Tools, Tools, Tools

Performance tuning is all about tools. Tools make things visibile—what is going on inside of an application, and in the application’s environment.

• CPU utilization is the higher the better (otherwise CPU is idling, waiting for I/O or locks).
• I/O utilization not always the higher the better.
• Network cannot sustain a 100% utilization rate.
• System monitor tools:
  • vmstat, iostat, nicstat (cpu, disk, network).
• Java monitor tools:
  • jcmd, jinfo, …
• Profiling tools:
  • Sampling: Less overhead, less accurate, each tool differs.
  • Instrumented: More intrusive.
  • Native: For profiling JVM.
  • Java Mission Control tool.
• -XX:+PrintFlagsFinal