720, type: 2, owner: (nil), flag: INIT/-/-/0x00

(process) Oracle pid=299, calls cur/top: 0x2e9028a38/0x2e9028a38, flag: (0)

…

(latch info) wait_event=0 bits=2

holding 2dee1ac50 Child cache buffers chains level=1 child#=124200

Location from where latch is held: kcbgtcr: fast path:

Context saved from call: 39022946

…

"Why" meaning for some of "where" may be guessed from ksllwlbl column of x$ksllw. From the above listing one can

conclude that "why" contain the SGA chunk address for shared pool latch and the session address for session idle bit

latch correspondingly.

--//從x$ksllw的ksllwlbl列中可以猜到"why"的意思是"WHERE"。從上面的列表中可以得出結論，"why"包含用於共享池閂鎖的SGA塊地址

--//，以及相應地包含會話空閒位閂鎖的會話地址。

--//KSLLWLBL列顯示的是空?視乎要按照上下文猜測why.

[20190409]latch get 引數where and why.txt

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