عرض عملي: مراقبة JIT باستخدام -XX:+PrintCompilation

خطوة بخطوة

1. Write a loop calling a small pricing method a million times, timing batches.
2. Run with -XX:+PrintCompilation; find the method's lines.
3. Read the tier column (levels 1-4; level 4 is C2) and notice made not entrant lines (deoptimization).
4. Print batch timings and match speed-ups to compilation events.
5. Planned mistake: time a single cold call and conclude the method is slow. Fix: warm up first, then measure many iterations (or use JMH).
6. Link to the lab: apply the same reasoning to the first 1,000 Shop checkout requests. Output format is version-specific; verify version before recording.