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jvm-1

JVM Tuning Flags​

  • Types
    • Boolean flags
      • -XX:+ FLagName Enable
      • -XX:- FlagName Disable
    • Flags that require parameter
      • -XX: FlagName=something
  • Ergonomics - Automatically tuning flags based on environment

Complete Performance Story​

Write better algos​

Write less code​

  • More objects = more allocation / retention => longer GC cycle => longer

Prematurely Optimize (What it means)​

  • Write clean, simple straightforward code that is simple to read and understand
  • Avoid code constructs that are known to be bad for performance
  • But don't pre-emptively make algorithmic / design changes until profiling has been done and bottlenecks are clear

The Database is the bottleneck​

  • Any part of the system that uses a CPU might be the bottleneck, it might not be java

Optimise for the common case​

  • Not all performance aspects are equally important - focus on the common ones
    • Profile code and focus on ops taking the most time
    • Apply Occam's Razor: "entities should not be multiplied beyond necessity"
    • Write simple algos for most common operations