chapter seven

7 Profile your code before it ships

 

This chapter covers

  • Integrating daily profiling so performance problems become obvious
  • Browser developer tools that identify loading, runtime performance, and memory problems
  • Profiling backend services to find slow code and database query problems
  • Analyzing mobile app performance with Instruments and Android Studio Profiler
  • Measuring desktop application performance over extended sessions
  • Sustainable profiling habits that catch problems before code review

A performance problem found during development takes minutes to fix; the same problem found in production takes much longer. Budgets set the target, but they cannot tell you whether a feature branch is about to exceed that target. That is the job of profiling: to make performance visible, ideally before code leaves the developer's machine.

7.1 Web: Browser developer tools

7.1.1 Loading performance

7.1.2 Runtime behavior

7.1.3 Memory stability and leak detection

7.2 Backend: Profilers and query analyzers

7.2.1 Request tracing

7.2.2 Database query analysis

7.2.3 CPU and time profiling

7.2.4 Memory profiling

7.3 Mobile: Instruments and Android Profiler

7.3.1 CPU and time profiling

7.3.2 Rendering performance and energy

7.3.3 Memory profiling and leak detection

7.3.4 Network behavior under real-world conditions

7.3.5 Profile across device tiers

7.3.6 Profile hybrid and WebView content

7.4 Desktop: Performance profiling tools

7.4.1 Memory and resource profiling

7.4.2 CPU and time profiling

7.4.3 Rendering performance

7.5 Build a two-minute profiling habit

7.6 Summary