Java ThreadFactory:为什么一个使用works,而另一个不使用';T
在下面的程序中,代码挂起,同时尝试在方法Java ThreadFactory:为什么一个使用works,而另一个不使用';T,java,executorservice,Java,Executorservice,在下面的程序中,代码挂起,同时尝试在方法second()中的Future上执行get()!为什么呢?两个executor服务之间的唯一区别是它们使用的ThreadFactory。无论是使用计数为1的newSingleThreadExecutor还是newFixedThreadPool package me.test; import java.util.concurrent.Callable; import java.util.concurrent.ExecutionException; impo
second()
中的Future
上执行get()
!为什么呢?两个executor服务之间的唯一区别是它们使用的ThreadFactory
。无论是使用计数为1的newSingleThreadExecutor
还是newFixedThreadPool
package me.test;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadFactory;
public class ExecutorServiceTest {
ThreadFactory tf1 = new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread t = Executors.defaultThreadFactory().newThread(r);
t.setDaemon(true);
t.setName("tf1-thread");
return t;
}
};
ThreadFactory tf2 = new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread("tf2-thread");
t.setDaemon(true);
return t;
}
};
ExecutorService service1 = Executors.newSingleThreadExecutor(tf1);
ExecutorService service2 = Executors.newSingleThreadExecutor(tf2);
Callable<Integer> callable = new Callable<Integer>() {
@Override
public Integer call() throws Exception {
return 0;
}
};
public static void main(String[] args) throws ExecutionException, InterruptedException {
ExecutorServiceTest executorTest = new ExecutorServiceTest();
executorTest.first(); // this returns
executorTest.second(); // this hangs
System.exit(0);
}
void first() throws ExecutionException, InterruptedException {
Future<Integer> future = service1.submit(callable);
int result = future.get();
System.out.println("result=" + result);
}
void second() throws ExecutionException, InterruptedException {
Future<Integer> future = service2.submit(callable);
int result = future.get();
System.out.println("result=" + result);
}
}
package me.test;
导入java.util.concurrent.Callable;
导入java.util.concurrent.ExecutionException;
导入java.util.concurrent.ExecutorService;
导入java.util.concurrent.Executors;
导入java.util.concurrent.Future;
导入java.util.concurrent.ThreadFactory;
公共类测试{
ThreadFactory tf1=新的ThreadFactory(){
@凌驾
公共线程newThread(可运行的r){
线程t=Executors.defaultThreadFactory().newThread(r);
t、 setDaemon(true);
t、 setName(“tf1线程”);
返回t;
}
};
ThreadFactory tf2=新的ThreadFactory(){
@凌驾
公共线程newThread(可运行的r){
线程t=新线程(“tf2线程”);
t、 setDaemon(true);
返回t;
}
};
ExecutorService service1=Executors.newSingleThreadExecutor(tf1);
ExecutorService service2=Executors.newSingleThreadExecutor(tf2);
Callable Callable=new Callable(){
@凌驾
公共整数调用()引发异常{
返回0;
}
};
公共静态void main(字符串[]args)引发ExecutionException、InterruptedException{
ExecutorServiceTest executorTest=新的ExecutorServiceTest();
executorTest.first();//返回
executorTest.second();//此挂起
系统出口(0);
}
void first()引发ExecutionException,InterruptedException{
Future=service1.提交(可调用);
int result=future.get();
System.out.println(“结果=”+结果);
}
void second()引发ExecutionException,InterruptedException{
Future=service2.提交(可调用);
int result=future.get();
System.out.println(“结果=”+结果);
}
}
您的第一个工厂创建了一个运行指定可运行线程的线程:
Thread t = Executors.defaultThreadFactory().newThread(r);
而在第二个工厂中,您只是忘记为创建的线程提供runnable:
Thread t = new Thread("tf2-thread");
因此,在第二种情况下,runnable永远不会运行,因此未来永远不会得到值
将第二种情况下的线程创建更改为
Thread t = new Thread(r, "tf2-thread");