JCP

Java concurrent programming

[TOC]

基础理论篇

CPU、OS，多任务抢占式
上下文切换
同步VS异步、并行VS并发、死锁VS活锁、

JVM实现机制

JMM：原子性、可见性、有序性
指令重排：Happen-Before规则、as-if-serail规则
临界区
Java对象头：JVM规范，排他锁，轻量级锁，偏向锁

JDK源码

synchronized
volatile
final
CAS
unsafe Java的指针
Lock(乐观锁、悲观锁、公平锁、非公平锁、独占锁、共享锁、可重入锁、自旋锁)，锁优化
AQS，LockSupport，ReentrantLock，ReentrantReadWriteLock，StampedLock，
并发容器：CopyOnWriteArrayList，ConcurrentLinkedQueue，LinkedBlockingQueue，ArrayBlockingQueue，PriorityBlockingQueue，DelayQueue，Collections.Synchronized wrapper
Atomic， LongAdder， LongAccumulator
Thread Group
ThreadPoolExecutor，ScheduledThreadPoolExecutor
ThreadLocal
Fork/Join
CountDownLatch
CyclicBarrier
Semaphore
并行任务：Future，CompletableFuture

Design Pattern in JCP

Singleton
Consumer & Producer
Pub & Sub
Template Method
Factory
Proxy
Disruptor

Thread state diagram

state option [new - runnable - terminated - waiting - waiting-timeout - blocked]
start
run
stop
interupt
join
wait
sleep
notify
yield
suspend
resume

Append

1/ distinguish [this thread] VS [current executing thread]
2/ daemon thread VS user thread
3/ CPU cache @sun.misc.Contented 字节填充 LongAddr  Array VS List
4/ 乐观锁 VS 悲观锁  sql for update -> 提升TPS
5/ ThreadLocal VS InheritableThreadLocal，ThreadLocal时内存泄露，使用完remove()
6/ LongAdder > AtomicLong    LongAccumulator
7/ CopyOnWriteArrayList COW（Redis的持久化） 弱一致性 平行宇宙
8/ StampedLock 带有version的optimistic Lock
9/ Future.get()，需带有Timeout参数，否则会因为线程池的一些RejectPolicy导致阻塞而永远不返回

JCP in action

JMH，IDEA插件
slf4j - logback - ArrayBlockingQueue
Tomcat NIO NioEndpoint Daemon(true)
Disruptor无锁环形内存队列
Akka - Actor - Scala - event-driven msg
Reactor Pattern - netty The purpose of the Reactor design pattern is to avoid the common problem of creating a thread for each message, request, and connection.
select, poll, epoll, and kqueue.
Thread-based architecture VS Event-driven architecture