ThreadLocal线程局部变量

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一、ThreadLocal简介

1.是什么

2.能干嘛

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①：阿里手册对使用ThreadLocal的规范

@Data
@AllArgsConstructor
@NoArgsConstructor
class House{
    ThreadLocal<Integer> saleVolume=ThreadLocal.withInitial(()->0);
    public void saleVolumeByThreadLocal(int size){
        saleVolume.set(saleVolume.get()+size);
    }
}
/**
 * 需求：5个销售卖完随机数房子，各自独立销售额度，自己业绩按提成走
 */
public class ThreadLocalDemo {

    public static void main(String[] args) throws InterruptedException {
        ExecutorService threadPool = Executors.newFixedThreadPool(3);
        House house=new House();
        for (int i = 1; i <=10; i++) {
                threadPool.submit(()->{
                    try{
                        Integer before = house.saleVolume.get();
                        int size = new Random().nextInt(5) + 1;
                        house.saleVolumeByThreadLocal(size);
                        Integer after = house.saleVolume.get();
                        System.out.println(Thread.currentThread().getName()+" before "+before+" after "+after);
                    }finally {
                        house.saleVolume.remove();
                    }
                });
        }
    }
}

pool-1-thread-2 before 0 after 3
pool-1-thread-1 before 0 after 4
pool-1-thread-2 before 0 after 3
pool-1-thread-1 before 0 after 1
pool-1-thread-1 before 0 after 2
pool-1-thread-1 before 0 after 2
pool-1-thread-1 before 0 after 4
pool-1-thread-3 before 0 after 5
pool-1-thread-1 before 0 after 3
pool-1-thread-2 before 0 after 3

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②总结

二、ThreadLocal源码分析

1. Thread、ThreadLocal、ThreadLocalMap关系

①Thread、ThreadLocal

②：ThreadLocal、ThreadLocalMap

③：三者总概括

2.总结

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三、ThreadLocal内存泄漏问题

1.什么是内存泄漏

2.谁惹的祸

①：Why

②：强引用、软引用、弱引用、虚引用分别是什么？

整体架构

强引用

软引用

弱引用

虚引用

构造方法

引用队列

GCRoots和和四大引用小总结

③：为什么要用弱引用

四、总结