Chapter 14. Monitoring Structured Streaming Applications

Application monitoring is an integral part of any robust deployment. Monitoring provides insights on the application performance characteristics over time by collecting and processing metrics that quantify different aspects of the application’s performance, such as responsiveness, resource usage, and task-specific indicators.

Streaming applications have strict requirements regarding response times and throughput. In the case of distributed applications like Spark, the number of variables that we need to account for during the application’s lifetime are multiplied by the complexities of running on a cluster of machines. In the context of a cluster, we need to keep tabs on resource usage, like CPU, memory, and secondary storage across different hosts, from the perspective of each host, as well as a consolidated view of the running application.

For example, imagine an application running on 10 different executors. The total memory usage indicator shows a 15% increase, which might be within the expected tolerance for this application, but then, we notice that the increase comes from a single node. Such imbalance needs investigation because it will potentially cause a failure when that node runs out of memory. It also implies that there is potentially an unbalanced distribution of work that’s causing a bottleneck. Without proper monitoring, we would not observe such behavior in the first place.

The operational metrics of Structured ...

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