Oracle 10.2.0.4 library cache contention,every event wait 64s! strange

my database suddently very slow in a few seconds.After a while, all become normal.
In awr report,I find no special sql.
I paste two trouble time awr report here.
If you have any more information for troubleshooting ,I will paste if you require.
Thanks.
AWR report1:
WORKLOAD REPOSITORY report for
DB Name DB Id Instance Inst Num Release RAC Host
DB 3594421410 db2 2 10.2.0.4.0 YES db2
Snap Id Snap Time Sessions Curs/Sess
Begin Snap: 2342 17-Mar-09 21:30:23 521 1.1
End Snap: 2344 17-Mar-09 22:30:25 498 1.0
Elapsed: 60.03 (mins)
DB Time: 750.95 (mins)
Cache Sizes
~~~~~~~~~~~ Begin End
Buffer Cache: 3,504M 3,504M Std Block Size: 8K
Shared Pool Size: 1,200M 1,200M Log Buffer: 14,340K
Load Profile
~~~~~~~~~~~~ Per Second Per Transaction
Redo size: 18,182.64 2,754.51
Logical reads: 326.19 49.41
Block changes: 123.54 18.72
Physical reads: 21.33 3.23
Physical writes: 7.29 1.10
User calls: 178.46 27.03
Parses: 62.04 9.40
Hard parses: 0.09 0.01
Sorts: 2.00 0.30
Logons: 0.20 0.03
Executes: 63.12 9.56
Transactions: 6.60
% Blocks changed per Read: 37.87 Recursive Call %: 17.93
Rollback per transaction %: 14.26 Rows per Sort: 44.63
Instance Efficiency Percentages (Target 100%)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Buffer Nowait %: 99.99 Redo NoWait %: 99.95
Buffer Hit %: 93.46 In-memory Sort %: 100.00
Library Hit %: 99.52 Soft Parse %: 99.86
Execute to Parse %: 1.70 Latch Hit %: 99.97
Parse CPU to Parse Elapsd %: 0.82 % Non-Parse CPU: 98.60
Shared Pool Statistics Begin End
Memory Usage %: 78.60 78.77
% SQL with executions>1: 99.38 99.27
% Memory for SQL w/exec>1: 99.00 98.78
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time Wait Class
latch: library cache 736 47,078 63965 104.5 Concurrenc
CPU time 236 0.5
rdbms ipc reply 360 219 608 0.5 Other
log file sync 20,469 137 7 0.3 Commit
gc cr block 2-way 35,641 102 3 0.2 Cluster
AWR report 2:
DB Name DB Id Instance Inst Num Release RAC Host
db 3594421410 db2 2 10.2.0.4.0 YES yt-db2
Snap Id Snap Time Sessions Curs/Sess
Begin Snap: 2364 18-Mar-09 08:30:29 497 1.1
End Snap: 2365 18-Mar-09 08:42:28 511 1.0
Elapsed: 11.99 (mins)
DB Time: 277.14 (mins)
Cache Sizes
~~~~~~~~~~~ Begin End
Buffer Cache: 3,504M 3,504M Std Block Size: 8K
Shared Pool Size: 1,200M 1,200M Log Buffer: 14,340K
Load Profile
~~~~~~~~~~~~ Per Second Per Transaction
Redo size: 23,306.73 2,556.74
Logical reads: 337.31 37.00
Block changes: 159.74 17.52
Physical reads: 0.72 0.08
Physical writes: 9.74 1.07
User calls: 274.07 30.06
Parses: 95.29 10.45
Hard parses: 0.04 0.00
Sorts: 2.52 0.28
Logons: 0.19 0.02
Executes: 95.71 10.50
Transactions: 9.12
% Blocks changed per Read: 47.36 Recursive Call %: 9.14
Rollback per transaction %: 11.13 Rows per Sort: 32.48
Instance Efficiency Percentages (Target 100%)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Buffer Nowait %: 98.81 Redo NoWait %: 100.00
Buffer Hit %: 99.79 In-memory Sort %: 100.00
Library Hit %: 99.86 Soft Parse %: 99.95
Execute to Parse %: 0.44 Latch Hit %: 99.94
Parse CPU to Parse Elapsd %: 40.91 % Non-Parse CPU: 81.90
Shared Pool Statistics Begin End
Memory Usage %: 79.91 80.01
% SQL with executions>1: 99.52 99.52
% Memory for SQL w/exec>1: 98.83 98.77
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time Wait Class
latch free 176 4,391 24950 26.4 Other
gc buffer busy 3,726 3,335 895 20.1 Cluster
gc cr multi block request 4,165 2,204 529 13.3 Cluster
gc current grant busy 3,938 1,798 457 10.8 Cluster
latch: cache buffers chains 124 1,548 12487 9.3 Concurrenc
^LRAC Statistics DB/Inst: db/db2 Snaps: 2364-2365
Begin End
Number of Instances: 2 2
Global Cache Load Profile
~~~~~~~~~~~~~~~~~~~~~~~~~ Per Second Per Transaction
Global Cache blocks received: 19.36 2.12
Global Cache blocks served: 19.39 2.13
GCS/GES messages received: 63.76 6.99
GCS/GES messages sent: 63.64 6.98
DBWR Fusion writes: 2.58 0.28
Estd Interconnect traffic (KB) 334.84
Edited by: gaoyafang on 2009-3-18 上午12:46

my database suddently very slow in a few seconds.After a while, all become normal.
In awr report,I find no special sql.
I paste two trouble time awr report here.
If you have any more information for troubleshooting ,I will paste if you require.
Thanks.
AWR report1:
WORKLOAD REPOSITORY report for
DB Name DB Id Instance Inst Num Release RAC Host
DB 3594421410 db2 2 10.2.0.4.0 YES db2
Snap Id Snap Time Sessions Curs/Sess
Begin Snap: 2342 17-Mar-09 21:30:23 521 1.1
End Snap: 2344 17-Mar-09 22:30:25 498 1.0
Elapsed: 60.03 (mins)
DB Time: 750.95 (mins)
Cache Sizes
~~~~~~~~~~~ Begin End
Buffer Cache: 3,504M 3,504M Std Block Size: 8K
Shared Pool Size: 1,200M 1,200M Log Buffer: 14,340K
Load Profile
~~~~~~~~~~~~ Per Second Per Transaction
Redo size: 18,182.64 2,754.51
Logical reads: 326.19 49.41
Block changes: 123.54 18.72
Physical reads: 21.33 3.23
Physical writes: 7.29 1.10
User calls: 178.46 27.03
Parses: 62.04 9.40
Hard parses: 0.09 0.01
Sorts: 2.00 0.30
Logons: 0.20 0.03
Executes: 63.12 9.56
Transactions: 6.60
% Blocks changed per Read: 37.87 Recursive Call %: 17.93
Rollback per transaction %: 14.26 Rows per Sort: 44.63
Instance Efficiency Percentages (Target 100%)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Buffer Nowait %: 99.99 Redo NoWait %: 99.95
Buffer Hit %: 93.46 In-memory Sort %: 100.00
Library Hit %: 99.52 Soft Parse %: 99.86
Execute to Parse %: 1.70 Latch Hit %: 99.97
Parse CPU to Parse Elapsd %: 0.82 % Non-Parse CPU: 98.60
Shared Pool Statistics Begin End
Memory Usage %: 78.60 78.77
% SQL with executions>1: 99.38 99.27
% Memory for SQL w/exec>1: 99.00 98.78
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time Wait Class
latch: library cache 736 47,078 63965 104.5 Concurrenc
CPU time 236 0.5
rdbms ipc reply 360 219 608 0.5 Other
log file sync 20,469 137 7 0.3 Commit
gc cr block 2-way 35,641 102 3 0.2 Cluster
AWR report 2:
DB Name DB Id Instance Inst Num Release RAC Host
db 3594421410 db2 2 10.2.0.4.0 YES yt-db2
Snap Id Snap Time Sessions Curs/Sess
Begin Snap: 2364 18-Mar-09 08:30:29 497 1.1
End Snap: 2365 18-Mar-09 08:42:28 511 1.0
Elapsed: 11.99 (mins)
DB Time: 277.14 (mins)
Cache Sizes
~~~~~~~~~~~ Begin End
Buffer Cache: 3,504M 3,504M Std Block Size: 8K
Shared Pool Size: 1,200M 1,200M Log Buffer: 14,340K
Load Profile
~~~~~~~~~~~~ Per Second Per Transaction
Redo size: 23,306.73 2,556.74
Logical reads: 337.31 37.00
Block changes: 159.74 17.52
Physical reads: 0.72 0.08
Physical writes: 9.74 1.07
User calls: 274.07 30.06
Parses: 95.29 10.45
Hard parses: 0.04 0.00
Sorts: 2.52 0.28
Logons: 0.19 0.02
Executes: 95.71 10.50
Transactions: 9.12
% Blocks changed per Read: 47.36 Recursive Call %: 9.14
Rollback per transaction %: 11.13 Rows per Sort: 32.48
Instance Efficiency Percentages (Target 100%)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Buffer Nowait %: 98.81 Redo NoWait %: 100.00
Buffer Hit %: 99.79 In-memory Sort %: 100.00
Library Hit %: 99.86 Soft Parse %: 99.95
Execute to Parse %: 0.44 Latch Hit %: 99.94
Parse CPU to Parse Elapsd %: 40.91 % Non-Parse CPU: 81.90
Shared Pool Statistics Begin End
Memory Usage %: 79.91 80.01
% SQL with executions>1: 99.52 99.52
% Memory for SQL w/exec>1: 98.83 98.77
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time Wait Class
latch free 176 4,391 24950 26.4 Other
gc buffer busy 3,726 3,335 895 20.1 Cluster
gc cr multi block request 4,165 2,204 529 13.3 Cluster
gc current grant busy 3,938 1,798 457 10.8 Cluster
latch: cache buffers chains 124 1,548 12487 9.3 Concurrenc
^LRAC Statistics DB/Inst: db/db2 Snaps: 2364-2365
Begin End
Number of Instances: 2 2
Global Cache Load Profile
~~~~~~~~~~~~~~~~~~~~~~~~~ Per Second Per Transaction
Global Cache blocks received: 19.36 2.12
Global Cache blocks served: 19.39 2.13
GCS/GES messages received: 63.76 6.99
GCS/GES messages sent: 63.64 6.98
DBWR Fusion writes: 2.58 0.28
Estd Interconnect traffic (KB) 334.84
Edited by: gaoyafang on 2009-3-18 上午12:46

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                0 7bf20060 7bf28ba8 I/P/A/-/-    0 NONE   00
                6 7bf77a20 7bf776f8 I/P/A/-/-    1 NONE   00
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          call pin=(nil) session pin=(nil) hpc=0000 hlc=0000
          htl=0x7d03b6a0[0x7d034030,0x7c03c9f8] htb=0x7d034030 ssga=0x7e9f2168
          user=84f5b4a8 session=84f5b4a8 count=1 flags=[0000] savepoint=0x1f7
          LIBRARY OBJECT HANDLE: handle=7bf10088 mutex=0x7bf101b8(0)
          name=select 1 from maclean where rownum=1
          hash=324793c639b13d0954bd5421eaed6701 timestamp=03-08-2012 02:29:24
          namespace=CRSR flags=RON/KGHP/TIM/KEP/PN0/SML/DBN/[12010044]
          kkkk-dddd-llll=0001-0001-0001 lock=N pin=0 latch#=3 hpc=0004 hlc=0004
          lwt=0x7bf10130[0x7bf10130,0x7bf10130] ltm=0x7bf10140[0x7bf10140,0x7bf10140]
          pwt=0x7bf100f8[0x7bf100f8,0x7bf100f8] ptm=0x7bf10108[0x7bf10108,0x7bf10108]
          ref=0x7bf10160[0x7bf10160,0x7bf10160] lnd=0x7bf10178[0x82f4f2f8,0x7bf4d608]
            LIBRARY OBJECT: object=7bf7c8a8
            type=CRSR flags=EXS[0001] pflags=[0000] status=VALD load=0
            CHILDREN: size=16
            child#    table reference   handle
                 0 7bf7c370  7bf7bfe0 7bf46e40                           => 只有一个child  handle 7bf46e40                          
            DATA BLOCKS:
            data#     heap  pointer    status pins change whr
                0 7bf2a428 7bf7c9c0 I/P/A/-/-    0 NONE   00即在session B parse SQL "select 1 from maclean where rownum=1" 的时候， 会生成一个child cursor 并 X mode pin住这个child cursor ， 而session C 同时发起 一样的SQL语句 "select 1 from maclean where rownum=1" 时 需要 share 这个child cursor ， 即以 S mode pin 这个child cursor ， 但是session B 还没有完成 optimize 没有生成完整的child cursor ， 需要等待 session A 释放 library cache lock才能 完成， 所以 session C 要等 session B build child cursor ， 此时session C等" library cache pin" ；
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    since 10.2.0.3 "_kks_use_mutex_pin"=TRUE or 11g 开始 使用mutex 保护cursor pin ，所以 session C 若执行 与session B 一样的SQL，那么 wiat for cursor pin S on X
    SQL> select * from V$version;
    BANNER
    Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
    PL/SQL Release 11.2.0.3.0 - Production
    CORE 11.2.0.3.0 Production
    TNS for Linux: Version 11.2.0.3.0 - Production
    NLSRTL Version 11.2.0.3.0 - Production
    session A:
    SQL> alter table test add t11 char(2000) default 'maclean';
    session B:
    SQL> select * from test where rownum=1;
    session C:
    SQL> select * from test where rownum=1;
    SQL> select event from v$session where wait_class='Concurrency';
    EVENT
    cursor: pin S wait on X
    library cache lock
    SQL> oradebug setmypid;
    Statement processed.
    SQL> oradebug dump systemstate 266;
    Statement processed.
    session C:
    SO: 0x9e2256b8, type: 4, owner: 0x9e59a1c0, flag: INIT/-/-/0x00 if: 0x3 c: 0x3
    proc=0x9e59a1c0, name=session, file=ksu.h LINE:12624, pg=0
    (session) sid: 179 ser: 41307 trans: (nil), creator: 0x9e59a1c0
    flags: (0x41) USR/- flags_idl: (0x1) BSY/-/-/-/-/-
    flags2: (0x40009) -/-/INC
    DID: , short-term DID:
    txn branch: (nil)
    oct: 3, prv: 0, sql: 0x956e18b8, psql: 0x956e18b8, user: 0/SYS
    ksuxds FALSE at location: 0
    service name: SYS$USERS
    client details:
    O/S info: user: oracle, term: pts/3, ospid: 26823
    machine: vrh1.oracle.com program: [email protected] (TNS V1-V3)
    application name: [email protected] (TNS V1-V3), hash value=1481565533
    Current Wait Stack:
    0: waiting for 'cursor: pin S wait on X'
    idn=0xe76d0d8c, value=0xca00000000, where=0x500000000
    wait_id=17 seq_num=18 snap_id=1
    wait times: snap=12.671273 sec, exc=12.671273 sec, total=12.671273 sec
    wait times: max=infinite, heur=12.671273 sec
    wait counts: calls=1148 os=1148
    in_wait=1 iflags=0x15b2
    There is at least one session blocking this session.
    Dumping 1 direct blocker(s):
    inst: 1, sid: 202, ser: 15511
    Dumping final blocker:
    inst: 1, sid: 9, ser: 1
    Wait State:
    fixed_waits=0 flags=0x22 boundary=(nil)/-1
    idn=0xe76d0d8c=> 这个是mutex的标示
    KGX Atomic Operation Log 0x94aa8ca8
    Mutex 0x8a328978(202, 0) idn e76d0d8c oper GET_SHRD
    Cursor Pin uid 179 efd 0 whr 5 slp 1148
    opr=2 pso=0x8b5a8c48 flg=0
    pcs=0x8a3288e0 nxt=(nil) flg=35 cld=1 hd=0x93d4bbb8 par=0x8a328048
    ct=1 hsh=0 unp=(nil) unn=0 hvl=8a328ef0 nhv=1 ses=0x9e1e0ea0
    hep=0x8a328978 flg=80 ld=1 ob=0x939a30b0 ptr=0x935e0348 fex=0x935df6f0
    这个mutex的 oper是 GET_SHRD 即 pin S 它指向 0x93d4bbb8 是一个child cursor
    以下是parent cursor:
    SO: 0x957fa9d8, type: 78, owner: 0x9e1e0ea0, flag: INIT/-/-/0x00 if: 0x3 c: 0x3
    proc=0x9e593da0, name=LIBRARY OBJECT LOCK, file=kgl.h LINE:8547, pg=0
    LibraryObjectLock: Address=0x957fa9d8 Handle=0x956e18b8 Mode=N CanBeBrokenCount=1 Incarnation=1 ExecutionCount=0
    User=0x9e1e0ea0 Session=0x9e1e0ea0 ReferenceCount=1 Flags=CNB/[0001] SavepointNum=4f5864b8
    LibraryHandle: Address=0x956e18b8 Hash=e76d0d8c LockMode=N PinMode=0 LoadLockMode=0 Status=VALD
    ObjectName: Name=select * from test where rownum=1
    FullHashValue=7e277fabf95d7c80e8924ed6e76d0d8c Namespace=SQL AREA(00) Type=CURSOR(00) Identifier=3882683788 OwnerIdn=0
    Statistics: InvalidationCount=1 ExecutionCount=2 LoadCount=3 ActiveLocks=2 TotalLockCount=4 TotalPinCount=1
    Counters: BrokenCount=1 RevocablePointer=1 KeepDependency=1 BucketInUse=3 HandleInUse=3 HandleReferenceCount=0
    Concurrency: DependencyMutex=0x956e1968(0, 2, 0, 0) Mutex=0x956e19e8(0, 45, 0, 0)
    Flags=RON/PIN/TIM/PN0/DBN/[10012841]
    WaitersLists:
    Lock=0x956e1948[0x956e1948,0x956e1948]
    Pin=0x956e1928[0x956e1928,0x956e1928]
    LoadLock=0x956e19a0[0x956e19a0,0x956e19a0]
    Timestamp: Current=03-08-2012 02:45:45
    HandleReference: Address=0x956e1a78 Handle=(nil) Flags=[00]
    LibraryObject: Address=0x8a327fa8 HeapMask=0000-0001-0001-0000 Flags=EXS[0000] Flags2=[0000] PublicFlags=[0000]
    ChildTable: size='16'
    Child: id='0' Table=0x8a328e58 Reference=0x8a3288b8 Handle=0x956db988
    Child: id='1' Table=0x8a328e58 Reference=0x8a328b80 Handle=0x93d4bbb8
    NamespaceDump:
    Parent Cursor: sql_id=fj4kfuvmqu3cc parent=0x8a328048 maxchild=2 plk=y ppn=n
    但是很可惜 0x93d4bbb8 这个 child cursor 被 session B pin住了：
    SO: 0x957fa8d8, type: 78, owner: 0x9e1e0ea0, flag: INIT/-/-/0x00 if: 0x3 c: 0x3
    proc=0x9e593da0, name=LIBRARY OBJECT LOCK, file=kgl.h LINE:8547, pg=0
    LibraryObjectLock: Address=0x957fa8d8 Handle=0x93d4bbb8 Mode=N CanBeBrokenCount=1 Incarnation=1 ExecutionCount=0
    ClusterLock=0x8f1945f8 Context=0x7fd379518308 User=0x9e1e0ea0 Session=0x9e1e0ea0 ReferenceCount=1
    Flags=CBK/[0020] SavepointNum=0
    LibraryHandle: Address=0x93d4bbb8 Hash=0 LockMode=N PinMode=X LoadLockMode=0 Status=VALD
    Name: Namespace=SQL AREA(00) Type=CURSOR(00)
    Statistics: InvalidationCount=0 ExecutionCount=0 LoadCount=1 ActiveLocks=2 TotalLockCount=2 TotalPinCount=3
    Counters: BrokenCount=1 RevocablePointer=1 KeepDependency=0 BucketInUse=0 HandleInUse=0 HandleReferenceCount=0
    Concurrency: DependencyMutex=0x93d4bc68(0, 0, 0, 0) Mutex=0x956e19e8(0, 45, 0, 0)
    Flags=RON/PIN/PN0/EXP/CHD/[10012111]
    WaitersLists:
    Lock=0x93d4bc48[0x93d4bc48,0x93d4bc48]
    Pin=0x93d4bc28[0x93d4bc28,0x93d4bc28]
    LoadLock=0x93d4bca0[0x93d4bca0,0x93d4bca0]
    LibraryObject: Address=0x939a30b0 HeapMask=0000-0001-0001-0000 Flags=EXS[0000] Flags2=[0000] PublicFlags=[0000]
    DataBlocks:
    Block: #='0' name=KGLH0^e76d0d8c pins=0 Change=NONE
    Heap=0x93d1a808 Pointer=0x939a3150 Extent=0x939a3030 Flags=I/-/P/A/-/-
    FreedLocation=0 Alloc=1.546875 Size=4.000000 LoadTime=4385736620
    Block: #='6' name=SQLA^e76d0d8c pins=0 Change=NONE
    Heap=0x8a328a20 Pointer=0x935e0348 Extent=0x935df6f0 Flags=I/-/P/A/-/E
    FreedLocation=0 Alloc=0.000000 Size=0.000000 LoadTime=0
    NamespaceDump:
    Child Cursor: Heap0=0x939a3150 Heap6=0x935e0348 Heap0 Load Time=03-08-2012 02:50:16 Heap6 Load
    PinMode=X
    保持这个 X mode pin的是另外一个 mutex ， 这个mutex的 oper是 LONG_EXCL
    Time=03-08-2012 02:50:16 ----------------------------------------
    KGX Atomic Operation Log 0x8f1945f8
    Mutex 0x8a328978(202, 0) idn e76d0d8c oper LONG_EXCL
    Cursor Pin uid 202 efd 0 whr 1 slp 0
    opr=3 pso=0x957fa8d8 flg=0
    pcs=0x8a3288e0 nxt=(nil) flg=35 cld=1 hd=0x93d4bbb8 par=0x8a328048
    ct=1 hsh=0 unp=(nil) unn=0 hvl=8a328ef0 nhv=1 ses=0x9e1e0ea0
    hep=0x8a328978 flg=80 ld=1 ob=0x939a30b0 ptr=0x935e0348 fex=0x935df6f0

  • How to resolve Library Cache Pin waits?

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    Shiju

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  • Use of bind variables with the oracle db - to improve library cache perform

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    qj

    Generally, you would use bind variables by changing statements that are written like this
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  • Accessing downloaded content in../Library/Caches with LoaderMax

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                                  var queue:LoaderMax = new LoaderMax({name:"soundQueue", onComplete:loopSoundsCompleteHandler, onError:errorHandler});
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    With AIR 3.6 latest prerelease, A new static property, File.cacheDirectory has been added, which points to the <APPLICATION_HOME>/Library/Caches directory on iOS devices, and files in this directory are not backed up. So, the above workaround is not required.
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  • Oracle RAC 9i LMD library cache lock top wait event

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    There is a new patch for this - check out p4673610 on metalink. We have also experience the problem in 9.2.0.8.

  • High library cache load lock waits in AWR

    Hi All,
    Today i faced a significant performance problem related to shared pool. I made some observations, thought it would be a nice idea to share them with Oracle experts. Please feel free to add your observations/recommendations and correct me where i am wrong.
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    Snap Id Snap Time Sessions Cursors/Session
    Begin Snap: 9994 29-Jun-09 10:00:07 672 66.3
    End Snap: 10001 29-Jun-09 17:00:49 651 64.4
    Elapsed:   420.70 (mins)    
    DB Time:   4,045.34 (mins)   -- Very poor response time visible from difference between DB time and elapsed time.
    Load Profile
    Per Second Per Transaction
    Redo size: 248,954.70 23,511.82
    Logical reads: 116,107.04 10,965.40
    Block changes: 1,357.13 128.17
    Physical reads: 125.49 11.85
    Physical writes: 51.49 4.86
    User calls: 224.69 21.22
    Parses: 235.22 22.21
    Hard parses: 4.83 0.46
    Sorts: 102.94 9.72
    Logons: 1.12 0.11
    Executes: 821.11 77.55
    Transactions: 10.59   -- User calls and Parse count are almost same, means most of the calls are for parse. Most of the parses are soft. Per transaction 22 parses are very high figure.
    -- Not much disk I/O activity. Most of the reads are being satisfy from memory.
    Instance Efficiency
    Buffer Nowait %: 100.00 Redo NoWait %: 100.00
    Buffer Hit %: 99.92 In-memory Sort %: 100.00
    Library Hit %: 98.92 Soft Parse %: 97.95
    Execute to Parse %: 71.35 Latch Hit %: 99.98
    Parse CPU to Parse Elapsd %: 16.82 % Non-Parse CPU: 91.41 -- Low execute to parse ratio denotes CPU is significantly busy in parsing. Soft Parse% showing, most of the parse are soft parses. It means we should concentrate on soft parsing activity.
    -- Parse CPU to Parse Elapsed % is quite low, means some bottleneck is there related to parsing. It could be a side-effect of huge parsing pressure. Like CPU cycles are not available.
    Shared Pool Statistics
    Begin End
    Memory Usage %: 81.01 81.92
    % SQL with executions>1: 88.51 86.93
    % Memory for SQL w/exec>1: 86.16 86.76 -- Shared Pool memory seems ok (in 80% range)
    -- 88% of the SQLs are repeating ones. It's a good sign.
    Top 5 Timed Events
    Event Waits Time(s) Avg Wait(ms) % Total Call Time Wait Class
    library cache load lock 24,243 64,286 2,652 26.5 Concurrency
    db file sequential read 1,580,769 42,267 27 17.4 User I/O
    CPU time   33,039   13.6  
    latch: library cache 53,013 29,194 551 12.0 Concurrency
    db file scattered read 151,669 13,550 89 5.6 User I/O Problem-1: Contention on Library cache: May be due to under-sized shared pool, incorrect parameters, poor application design, But since we already observed that most of the parses are soft parses and shared pool usgae in 80%, seems problem related to holding cursors. open_cursors/session_cached_cursors are red flags.
    Problem-2: User I/O, may be due to poor SQLs, I/O sub-system, or poor physical design (wrong indexes are being used as DB file seq reads)
    Wait Class
    Wait Class Waits %Time -outs Total Wait Time (s) Avg wait (ms) Waits /txn
    Concurrency 170,577 44.58 109,020 639 0.64
    User I/O 2,001,978 0.00 59,662 30 7.49
    System I/O 564,771 0.00 8,069 14 2.11
    Application 145,106 1.25 6,352 44 0.54
    Commit 176,671 0.37 4,528 26 0.66
    Other 27,557 6.31 2,532 92 0.10
    Network 6,862,704 0.00 696 0 25.68
    Configuration 3,858 3.71 141 37 0.01
    Wait Events
    Event Waits %Time -outs Total Wait Time (s) Avg wait (ms) Waits /txn
    library cache load lock 24,243 83.95 64,286 2652 0.09
    db file sequential read 1,580,769 0.00 42,267 27 5.91
    latch: library cache 53,013 0.00 29,194 551 0.20
    db file scattered read 151,669 0.00 13,550 89 0.57
    latch: shared pool 25,403 0.00 12,969 511 0.10
    log file sync 176,671 0.37 4,528 26 0.66
    enq: TM - contention 1,455 90.93 3,975 2732 0.01 Instance Activity Stats
    opened cursors cumulative 5,290,760 209.60 19.80
    parse count (failures) 6,181 0.24 0.02
    parse count (hard) 121,841 4.83 0.46
    parse count (total) 5,937,336 235.22 22.21
    parse time cpu 283,787 11.24 1.06
    parse time elapsed 1,687,096 66.84 6.31 Latch Activity
    library cache 85,042,375 0.15 0.43 29194 304,831 7.16
    library cache load lock 257,089 0.00 1.20 0 69,065 0.00
    library cache lock 41,467,300 0.02 0.07 6 2,714 0.07
    library cache lock allocation 730,422 0.00 0.44 0 0  
    library cache pin 28,453,986 0.01 0.16 8 167 0.00
    library cache pin allocation 509,000 0.00 0.38 0 0 Init.ora parameters
    cursor_sharing= EXACT
    open_cursors= 3000
    session_cached_cursors= 0
    -- open_cursors value is too high. I have checked that maximum usage by a single session is 12%.
    -- session_cached_cursors are 0 causing soft parsing. 500/600 is good number to start with.
    cursor_sharing exact may cause hard parses. But here, hard parsing is comparatively small, we can ignore this.
    From v$librarycache
    NAMESPACE             GETS    GETHITS GETHITRATIO       PINS PINHITRATIO    RELOADS INVALIDATIONS
    SQL AREA            162827      25127  .154317159  748901435  .999153087     107941         81886-- high invalidation count due to DDL like activities.
    -- high reloads due to small library cache.
    -- hit ratio too small.
    -- Need to pin frequently executed objects into library cache.
    P.S. Same question asked on Oracle_L, but due to formatting reasons, pasing duplicate contents here.
    Regards,
    Neeraj Bhatia
    Edited by: Neeraj.Bhatia2 on Jul 13, 2009 6:51 AM                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

    Thanks Charles. I really appreciate your efforts to diagnose the issue.
    I agree with you performance issue is caused by soft parsing, which can be solved by holding cursors (session_cached_cursors). It may be due to oversized shared pool, which is causing delay in searching child cursors.
    My second thought is, there is large number of reloads, which can be due to under-sized shared pool, if invalidation activities are not going (CBO statistics collection, DDL etc), cursors are being flushed frequently.
    CPU utilization is continuously high (above 90%). Pasting additional information from same AWR report.
    Namespace                Get Requests       Pct Miss        Pin Requests         Pct Miss      Reloads        Invalidations
    BODY                       225,345               0.76            4,965,541            0.15           5,533           0
    CLUSTER                   1,278                  1.41            2,542                  1.73           26                0
    INDEX                       5,982                  9.31            13,922                7.35           258               0
    SQL AREA                  141,465              54.10           27,831,235         1.21           69,863          19,085 Latch Miss Sources
    Latch Name             Where                                         NoWait Misses                 Sleeps             Waiter Sleeps
    library cache lock       kgllkdl: child: no lock handle             0                                   8,250                   5,792 Time Model Statistics
    Statistic Name                                                                           Time (s)                               % of DB Time
    sql execute elapsed time                                                           206,979.31                                      85.27
    PL/SQL execution elapsed time                                                    94,651.78                                      39.00
    DB CPU                                                                                     33,039.29                                      13.61
    parse time elapsed                                                                      22,635.47                                       9.33
    inbound PL/SQL rpc elapsed time                                                  14,763.48                                       6.08
    hard parse elapsed time                                                               14,136.77                                       5.82
    connection management call elapsed time                                        1,625.07                                       0.67
    PL/SQL compilation elapsed time                                                        760.76                                       0.31
    repeated bind elapsed time                                                               664.81                                       0.27
    hard parse (sharing criteria) elapsed time                                             500.11                                       0.21
    Java execution elapsed time                                                              252.95                                       0.10
    failed parse elapsed time                                                                   167.23                                       0.07
    hard parse (bind mismatch) elapsed time                                             124.11                                       0.05
    sequence load elapsed time                                                                23.34                                        0.01
    DB time                                                                                   242,720.12  
    background elapsed time                                                             11,645.52  
    background cpu time                                                                      247.25 According to this DB CPU is 65% utilization (DB CPU + Background CPU / Total Available CPU seconds). While at the same time DB host was 95% utilized (confirmed from DBA_HIST_SYSMETRIC_SUMMARY).
    Operating System Statistics
    Statistic                                         Total
    BUSY_TIME                             3,586,030
    IDLE_TIME                              1,545,064
    IOWAIT_TIME                              22,237
    NICE_TIME                                           0
    SYS_TIME                                  197,661
    USER_TIME                              3,319,452
    LOAD                                                 11
    RSRC_MGR_CPU_WAIT_TIME                  0
    PHYSICAL_MEMORY_BYTES          867,180
    NUM_CPUS                                           2

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