阿里TTL异步执行上下文对象传递

Github地址：https://github.com/alibaba/transmittable-thread-local

验证对象异步传递示例：

package com.alibaba.ttl.threadpool.agent.demo;import java.util.ArrayList;import java.util.List;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Future;import java.util.concurrent.TimeUnit;import com.alibaba.ttl.TransmittableThreadLocal;public final class AgentDemo {    static TransmittableThreadLocal<String> stringTransmittableThreadLocal = new TransmittableThreadLocal<String>();    static TransmittableThreadLocal<Person> personReferenceTransmittableThreadLocal = new TransmittableThreadLocal<Person>() {        @Override        protected Person initialValue() {            return new Person("unnamed", -1);        }    };    static TransmittableThreadLocal<Person> personCopyTransmittableThreadLocal = new TransmittableThreadLocal<Person>() {        @Override        protected Person copy(Person parentValue) {            // copy value to child thread            return new Person(parentValue.getName(), parentValue.getAge());        }        @Override        protected Person initialValue() {            return new Person("unnamed", -1);        }    };        private AgentDemo() {    throw new InstantiationError( "Must not instantiate this class" );    }    public static void main(String[] args) throws Exception {        ExecutorService executorService = Executors.newFixedThreadPool(3);        expandThreadPool(executorService);        stringTransmittableThreadLocal.set("foo - main");        personReferenceTransmittableThreadLocal.set(new Person("jerry - reference", 1));        personCopyTransmittableThreadLocal.set(new Person("Tom - value", 2));        printTtlInstancesInfo("Main - Before execution of thread pool");        Future<?> submit = executorService.submit(new Runnable() {            @Override            public void run() {                printTtlInstancesInfo("Thread Pool - enter");                stringTransmittableThreadLocal.set("foo - modified in thread pool");                personReferenceTransmittableThreadLocal.get().setName("jerry - reference - modified in thread pool");                personCopyTransmittableThreadLocal.get().setName("Tom - value - modified in thread pool");                printTtlInstancesInfo("Thread Pool - leave");            }        });        submit.get();        printTtlInstancesInfo("Main - After execution of thread pool");        executorService.shutdown();        if (!executorService.awaitTermination(3, TimeUnit.SECONDS)) {            System.exit(1);        }    }    public static void expandThreadPool(ExecutorService executor) throws Exception {        List<Future<?>> ret = new ArrayList<Future<?>>();        for (int i = 0; i < 3; ++i) {            Future<?> submit = executor.submit(new Runnable() {                @Override                public void run() {                    try {                        Thread.sleep(1000);                    } catch (InterruptedException e) {                        throw new RuntimeException(e);                    }                }            });            ret.add(submit);        }        for (Future<?> future : ret) {            future.get();        }    }    static void printTtlInstancesInfo(String msg) {        System.out.println("====================================================");        System.out.println(msg);        System.out.println("====================================================");        System.out.println("stringTransmittableThreadLocal: " + stringTransmittableThreadLocal.get());        System.out.println("personReferenceTransmittableThreadLocal: " + personReferenceTransmittableThreadLocal.get());        System.out.println("personCopyTransmittableThreadLocal: " + personCopyTransmittableThreadLocal.get());    }    public static class Person {        String name;        int age;        public String getName() {            return name;        }        public void setName(String name) {            this.name = name;        }        public int getAge() {            return age;        }        public void setAge(int age) {            this.age = age;        }        public Person(String name, int age) {            this.name = name;            this.age = age;        }        @Override        public String toString() {            return "Person{" +                    "name='" + name + '\'' +                    ", age=" + age +                    '}';        }    }}

测试结果：

====================================================Main - Before execution of thread pool====================================================stringTransmittableThreadLocal: foo - mainpersonReferenceTransmittableThreadLocal: Person{name='jerry - reference', age=1}personCopyTransmittableThreadLocal: Person{name='Tom - value', age=2}====================================================Thread Pool - enter====================================================stringTransmittableThreadLocal: nullpersonReferenceTransmittableThreadLocal: Person{name='unnamed', age=-1}personCopyTransmittableThreadLocal: Person{name='unnamed', age=-1}====================================================Thread Pool - leave====================================================stringTransmittableThreadLocal: foo - modified in thread poolpersonReferenceTransmittableThreadLocal: Person{name='jerry - reference - modified in thread pool', age=-1}personCopyTransmittableThreadLocal: Person{name='Tom - value - modified in thread pool', age=-1}====================================================Main - After execution of thread pool====================================================stringTransmittableThreadLocal: foo - mainpersonReferenceTransmittableThreadLocal: Person{name='jerry - reference', age=1}personCopyTransmittableThreadLocal: Person{name='Tom - value', age=2}

分析：

-Before 初始化线程输出

-enter  线程重新设置传递对象的值，但并未提交，所以对象是一个默认的实例输出

-leave submit提交对象修改，对象值被修改传递赋值

-after 输出最终结果