线程工厂ThreadFactory
我们在项目开发额过程中，如果有很多地方使用多线程，那么给线程命名是十分有必要的,这样当出现问题的时候就比较容易排查
创建线程池，使用默认的线程工厂
/** * 创建线程池 */ public static final ThreadPoolExecutor pool = new ThreadPoolExecutor( 20, 100, 5, TimeUnit.SECONDS, new ArrayBlockingQueue<>(100) );
测试
public static void main(String[] args) { pool.execute(() -> { Integer integer = getOrderInfo(); System.out.println(integer); }); pool.shutdown(); } private static Integer getOrderInfo(){ try { List<Integer> list = new ArrayList<>(); for (int i = 0 ; i < 10 ; i++){ list.add(i); } return list.get(11); }catch (Exception e){ throw new IndexOutOfBoundsException("数组越界"); } }
上面程序发生异常，数组下标越界，我们发现线程的名称是pool-1-thread-1，pool代表是哪一个线程池，如果再启动一个线程池 就是pool-2,一直按照3,4,5,一直递增,thread-1则是线程,也是递增,thread-2,thread-2,但是当我们系统业务复杂，服务很多， 根据这个报错很难找出是哪里的问题。
为线程设定名字
我们首先看一下默认的ThreadFactory，
static class DefaultThreadFactory implements ThreadFactory { private static final AtomicInteger poolNumber = new AtomicInteger(1); private final ThreadGroup group; private final AtomicInteger threadNumber = new AtomicInteger(1); private final String namePrefix; DefaultThreadFactory() { SecurityManager s = System.getSecurityManager(); group = (s != null) ? s.getThreadGroup() : Thread.currentThread().getThreadGroup(); namePrefix = "pool-" + poolNumber.getAndIncrement() + "-thread-"; } public Thread newThread(Runnable r) { Thread t = new Thread(group, r, namePrefix + threadNumber.getAndIncrement(), 0); if (t.isDaemon()) t.setDaemon(false); if (t.getPriority() != Thread.NORM_PRIORITY) t.setPriority(Thread.NORM_PRIORITY); return t; } }
不难看出在无参构造函数中使用了pool-作为前缀，那么这个我们可以自定义为自己的业务名称，ThreadFactory是一个接口，我们 实现它，并根据自己的需求去改就行，如下：
我们在构造函数中传了一个threadName，然后拼接成我们想要的
package thread.customthreadpool.threadFactory; import java.util.concurrent.Executors; import java.util.concurrent.ThreadFactory; import java.util.concurrent.atomic.AtomicInteger; /** * 自定义线程工厂 * * 线程工厂可以设置线程信息 */ public class MyThreadFactory implements ThreadFactory { private static final AtomicInteger poolNumber = new AtomicInteger(1); private final ThreadGroup group; private final AtomicInteger threadNumber = new AtomicInteger(1); private final String namePrefix; /** * 构造函数传入我们想业务需要的线程名字threadName，方便发生异常是追溯 * @param threadName */ public MyThreadFactory(String threadName) { SecurityManager s = System.getSecurityManager(); group = (s != null) ? s.getThreadGroup() : Thread.currentThread().getThreadGroup(); if (threadName == null || threadName.isEmpty()){ threadName = "pool"; } namePrefix = threadName + poolNumber.getAndIncrement() + "-thread-"; } public Thread newThread(Runnable r) { Thread t = new Thread(group, r, namePrefix + threadNumber.getAndIncrement(), 0); if (t.isDaemon()) t.setDaemon(false); if (t.getPriority() != Thread.NORM_PRIORITY) t.setPriority(Thread.NORM_PRIORITY); return t; } }
然后将其加入线程池
/** * 创建线程池 */ public static final ThreadPoolExecutor pool = new ThreadPoolExecutor( 20, 100, 5, TimeUnit.SECONDS, new ArrayBlockingQueue<>(100), new MyThreadFactory("business") );
当发生异常时，我们就能清晰的看到是哪一个模块的问题，能够快速的去排查
