如何监视DB2中的死锁

Question

我正在关注此链接并尝试模拟死锁问题：

http://www.dba-db2.com/2012/06/how-to-monitor-a-deadlock-in-db2.html

我可以看到我的命令运行成功。

之后我通过DbVisualiser工具模拟死锁错误。但是，我没有看到任何文件生成到路径。

有人能指出错误给我吗？

而且，我尝试回读那些旧的0000000.evt文件，它向我显示如下内容：

                            EVENT LOG HEADER
  Event Monitor name: DB2DETAILDEADLOCK
  Server Product ID: SQL10059
  Version of event monitor data: 12
  Byte order: BIG ENDIAN
  Number of nodes in db2 instance: 1
  Codepage of database: 1208
  Territory code of database: 1
  Server instance name: db2inst1
--------------------------------------------------------------------------

--------------------------------------------------------------------------
  Database Name: MYDB   
  Database Path: /db2home/db2inst1/NODE0000/SQL00003/MEMBER0000/
  First connection timestamp: 01/29/2018 10:00:17.694784
  Event Monitor Start time:   01/29/2018 10:00:18.951331
--------------------------------------------------------------------------

--------------------------------------------------------------------------
  Database Name: MYDB   
  Database Path: /db2home/db2inst1/NODE0000/SQL00003/MEMBER0000/
  First connection timestamp: 01/29/2018 10:12:54.382936
  Event Monitor Start time:   01/29/2018 10:12:54.697223
--------------------------------------------------------------------------

这意味着没有死锁？

Answer 1

对我来说正常工作（linux，Db2 v11.1）。以下是一些带注释的命令行。您需要为每个命令拥有合适的授权/特权。我正在使用实例所有者帐户。

首先禁用默认的db2detaildeadlock监视器，然后创建自己的监视器：

$ db2 "set event monitor db2detaildeadlock state=0"      
DB20000I  The SQL command completed successfully.
$ 
$ db2 "create event monitor dlmon for deadlocks write to file '/tmp'"
DB20000I  The SQL command completed successfully.
$
$ db2 "set event monitor dlmon state=1"
DB20000I  The SQL command completed successfully.
$

生成死锁，确保您看到带有原因码2的SQLCODE -911。如果您没有看到原因码2，那么您没有任何死锁但是您可能有超时并且超时不会记录在死锁监视器中。

在这里，我向死亡的受害者展示了回滚的通知，你可以看到正确的原因代码：

$ db2 +c "select * from db2inst1.dlk where a=4 with rr"
SQL0911N  The current transaction has been rolled back because of a deadlock 
or timeout.  Reason code "2".  SQLSTATE=40001

使用db2evmon调查监视器输出并查看生成的文件

$ db2evmon -db mydb -evm dlmon > /tmp/db2evmon.dlmon.1

Reading /tmp/00000000.evt ...

$ view /tmp/db2evmon.dlmon.1
...<snip>
...
3) Deadlock Event ...
  Deadlock ID:   2
  Number of applications deadlocked: 2
  Deadlock detection time: 01/03/2018 09:06:39.019854
  Rolled back Appl participant no: 2
  Rolled back Appl Id: *LOCAL.db2inst1.180301090546
  Rolled back Appl seq number: 00001
  Rolled back Appl handle: 11872

...<snip>