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LockSupport??

1. ???LockSupport?

LockSupport ? Java ??????????????????????????????????? permit???????????????????????????

LockSupport ??????? park() ? unpark()??????????????????????????????????? Unsafe ?? native ????????????????

2. ????

• permit???0??????? park() ?????????????????????? unpark() ??????
• park() ??????????????????????????? unpark() ??????? 1?
• park(Object blocker)?????????????????????????

3. ????

• unpark(Thread thread)??????? permit ?? 1?????????????????permit ?????? 1??????? unpark() ??????????????
• unpark() ?????????????????????

4. LockSupport ???

• ?????LockSupport ???? permit ???????????????
• ???????????????????????????????????

5. ????

??????? LockSupport ?????????

public class LockSupportDemo {    public static void main(String[] args) {        Thread t1 = new Thread(() -> {            System.out.println(Thread.currentThread().getName() + "\t" + "??A??");            LockSupport.park();            System.out.println(Thread.currentThread().getName() + "\t" + "?B??");        }, "A");        t1.start();        Thread t2 = new Thread(() -> {            System.out.println(Thread.currentThread().getName() + "\t" + "??A??");            LockSupport.unpark(t1);        }, "B");        t2.start();    }}

6. ??????

• ???????????????????????????????????? park() ??????? permit ??????????????

• ???????????????? permit ??? 1??????? unpark() ??????????? park() ?????????????? permit ??? 0 ???????

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