Explore the Application Dashboard
Let’s look more closely at your running application. While the Management Dashboard is designed for administrators, the Application Dashboard is more useful for developers. You can even set up your own dashboard by saving a set of cards in your preferred arrangement with a query to focus on just the jobs that are of interest to you.
- In the title bar, click Management Dashboard > Open Dashboard > Application Dashboard.
Some of the cards are equivalent to similar ones in the Management Dashboard:
- Metrics Scatter Chart: shows the same information as PEs.
- Metrics Bar Chart: by default this shows the same information as Resources.
In addition, there are other cards with useful information:
- Summary card: shows at a glance the health or exception status of jobs, operators, streams, and congestion (and consistent regions, which this lab does not explore).
- Streams Tree: this is similar to the Streams Explorer in Studio.
- A Streams Graph: this is similar to the Instance Graph in Studio; if you have more than one job running, you must expand twisties to see their graphs.
- Flow Rate Chart: shows the tuple submission rates of all source operators from all jobs.
The Flow Rate Chart is interesting. It shows sudden bursts of activity separated by periods of quiet. The source operator (FileSource, in this case) reads the file as fast as it can until it runs out of data. This fills the input port buffer of the Throttle, which slowly draws down that buffer at 40 tuples per second.
At just about the right time, when the Throttle operator is almost out of data, the same file is reported to the FileSource, which reads it again in one sharp burst. The chart shows the flow rate at zero most of the time with peaks up to just over 600 tuples per second spaced 45 seconds apart. Note that the chart shows a moving average over three seconds. In reality, the FileSource reads the entire file containing 1902 tuples in less than a second.
- Leave the job or jobs running.
Continue with the next lab. You will come back to the Console and your running job at the end of Lab 4 to learn more about a concept called back-pressure, which is unique to stream processing.