Profiling JVM Applications in Production

Many profilers, such as JVisualVM and jstack, will simply lie to your face about which call stacks are hottest and where your bottlenecks lie. Profiling in production environments has even more challenges, because you have to carefully manage overhead, account for other processes running on the system, and choose non-invasive tools that don't require an application restart.

We will build a simple checklist for verifying JVM application performance, and finding the area to focus on in a closer investigation. Then, we will experiment with two approaches for CPU profiling on Linux: the perf multi-tool, combined with perf-map-agent, and the async-profiler project, an innovative tool that brings perf together with traditional JVM profiling techniques. We will visualize stack traces using flame graphs, and understand where the CPU bottlenecks lie, through a series of hands-on labs.

In the second half of this workshop, we will talk about more complicated scenarios: diagnosing errors when opening files, tracing database queries, monitoring system I/O load, understanding the reasons for excessive garbage collection, figuring out why threads are blocked off-CPU, and more. Some of these tasks can be approached using perf, but others require a bleeding-edge technology—BPF and BCC.

Pre-Reading List:

• Introduction to JVM internals

Prerequisites, Skills, and Tools:

• Familiarity with shell scripting and basic commands
• Understanding of OS concepts such as processes, threads, memory
• Basic understanding of the JVM code execution model, GC, interactions with native code.