Prayer

測試環境：

db2 V9.5

 

參考書籍《db2數據庫性能調整和優化》牛新莊著  242頁

 

還是利用上一篇引起死鎖的那個表，來測試如果找到引起鎖等待的sql語句，為了模擬效果，設置locktimeout為-1

 

還是打開三個窗口,

窗口1：

$ db2 +c "insert into deadtable values(1)"
DB20000I  The SQL command completed successfully.

窗口2：

$ db2 +c "select * from deadtable"

引起等待

 

窗口3：

打開snapshot監控，重置計數器

 

$ db2 get snapshot for database on sample|grep -i lock
Locks held currently                       = 7
Lock waits                                 = 0
Time database waited on locks (ms)         = 555940
Lock list memory in use (Bytes)            = 5632
Deadlocks detected                         = 0
Lock escalations                           = 0
Exclusive lock escalations                 = 0
Agents currently waiting on locks          = 1
Lock Timeouts                              = 0
Internal rollbacks due to deadlock         = 0
Number of MDC table blocks pending cleanup = 0
    Memory Pool Type                           = Lock Manager Heap

第一步：

$ db2pd -db sample -locks showlocks wait

Database Partition 0 -- Database SAMPLE -- Active -- Up 9 days 15:28:01

Locks:
Address            TranHdl    Lockname                   Type       Mode Sts Owner      Dur HoldCount  Att  ReleaseFlg
0x0770000030352600 7          00030005000000000280000652 Row        .NS  W   2          1   0          0x00 0x00000001  TbspaceID 3
    TableID 5      PartitionID 0 Page 640 Slot 6
0x0770000030351940 2          00030005000000000280000652 Row        ..X  G   2          1   0          0x08 0x40000000  TbspaceID 3
    TableID 5      PartitionID 0 Page 640 Slot 6

 

 

由第一步輸出中的TranHdl對應到應用的AppHandl。

 

$ db2pd -db sample -transactions

Database Partition 0 -- Database SAMPLE -- Active -- Up 9 days 15:33:01

Transactions:
Address            AppHandl [nod-index] TranHdl    Locks      State   Tflag      Tflag2     Firstlsn       Lastlsn        LogSpace
      SpaceReserved   TID            AxRegCnt   GXID
0x07700000302A1F80 3699     [000-03699] 2          3          WRITE   0x00000000 0x00000000 0x0000032CBCF4 0x0000032CBCF4 110
      163             0x000000005E12 1          0
0x07700000302A2F00 3700     [000-03700] 3          0          READ    0x00000000 0x00000000 0x000000000000 0x000000000000 0
      0               0x00000000525D 1          0
0x07700000302A3E80 3701     [000-03701] 4          0          READ    0x00000000 0x00000000 0x000000000000 0x000000000000 0
      0               0x000000005E19 1          0
0x07700000302A4E00 3702     [000-03702] 5          0          READ    0x00000000 0x00000000 0x000000000000 0x000000000000 0
      0               0x00000000525F 1          0
0x07700000302A6D00 3704     [000-03704] 7          4          READ    0x00000000 0x00000000 0x000000000000 0x000000000000 0
      0               0x000000005DFF 1          0
0x07700000302A7C80 3835     [000-03835] 8          0          READ    0x00000000 0x00000000 0x000000000000 0x000000000000 0
      0               0x000000005E14 1          0

 

 

 

ID of agent holding lock                 = 3699   --引起3704鎖等待的agentid
  Application ID holding lock              = *LOCAL.db2inst1.090628013214
  Lock name                                = 0x00030005000000000280000652
  Lock attributes                          = 0x00000000
  Release flags                            = 0x00000001
  Lock object type                         = Row
  Lock mode                                = Exclusive Lock (X)
  Lock mode requested                      = Next Key Share (NS)
  Name of tablespace holding lock          = IBMDB2SAMPLEREL
  Schema of table holding lock             = DB2INST1
  Name of table holding lock               = DEADTABLE
  Data Partition Id of table holding lock  = 0
  Lock wait start timestamp                = 07/08/2009 01:49:56.209476

第四步：

定位引起鎖等待的sql語句

 

$db2 get snapshot for application agentid 3699

 

其中有

Dynamic SQL statement text:
insert into deadtable values(1)