问题引入

在前面三篇文章，我们分别谈到了使用DBCC命令捕获死锁；使用Profiler界面跟踪Deadlock Graph事件捕获死锁和使用脚本自动部署Profiler Trace捕获死锁。这篇文章介绍一个非常有意思的捕获死锁的方法：使用SQL Server Service Broker Event Notification来捕获死锁。

Service Broker Event Notification

Service Broker Event Notification即使用SQL Server引擎内置的异步消息通讯机制加上SQL Server的事件通知机制来捕获死锁信息，这个方法非常简单，对SQL Server数据库本身影响非常小。一个简单的模型是将捕获到的死锁xml信息存放在队里中，然后分析队列，重现详细的死锁场景。代码如下：

USE [master] GO IF DB_ID('DeadlockCapture') IS NULL CREATE DATABASE [DeadlockCapture]; GO ALTER DATABASE [DeadlockCapture] SET ENABLE_BROKER GO USE [DeadlockCapture] GO --Create Event Notification Queue to save Deadlock Info CREATE QUEUE QueueDeadLockNotification ; --Create Event Notification Services CREATE SERVICE ServiceDeadlockNotification ON QUEUE QueueDeadLockNotification ([http://schemas.microsoft.com/SQL/Notifications/PostEventNotification]); GO -- Create route for the DeadlockNotificationSvc CREATE ROUTE RouteDeadLockNotification WITH SERVICE_NAME = 'ServiceDeadlockNotification', ADDRESS = 'LOCAL'; GO -- Create Event Notification for the deadlock_graph event. CREATE EVENT NOTIFICATION DeadLockNotificationEvent ON SERVER FOR DEADLOCK_GRAPH TO SERVICE 'ServiceDeadlockNotification', 'current database' GO

死锁测试的方法和过程参见文章RDS SQL Server死锁（Deadlock）系列之一使用DBCC捕获死锁中死锁测试部分，在此不再累述。

分析死锁

当死锁发生后，死锁信息会被异步的记录到Service Broker队列中。

USE [DeadlockCapture] GO select CAST(message_body as xml),* from QueueDeadLockNotification

查询结果展示如下：

接下来的工作就是分析队里中的死锁信息，分析方法和前面几篇文章的分析方法大同小异，只是在公用表达式的初始化部分稍有差异。方法如下：

use master go ;WITH DATA AS ( -- Analysis deadlock when saving into Service Broker Event Notification select RowNumber = row_number() OVER (ORDER BY queuing_order) ,DeadlockGraph = CAST(message_body as xml).query('./EVENT_INSTANCE/TextData/deadlock-list') from [DeadlockCapture].[dbo].[QueueDeadLockNotification] WITH(NOLOCK) ) , deadlock AS ( SELECT RowNumber ,OwnerID = T.C.value('@id', 'varchar(50)') ,SPid = T.C.value('(./@spid)[1]','int') ,status = T.C.value('(./@status)[1]','varchar(10)') ,Victim = case when T.C.value('@id', 'varchar(50)') = T.C.value('./../../@victim','varchar(50)') then 1 else 0 end ,LockMode = T.C.value('@lockMode', 'varchar(20)') ,DeadlockGraph ,Inputbuf = T.C.value('(./inputbuf/text())[1]','varchar(max)') ,Code = T.C.value('(./executionStack/frame/text())[1]','VARCHAR(max)') ,SPName = T.C.value('(./executionStack/frame/@procname)[1]','sysname') ,Hostname = T.C.value('(./@hostname)[1]','sysname') ,Clientapp = T.C.value('(./@clientapp)[1]','varchar(max)') ,LoginName = T.C.value('@loginname', 'varchar(20)') ,Action = T.C.value('(./@transactionname)[1]','varchar(max)') ,TransactionTime = T.C.value('@lasttranstarted', 'datetime') FROM DATA AS A CROSS APPLY DeadlockGraph.nodes('deadlock-list/deadlock/process-list/process') AS T(C) ) , keylock AS ( SELECT OwnerID = T.C.value('./owner[1]/@id', 'varchar(50)') ,KeylockObject = T.C.value('./../@objectname', 'varchar(200)') ,Indexname = T.C.value('./../@indexname', 'varchar(200)') ,IndexLockMode = T.C.value('./../@mode', 'varchar(20)') FROM DATA AS A CROSS APPLY DeadlockGraph.nodes('deadlock-list/deadlock/resource-list/keylock/owner-list') AS T(C) ) SELECT A.SPid ,is_Vitim = A.Victim ,A.SPName ,A.Code ,A.LockMode ,B.Indexname ,B.KeylockObject ,B.IndexLockMode ,A.Inputbuf ,A.Hostname ,A.LoginName ,A.Clientapp ,A.Action ,status ,A.TransactionTime FROM deadlock AS A LEFT JOIN keylock AS B ON A.OwnerID = B.OwnerID ORDER BY A.RowNumber,A.Victim

展示结果如下图所示：

最后总结

使用Service Broker Event Notification来捕获死锁信息，是一个比较新颖的选择，由于采用异步消息通讯的方式，对SQL Server影响非常小。个人建议使用该方法来捕获、分析死锁。

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