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Getting the most out of WLDF Part 4: The Monitoring Dashboard

Read Part 1: "What is the WLDF?" here
Read Part 2: "Watches" here
Read Part 3: "Notifications" here

 

 

This is going to be a fairly short post, because there isn’ta huge amount to go into that we haven’t already covered!

 

 

The WLDF monitoring dashboard gives a visual representationof available metrics from WebLogic MBeans. If you know how to drag-and-drop,then you have all the technical ability you need.

 

In this blog post, I will refer to an annotated image with colourcoded headings so you can see which part I’m talking about.

 

 

 

How do I find it?

 

 

On the console home page, look on the bottom right-handcorner for a link called “Monitoring Dashboard” and you’ll find yourselflooking at something similar to the screen below (except without all the chartdata!)

The annotations are explained below

Creating and populating aview

 

We start at the top left with the “View List” tab and the “MetricBrowser” tab. The chances are, when you first go to the Monitoring Dashboard,the View List will be shown. Each view can have many charts on it; the exampleabove is a view called “Session”with a single chart called “Sessions”. Examples of views with more charts canbe seen in the Built-in Views. To keep my example simple, I stayed with onechart in a fresh view.

 

Once your view and charts have been created, use the greenplay button to start recording metric values for the selected view.You will need to press the play button on each view you want to record metricson, and use the red stop button to stop recording for the selected view. Theoctagonal red button will stop all collections.

 

Adding metrics to achart

After having created a new view and added a chart, you willneed to add some metrics. Because there are so many to choose from, you firstneed to narrow down the ones you’re concerned about.
If you’ve no idea how to know which metrics are available, Icovered that in part2 of this series on watches. In that blog post, I found the open sessions countfor a web application using the following string: (${com.bea:Name=AdminServer, Type=WebAppComponentRuntime//OpenSessionsCurrentCount}>= 1)
To find the same MBean in the Metric Browser, we need tomake sure we’ve selected the right server first, as shown in the “com.bea:Name”segment of the string above. The “Type” corresponds to the “Types” section inthe metric browser, so I’ve selected “WebAppComponent”.
That then gives me a list of instances, so I pick_/clusterjsp, since that’s the webapp I’m interested in, and then scroll to theOpenSessionsCurrentCount metric which I can drag and drop on the empty chart.

 

Modifying the chart

 Once you have some metrics added to the chart, and you’veclicked the green play button so that metrics are captured, you might find thatyou actually don’t want a line chart at all! Perhaps your data is much moresuited to a bar chart.
To change the chart type, click the dropdown arrow next tothe pencil icon. Clicking the pencil icon will allow you to change the name ofthe chart.

Adjusting the chart

Using the same dropdown arrow, you can choose to zoom in orout on the chart, or show earlier or later values.
Another, more intuitive way is to use the “mini-map” chartin the bottom right corner. The same zoon in/out and earlier/later arrows arethere, but the miniaturised view of the chart is interactive. Click and drag tohighlight peaks and troughs and the chart will update to show you that periodof time in more detail.

 

Interpreting the data

Finally, it’s important to be able to interpret the data. Onmy example chart, I’ve circled in blue where an event clearly happens. Hoveringover any of the data points will tell you exactly what the value is, as I’veshown with the HeapFreePercent metric (the red triangles)
We can see that there is a garbage collection event therebecause the red triangle data points which represent how much of the total heapis free gets down below 10% and then leaps up to about 33%.
What we can also see is that it was a young heap collection, thanks to the two half-moon shaped datapoints, in dark red and blue. The dark red line, which represents the total numberof young heap collections since the server started, jumps up by 1; whereas thedark blue line, which represents old heap collections, stays at 0.
That’s really all there is to it! The key to making thedashboard really useful is spending the time to create meaningful charts, likea chart to monitor garbage collection and a chart to monitor a specific app.
There is a lot of power in being able to visualise data inthis way. Consider the scenario: you set up a view for 10 of your criticalapps. 1 – 5 might be on server A and 6-10 might be on server B. If you can seethat all of apps 1 – 5 start to respond very slowly, you can look in a view ofserver A to see if there are any stop-the-world pauses during that time, or ifthe heap is running low on memory.