Effective Java - Chapter 10 Concurrency

1. Use Synchronize access to shared mutable data
   - synchronize除了用來防止同時更改資料，也是用來保證會讀取到最新資料
   - synchronize要設在get與update
   - volatile
2. 不要過度使用Synchronize
   - alien => 只synchronize必要的部份, synchoronize越少越好 open call
   - 使用CopyOnWriteArrayList/Set
   - 讓client決定是否synchronize, 除非你自己有把握做的更好
   - static field一定要synchronize
3. Prefer executors
   - ExecutorService提供許多好用的機制
4. Prefer concurrency utilities to wait and notify
   - ExecutorService
   - Concurrent collections
   - CountDownLatch / Semaphore, CyclicBarrier / Exchanger
   - The standard idiom for using the wait method
   - Private lock object idiom
5. Any program that relies on the
   thread scheduler for correctness or performance is likely to be nonportable
6. thread groups are obsolete