[eight part essay] usage scenarios and features of JUC

Thread safety

Unified management thread

Thread pool

Start and stop thread pool

• perform execute()
• Non violent cessation shutdown() —— No new assignments , Perform all tasks and stop , Set up isSutdown: true
  • Finally stop isTerminated()
• Check if it stops awaitTermination(3, TImeUnit.SECONDS) —— wait for 3s, Check whether the thread stops
• The violence stopped shutdownNow()—— Stop the current task , Return the task blocking the queue .（ It means a bit of service degradation ）

4 Type of rejection policy

Own thread pool

It's all... In essence ThreadPoolExecutor

jdk Packaged FixedThreadPool

• Use unbounded queues , Based on the list ;—— Easy to produce OOM

jdk Packaged SingleThreadPool

• It's also an unbounded queue , ditto

jdk Packaged CacheThreadPool

• Queues do not store elements , Create thread pool directly

jdk Packaged ScheduleThreadPool

• Time related

jdk Packaged WorkStealingPool

• Cut the overall task into sub tasks （ recursive ）, It can be executed in parallel

Create your own thread pool

Inherit ThreadPoolExecutor

Hook function

Coordination between threads