SQL Server扩展事件（Extended Events）-- 使用system_health默认跟踪会话监控死锁自SQL Server 2008以后，提供了扩展事件（Extended Events）来跟踪系统分析定位问题。默认的system_health会话一直在运行，可以帮助你更快的定位问题。运行如下脚本可以看

SQL Server扩展事件（Extended Events）-- 使用system_health默认跟踪会话监控死锁

自SQL Server 2008以后，提供了扩展事件（Extended Events）来跟踪系统分析定位问题。默认的system_health会话一直在运行，可以帮助你更快的定位问题。

运行如下脚本可以看到system_health扩展事件会话：

SELECT * FROM sys.dm_xe_sessions

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即便是你没有启动任何扩展事件会话，这个查询也会返回一行system_health会话。

SQL Server 2012版本之前，并不提供管理扩展事件会话的图形界面，你可以从这里下载SQL Server 2008 Extended Events SSMS Addin插件：http://extendedeventmanager.codeplex.com/

安装好后，可以按如图方式找到扩展事件管理界面：

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而在SQL Server 2012版本中，则通过如图方式可以找到该界面：

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我们右键点击“system_health”，生成脚本，我们可以看到该会话的内容如下（SQL Server 2012版本）：

CREATE EVENT SESSION [system_health] ON SERVER
ADD EVENT sqlclr.clr_allocation_failure(
ACTION(package0.callstack,sqlserver.session_id)),
ADD EVENT sqlclr.clr_virtual_alloc_failure(
ACTION(package0.callstack,sqlserver.session_id)),
ADD EVENT sqlos.memory_broker_ring_buffer_recorded,
ADD EVENT sqlos.memory_node_oom_ring_buffer_recorded(
ACTION(package0.callstack,sqlserver.session_id,sqlserver.sql_text,sqlserver.tsql_stack)),
ADD EVENT sqlos.scheduler_monitor_deadlock_ring_buffer_recorded,
ADD EVENT sqlos.scheduler_monitor_non_yielding_iocp_ring_buffer_recorded,
ADD EVENT sqlos.scheduler_monitor_non_yielding_ring_buffer_recorded,
ADD EVENT sqlos.scheduler_monitor_non_yielding_rm_ring_buffer_recorded,
ADD EVENT sqlos.scheduler_monitor_stalled_dispatcher_ring_buffer_recorded,
ADD EVENT sqlos.scheduler_monitor_system_health_ring_buffer_recorded,
ADD EVENT sqlos.wait_info(
ACTION(package0.callstack,sqlserver.session_id,sqlserver.sql_text)
WHERE ([duration]>(15000) AND ([wait_type]>(31) AND ([wait_type]>(47) AND [wait_type]<(54) OR [wait_type]<(38) OR [wait_type]>(63) AND [wait_type]<(70) OR [wait_type]>(96) AND [wait_type]<(100) OR [wait_type]=(107) OR [wait_type]=(113) OR [wait_type]>(174) AND [wait_type]<(179) OR [wait_type]=(186) OR [wait_type]=(207) OR [wait_type]=(269) OR [wait_type]=(283) OR [wait_type]=(284)) OR [duration]>(30000) AND [wait_type]<(22)))),
ADD EVENT sqlos.wait_info_external(
ACTION(package0.callstack,sqlserver.session_id,sqlserver.sql_text)
WHERE ([duration]>(5000) AND ([wait_type]>(365) AND [wait_type]<(372) OR [wait_type]>(372) AND [wait_type]<(377) OR [wait_type]>(377) AND [wait_type]<(383) OR [wait_type]>(420) AND [wait_type]<(424) OR [wait_type]>(426) AND [wait_type]<(432) OR [wait_type]>(432) AND [wait_type]<(435) OR [duration]>(45000) AND ([wait_type]>(382) AND [wait_type]<(386) OR [wait_type]>(423) AND [wait_type]<(427) OR [wait_type]>(434) AND [wait_type]<(437) OR [wait_type]>(442) AND [wait_type]<(451) OR [wait_type]>(451) AND [wait_type]<(473) OR [wait_type]>(484) AND [wait_type]<(499) OR [wait_type]=(365) OR [wait_type]=(372) OR [wait_type]=(377) OR [wait_type]=(387) OR [wait_type]=(432) OR [wait_type]=(502))))),
ADD EVENT sqlserver.connectivity_ring_buffer_recorded(SET collect_call_stack=(1)),
ADD EVENT sqlserver.error_reported(
ACTION(package0.callstack,sqlserver.database_id,sqlserver.session_id,sqlserver.sql_text,sqlserver.tsql_stack)
WHERE ([severity]>=(20) OR ([error_number]=(17803) OR [error_number]=(701) OR [error_number]=(802) OR [error_number]=(8645) OR [error_number]=(8651) OR [error_number]=(8657) OR [error_number]=(8902)))),
ADD EVENT sqlserver.security_error_ring_buffer_recorded(SET collect_call_stack=(1)),
ADD EVENT sqlserver.sp_server_diagnostics_component_result(SET collect_data=(1)
WHERE ([sqlserver].[is_system]=(1) AND [component]<>(4))),
ADD EVENT sqlserver.xml_deadlock_report
ADD TARGET package0.event_file(SET filename=N'system_health.xel',max_file_size=(5),max_rollover_files=(4)),
ADD TARGET package0.ring_buffer(SET max_events_limit=(5000),max_memory=(4096))
WITH (MAX_MEMORY=4096 KB,EVENT_RETENTION_MODE=ALLOW_SINGLE_EVENT_LOSS,MAX_DISPATCH_LATENCY=120 SECONDS,MAX_EVENT_SIZE=0 KB,MEMORY_PARTITION_MODE=NONE,TRACK_CAUSALITY=OFF,STARTUP_STATE=ON)
GO

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你也可以在SQL Server的安装目录：C:\Program Files\Microsoft SQL Server\MSSQL11.\MSSQL\Install

下找到脚本u_tables.sql文件。

从定义可以看到，会话的输出包含callstack、sessionID、TSQL和TSQL Call Stack

且当安全等级大于20或者错误号为17803等。它们与内存压力相关、Non-yielding scheduler问题、死锁和一些类型的等待。

会话输出被捕获到遵从FIFO规则的ring_buffer中，ring_buffer是一个内存使用者，它以二进制格式存储捕获数据。当事件会话启用的时候，数据即可被捕获。当停止会话的时候，分配给ring_buffer的内存被释放，且数据消失。注意：对于SQL Server 2012之前，system_health的目标只有ring_buffer，从SQL Server 2012开始，增加了event_file的输出。

你可以通过关联sys.dm_xe_session_targets和sys.dm_xe_sessions视图来查看ring_buffer或event_file的内容，并转换二进制数据为XML格式。

SELECT name, target_name, CAST(target_data AS XML) target_data
FROM sys.dm_xe_sessions s
INNER JOIN sys.dm_xe_session_targets t
ON s.address = t.event_session_address
WHERE s.name = 'system_health'
GO

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注意：event_file的输出是文件的存储路径，而ring_buffer的输出是捕获到的数据。

在ring_buffer中，每一个事件元素都有一个数据子集和一个动作子集。这些动作是在会话的定义中。数据元素包含了每个事件的数据类型列的所有值。这些列可通过sys.dm_xe_object_columns视图输出。让我们解析XML格式以表格格式查看内容。因为每个事件返回数据列的不同集合。下面给一个error_reported事件的例子。

DECLARE @x XML =
(SELECT CAST(target_data AS XML)
FROM sys.dm_xe_sessions s
INNER JOIN sys.dm_xe_session_targets t
ON s.address = t.event_session_address
WHERE s.name = 'system_health' and t.target_name = 'ring_buffer')
SELECT t.e.value('@name', 'varchar(50)') AS EventName
,t.e.value('@timestamp', 'datetime') AS DateAndTime
,t.e.value('(data[@name="error"]/value)[1]', 'int') AS ErrNo
,t.e.value('(data[@name="severity"]/value)[1]', 'int') AS Severity
,t.e.value('(data[@name="message"]/value)[1]', 'varchar(max)') AS ErrMsg
,t.e.value('(action[@name="sql_text"]/value)[1]', 'varchar(max)') AS sql_text
FROM @x.nodes('//RingBufferTarget/event') AS t(e)
WHERE t.e.value('@name', 'varchar(50)') = 'error_reported'

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对于system_health最有帮助的用途之一是跟踪死锁。对于目标ringbuffer，存储多少数据依赖于被监控机器上的该目标的容量，以及产生最大数量的设置相关，这些将在每个会话的定义中。你可以在system_health会话的输出中找到过去的死锁记录。

所有查询都会在system_health输出中，可以通过运行下面的代码获得一个死锁报表。

-- SQL Server 2008 R2
WITH SystemHealth
AS (
SELECT CAST(target_data as xml) AS TargetData
FROM sys.dm_xe_session_targets st
JOIN sys.dm_xe_sessions s
ON s.address = st.event_session_address
WHERE name = 'system_health'
AND st.target_name = 'ring_buffer')
SELECT XEventData.XEvent.value('@timestamp','datetime')as Creation_Date,CAST(XEventData.XEvent.value('(data/value)[1]','VARCHAR(MAX)') AS XML) AS DeadLockGraph
FROM SystemHealth
CROSS APPLY TargetData.nodes('//RingBufferTarget/event') AS XEventData (XEvent)
WHERE XEventData.XEvent.value('@name','varchar(4000)') = 'xml_deadlock_report'
ORDER BY Creation_Date DESC

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<deadlock>
<victim-list>
<victimProcess id="process14df44748" />
</victim-list>
<process-list>
<process id="process14df44748" taskpriority="0" logused="0" waitresource="KEY: 5:72057594297647104 (25d29b0b697a)" waittime="2417" ownerId="12672266142" transactionname="FETCH CURSOR" lasttranstarted="2014-12-10T13:21:31.360" XDES="0x8005b920" lockMode="S" schedulerid="7" kpid="3700" status="suspended" spid="130" sbid="0" ecid="0" priority="0" trancount="0" lastbatchstarted="2014-12-10T13:21:00.133" lastbatchcompleted="2014-12-10T13:21:00.133" clientapp="SQLAgent - TSQL JobStep (Job 0xD7D593D56AA41A45B878CDD0BE6EEC79 : Step 1)" hostname="SZSQL01" hostpid="2604" loginname="WMS" isolationlevel="read committed (2)" xactid="12672266142" currentdb="5" lockTimeout="4294967295" clientoption1="673316896" clientoption2="128056">
<executionStack>
<frame procname="" line="128" stmtstart="7494" stmtend="7632" sqlhandle="0x0300050099c38b5d87698c00659f00000100000000000000" />
<frame procname="" line="240" stmtstart="16044" stmtend="16204" sqlhandle="0x0300050063e39f5eec9c8501a19f00000100000000000000" />
<frame procname="" line="457" stmtstart="35402" stmtend="35694" sqlhandle="0x03000500ab05e430a8c2550148a200000100000000000000" />
<frame procname="" line="542" stmtstart="37436" stmtend="38776" sqlhandle="0x03000500622bc26d4be30101bf9f00000100000000000000" />
<frame procname="" line="80" stmtstart="5236" stmtend="5464" sqlhandle="0x030005009d864d5cf36f1401d5a300000100000000000000" />
<frame procname="" line="2" stmtstart="4" sqlhandle="0x0100050082ce6918f0cd5f69020000000000000000000000" />
</executionStack>
<inputbuf>
Exec SPSO_UrgentOrder_Allocation 'C','SYSTEM','' </inputbuf>
</process>
<process id="process9062508" taskpriority="0" logused="1172" waitresource="KEY: 5:72057594298040320 (a0d5874b4f9e)" waittime="2417" ownerId="12672266145" transactionname="DELETE" lasttranstarted="2014-12-10T13:21:31.360" XDES="0xc1a633c0" lockMode="X" schedulerid="10" kpid="6728" status="suspended" spid="74" sbid="0" ecid="0" priority="0" trancount="2" lastbatchstarted="2014-12-10T13:21:27.530" lastbatchcompleted="2014-12-10T13:21:27.527" clientapp="jTDS" hostname="UNKNOWN" hostpid="123" loginname="WMS" isolationlevel="read committed (2)" xactid="12672266145" currentdb="5" lockTimeout="4294967295" clientoption1="673316896" clientoption2="128056">
<executionStack>
<frame procname="" line="123" stmtstart="7034" stmtend="7406" sqlhandle="0x0300050099c38b5d87698c00659f00000100000000000000" />
<frame procname="" line="240" stmtstart="16044" stmtend="16204" sqlhandle="0x0300050063e39f5eec9c8501a19f00000100000000000000" />
<frame procname="" line="457" stmtstart="35402" stmtend="35694" sqlhandle="0x03000500ab05e430a8c2550148a200000100000000000000" />
<frame procname="" line="542" stmtstart="37436" stmtend="38776" sqlhandle="0x03000500622bc26d4be30101bf9f00000100000000000000" />
</executionStack>
<inputbuf>
Proc [Database Id = 5 Object Id = 1841441634] </inputbuf>
</process>
</process-list>
<resource-list>
<keylock hobtid="72057594297647104" dbid="5" objectname="" indexname="" id="lock486c0f580" mode="X" associatedObjectId="72057594297647104">
<owner-list>
<owner id="process9062508" mode="X" />
</owner-list>
<waiter-list>
<waiter id="process14df44748" mode="S" requestType="wait" />
</waiter-list>
</keylock>
<keylock hobtid="72057594298040320" dbid="5" objectname="" indexname="" id="lock5520aee00" mode="S" associatedObjectId="72057594298040320">
<owner-list>
<owner id="process14df44748" mode="S" />
</owner-list>
<waiter-list>
<waiter id="process9062508" mode="X" requestType="wait" />
</waiter-list>
</keylock>
</resource-list>
</deadlock>

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-- SQL Server 2012
WITH SystemHealth
AS (
SELECT CAST(target_data as xml) AS TargetData
FROM sys.dm_xe_session_targets st
JOIN sys.dm_xe_sessions s
ON s.address = st.event_session_address
WHERE name = 'system_health'
AND st.target_name = 'ring_buffer')
SELECT XEventData.XEvent.value('@timestamp','datetime')as Creation_Date, XEventData.XEvent.query('(data/value/deadlock)[1]') AS DeadLockGraph
FROM SystemHealth
CROSS APPLY TargetData.nodes('//RingBufferTarget/event') AS XEventData (XEvent)
WHERE XEventData.XEvent.value('@name','varchar(4000)') = 'xml_deadlock_report'
ORDER BY Creation_Date DESC

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<deadlock>
<victim-list>
<victimProcess id="process2b17a4558" />
</victim-list>
<process-list>
<process id="process2b17a4558" taskpriority="0" logused="672" waitresource="KEY: 5:72057594043826176 (286fc18d83ea)" waittime="6162" ownerId="7084361" transactionname="user_transaction" lasttranstarted="2015-01-06T10:48:42.090" XDES="0x2b6c1d6a8" lockMode="S" schedulerid="2" kpid="1624" status="suspended" spid="63" sbid="0" ecid="0" priority="0" trancount="1" lastbatchstarted="2015-01-06T10:48:42.090" lastbatchcompleted="2015-01-06T10:45:25.407" lastattention="1900-01-01T00:00:00.407" clientapp="Microsoft SQL Server Management Studio - Query" hostname="WIN-LLPKR5BUV6S" hostpid="4712" loginname="WIN-LLPKR5BUV6S\Administrator" isolationlevel="read committed (2)" xactid="7084361" currentdb="5" lockTimeout="4294967295" clientoption1="671090784" clientoption2="390200">
<executionStack>
<frame procname="adhoc" line="6" stmtstart="24" sqlhandle="0x020000002d83010497edc81695b0146b2f0000b7b2d28d190000000000000000000000000000000000000000">
SELECT * FROM [Person].[Address] WHERE [AddressID]=@1 </frame>
<frame procname="adhoc" line="6" stmtstart="298" sqlhandle="0x02000000ab47741a8c9b1c9d67d523f9675a2ccfdcfc4fd10000000000000000000000000000000000000000">
SELECT * FROM Person.Address WHERE AddressID = 20 </frame>
</executionStack>
<inputbuf>
--Window 2
USE AdventureWorks2012
BEGIN TRAN
UPDATE Person.Address SET AddressLine1 = 'New address' WHERE AddressID = 25
WAITFOR DELAY '0:0:30'
SELECT * FROM Person.Address WHERE AddressID = 20 </inputbuf>
</process>
<process id="process2b986d868" taskpriority="0" logused="6288" waitresource="KEY: 5:72057594043826176 (b81181109ebc)" waittime="4852" ownerId="7078917" transactionname="user_transaction" lasttranstarted="2015-01-06T10:35:45.447" XDES="0x2bd04f078" lockMode="S" schedulerid="2" kpid="3064" status="suspended" spid="61" sbid="0" ecid="0" priority="0" trancount="3" lastbatchstarted="2015-01-06T10:48:43.400" lastbatchcompleted="2015-01-06T10:45:25.407" lastattention="1900-01-01T00:00:00.407" clientapp="Microsoft SQL Server Management Studio - Query" hostname="WIN-LLPKR5BUV6S" hostpid="4712" loginname="WIN-LLPKR5BUV6S\Administrator" isolationlevel="read committed (2)" xactid="7078917" currentdb="5" lockTimeout="4294967295" clientoption1="671090784" clientoption2="390200">
<executionStack>
<frame procname="adhoc" line="6" stmtstart="24" sqlhandle="0x020000002d83010497edc81695b0146b2f0000b7b2d28d190000000000000000000000000000000000000000">
SELECT * FROM [Person].[Address] WHERE [AddressID]=@1 </frame>
<frame procname="adhoc" line="6" stmtstart="296" sqlhandle="0x02000000ea66c804b69860bd70b44e12bc27b94558e83d010000000000000000000000000000000000000000">
SELECT * FROM Person.Address WHERE AddressID = 25 </frame>
</executionStack>
<inputbuf>
--Window1
USE AdventureWorks2012
BEGIN TRAN
UPDATE Person.Address SET AddressLine1 = 'New address' WHERE AddressID = 20
WAITFOR DELAY '0:0:30'
SELECT * FROM Person.Address WHERE AddressID = 25
</inputbuf>
</process>
</process-list>
<resource-list>
<keylock hobtid="72057594043826176" dbid="5" objectname="AdventureWorks2012.Person.Address" indexname="1" id="lock2ac70b500" mode="X" associatedObjectId="72057594043826176">
<owner-list>
<owner id="process2b986d868" mode="X" />
</owner-list>
<waiter-list>
<waiter id="process2b17a4558" mode="S" requestType="wait" />
</waiter-list>
</keylock>
<keylock hobtid="72057594043826176" dbid="5" objectname="AdventureWorks2012.Person.Address" indexname="1" id="lock2b992b200" mode="X" associatedObjectId="72057594043826176">
<owner-list>
<owner id="process2b17a4558" mode="X" />
</owner-list>
<waiter-list>
<waiter id="process2b986d868" mode="S" requestType="wait" />
</waiter-list>
</keylock>
</resource-list>
</deadlock>

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查看process-list的inputbuf子元素，可以看到导致死锁的代码片段，process-list显示所有死锁参与者的进程ID。process元素包含spid、数据库id、登录名、隔离级别、客户端应用程序名。Resource-list元素包含在死锁中的资源。查看owner-list和waiter-list元素可以看到这两个进程如何互相阻塞。

尝试将该XML的输出保存为XDL文档，用SSMS打开异常。目前有两个选择可以以图形方式打开死锁图表：SQL Sentry Plan Explorer Pro 和 SQL Server 2012 Management Studio，详见：https://www.sqlskills.com/blogs/jonathan/graphically-viewing-extended-events-deadlock-graphs/