Capturing Deadlocks with Extended Events

I’ve been noticing a lot of deadlocks on my server. What’s the best way to track down the queries so I can fix the problem?

There are a few different ways that you can capture deadlock information. You can setup a trace flag (1222) to write the deadlock information to the error log, setup a Profiler trace to capture the deadlock graph, or setup an Extended Event to capture all sorts of information.

I’m going to focus on setting up an Extended Event in this post since MS continues to say Profiler will not be released in future versions. Extended Events are the future so why not start using them now?

In SSMS, drill down to Management, Extended Events. Right click on Sessions and click New Session Wizard:

Deadlocks with Extended Events 1

Click next on the Introduction screen and give the Session a name. I’m going to name this session Deadlocks:

Deadlocks with Extended Events 2

Click next. On the Choose Template screen you can choose a predefined template (like Profiler) or you can create your own events by choosing “Do not use a template”. For this post, let’s create our own:

Deadlocks with Extended Events 3

Click next and you’ll see hundreds of events (like Profiler). We only want to capture deadlock data so let’s scroll down to the very bottom and choose xml_deadlock_report. Click on the event and click the right arrow to move it into the Selected Events box:

Deadlocks with Extended Events 4

You can choose other events if needed, but for the simplicity of this post I’m just going to use this one. Click next. The Capture Global Fields page allows us to select what fields we want to capture. These are unique to each event selected. For this example, I’ll choose the following fields:

  • Callstack
  • Client_app_name
  • Client_hostname
  • Database_id
  • Database_name
  • Plan_handle
  • Process_id
  • Sql_text
  • Transaction_id
  • Transaction_sequence

Deadlocks with Extended Events 5

Click next. On this page you can apply filters if needed. I’ll setup a filter so that I only capture data from the RollTide database. There are hundreds of different filters that can be configured so that you don’t pull back data that is not needed:

Deadlocks with Extended Events 6

Click next to the Session Data Storage page. This page allows you to save data to a file or work with only the most recent data. I don’t want to keep thousands upon thousands of events so I’ll choose “Work with only the most recent data”

Deadlocks with Extended Events 7

The next page summarizes all the options we have selected. You can also script this session if you need to create it on other servers or save it for later. Click Finish to create the new session.

The last page allows you to start the session immediately and watch live data. For this post, I’ll choose both:

Deadlocks with Extended Events 8

You should see the new session under Extended Events and the Live Data tab should appear:

Deadlocks with Extended Events 9

Deadlocks with Extended Events 10

Once a deadlock occurs it should show the deadlock in the Live Data window:

Deadlocks with Extended Events 11

This view shows all of the fields we selected including the XML report. If you click on the Deadlock tab, you’ll see the graph:

Deadlocks with Extended Events 12

You can also use this query to see detailed information including the Deadlock graph and Event XML

DATEADD(mi, DATEDIFF(mi, GETUTCDATE(), CURRENT_TIMESTAMP), DeadlockEventXML.value('(event/@timestamp)[1]', 'datetime2')) AS [EventTime],
DeadlockEventXML.value('(//process[@id[//victim-list/victimProcess[1]/@id]]/@hostname)[1]', 'nvarchar(max)') AS HostName,
DeadlockEventXML.value('(//process[@id[//victim-list/victimProcess[1]/@id]]/@clientapp)[1]', 'nvarchar(max)') AS ClientApp,
DB_NAME(DeadlockEventXML.value('(//process[@id[//victim-list/victimProcess[1]/@id]]/@currentdb)[1]', 'nvarchar(max)')) AS [DatabaseName],
DeadlockEventXML.value('(//process[@id[//victim-list/victimProcess[1]/@id]]/@transactionname)[1]', 'nvarchar(max)') AS VictimTransactionName,
DeadlockEventXML.value('(//process[@id[//victim-list/victimProcess[1]/@id]]/@isolationlevel)[1]', 'nvarchar(max)') AS IsolationLevel,
DeadlockEventXML.query('(event/data[@name="xml_report"]/value/deadlock)[1]') AS DeadLockGraph,
XEvent.query('.') AS DeadlockEventXML,
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 = 'Deadlocks' AND
st.target_name = 'ring_buffer'
) AS Data
CROSS APPLY TargetData.nodes('RingBufferTarget/event[@name="xml_deadlock_report"]') AS XEventData(XEvent)
) AS DeadlockInfo 

Managing SQL Server Extended Events in Management Studio

SQL Server 2012 introduces a GUI in SQL Server Management Studio to create and manage extended events. Prior to the SQL Server 2012 integration, Extended Events could only be created using T-SQL. In this tip, I’ll show you step by step process on how to create a simple Extended Event in SQL Server 2012 using the new GUI in SQL Server Management Studio.

Creating an Extended Event has never been easier with SQL Server 2012. Open SSMS, and drilldown to Management, Extended Events, Sessions as shown in the image below.  By default, you should see an AlwaysOn_health and a system_health session already created. You will notice the AlwaysOn_health session is disabled and the system_health session is running. The system_health session collects system data that you can use to help troubleshoot performance issues. For the most part, SQL Server Extended Events use very little resources.

SQL Freelancer SQL Server Extended Events Management Studio SSMS
There are two ways to create a session. Right click on the Sessions folder and you can choose New Session or New Session Wizard. In this tip, we’ll step through using the wizard.

SQL Freelancer SQL Server Extended Events Management Studio SSMS

After clicking New Session Wizard, an Introduction window will appear that will give you a brief introduction. Click the “Next” button to continue.

The next window, Set Session Properties, is where you can specify the session name and whether or not you want the session to start on server start-up. In this tip, I’ll name the session DB Monitor and choose to start the event session at server start-up. Click the “Next” button to continue.

SQL Freelancer SQL Server Extended Events Management Studio SSMS
The next screen will allow us to choose a preconfigured template or create our own. If you’ve ever used SQL Server Profiler’s built in template, these function the same way. In this tip, we’ll create our own. Choose the “Do not use a template” option and click the “Next” button to continue.

SQL Freelancer SQL Server Extended Events Management Studio SSMS
The “Select Events To Capture” window is an important one. This is where we select the events we want to capture. For this example, I want to monitor when my DB goes offline and when it becomes available, so I’ll choose the events that relate to this: database_attached, database_created, database_detached, database_started, and database_stopped. Once you select the events from the “Event library” (on the left), click the right arrow to move them to the “Selected events” (on the right). Click the “Next” button to continue.

SQL Freelancer SQL Server Extended Events Management Studio SSMS

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