What am I looking at here?
Shown above is a set of blocked process report. But it’s being displayed using SQL Server’s Deadlock Graph Control. Here’s a detail of the graph:
I’m totally wearing my hacker hat with this. Microsoft built the deadlock graph control to display deadlock graphs generated by Microsoft’s tools. What I’ve done is to take a set of blocked process reports and reformat them to look like a deadlock graph. You can tell that it’s not a deadlock because the graph is a tree, with no cycles.
See that process with the X through it. Normally it indicates a deadlock victim. But in this case, I’ve repurposed the X to indicate the lead blocker (i.e. the stalled car in the traffic jam of blocked SQL Servers).
The graph is useful because it can tell a story graphically that would otherwise take maybe 100 times longer to understand by reading the xml reports directly.
A few years ago when I installed SQL Server 2005 for the first time, I played around with SQL Server profiler and traces in general and had one of those moments that made me say “nifty!” I was looking at a deadlock graph displayed graphically.
Not much later after that, I noticed that blocked process reports contain information very similar to deadlock graphs. It wasn’t much of a leap to think that with a little creative reformatting, I could make the deadlock graph control do something else useful with blocked process reports.
So here’s what you do:
- Find a trace that contains blocked processes reports. If it’s not already, save it as a table called blocked. The script below assumes that a table called blocked has already been created. (Alternatively, create an synonym called blocked that refers to a table)
- Copy the script below and run it in Management Studio.
- Click the blocking chain xml of interest to you.
- Save the xml file as an xdl file.
- Close and reopen the file in Management Studio.
The man behind the curtains.
So here’s the script I talked about. It’s also an example of me flexing my XML muscles.
Update Mar. 29, 2010 Due to the size of the script and some other formatting issues, I’m providing the script as a link rather than something to copy and paste. Download the script here.