Effective Java 3/E summary chanpter 10 (Shorter version)

12 Apr 2021

Chanpter 10 : Concurrency

You can find the longer version of this summary here.

Concurrency satisfaction

• Exclusive execution: synchronized keyword
• Communication between threads: volatile field, both read and write sychronization

Synchronization failure

• Unresponsive, safety failure
  • Avoid calling alien methods
  • Minimize the synchronization area

Executor rather than thread, use task, use concurrency utility

• Normally use newCachedThreadPool
• Use newFixedThreadPool on heavy servers
• If you want full control, use ThreadPoolExecutor class directly
• ConcurrentHashMap, BlockingQueue, CountDownLatch, Semaphore, Phaser

Documentation

• Immutable: No need to sync (@Immutable)
• Unconditional thread safety: No need to sync (@ThreadSafe)
• Conditional thread safety: synchronization for some methods (@ThreadSafe)
• Not thread safe: should be wrapped with an external synchronization mechanism (@NotThreadSafe)

Caution

• Avoid using lazy initialization (synchroized, volatile)
• Avoid priority for Thread (using Thread.yield)