假设我有一个利用Executor框架的应用程序
Executors.newSingleThreadExecutor().submit(new Runnable(){
@Override
public void run(){
// do stuff
}
}
当我在调试器中运行此应用程序时,将创建一个具有以下(默认)名称的线程:thread [pool-1-thread-1]。正如您所看到的,这并不是非常有用,而且据我所知,Executor框架并没有提供一种简单的方法来命名创建的线程或线程池。
那么,如何为线程/线程池提供名称呢?例如,Thread[fopool - foothread]。
你可以提供一个ThreadFactory给newSingleThreadScheduledExecutor(ThreadFactory)。工厂将负责创建线程,并能够为它们命名。
引用Javadoc的话:
Creating new threads
New threads are created using a ThreadFactory. If not otherwise specified, a Executors.defaultThreadFactory() is used, that creates threads to all be in the same ThreadGroup and with the same NORM_PRIORITY priority and non-daemon status. By supplying a different ThreadFactory, you can alter the thread's name, thread group, priority, daemon status, etc. If a ThreadFactory fails to create a thread when asked by returning null from newThread, the executor will continue, but might not be able to execute any tasks
Oracle对此有一个开放的RFE。从甲骨文员工的评论来看,他们似乎不理解这个问题,也不会解决。在JDK中支持它是非常简单的事情之一(不会破坏向后兼容性),所以RFE被误解有点遗憾。
如前所述,您需要实现自己的ThreadFactory。如果您不想为了这个目的而引入Guava或Apache Commons,我在这里提供一个ThreadFactory实现供您使用。除了能够将线程名前缀设置为“pool”之外,它与您从JDK中获得的内容完全相似。
package org.demo.concurrency;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;
/**
* ThreadFactory with the ability to set the thread name prefix.
* This class is exactly similar to
* {@link java.util.concurrent.Executors#defaultThreadFactory()}
* from JDK8, except for the thread naming feature.
*
* <p>
* The factory creates threads that have names on the form
* <i>prefix-N-thread-M</i>, where <i>prefix</i>
* is a string provided in the constructor, <i>N</i> is the sequence number of
* this factory, and <i>M</i> is the sequence number of the thread created
* by this factory.
*/
public class ThreadFactoryWithNamePrefix implements ThreadFactory {
// Note: The source code for this class was based entirely on
// Executors.DefaultThreadFactory class from the JDK8 source.
// The only change made is the ability to configure the thread
// name prefix.
private static final AtomicInteger poolNumber = new AtomicInteger(1);
private final ThreadGroup group;
private final AtomicInteger threadNumber = new AtomicInteger(1);
private final String namePrefix;
/**
* Creates a new ThreadFactory where threads are created with a name prefix
* of <code>prefix</code>.
*
* @param prefix Thread name prefix. Never use a value of "pool" as in that
* case you might as well have used
* {@link java.util.concurrent.Executors#defaultThreadFactory()}.
*/
public ThreadFactoryWithNamePrefix(String prefix) {
SecurityManager s = System.getSecurityManager();
group = (s != null) ? s.getThreadGroup()
: Thread.currentThread().getThreadGroup();
namePrefix = prefix + "-"
+ poolNumber.getAndIncrement()
+ "-thread-";
}
@Override
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;
}
}
当您想要使用它时,只需利用所有Executors方法都允许您提供自己的ThreadFactory这一事实。
This
Executors.newSingleThreadExecutor();
将给出一个ExecutorService,其中线程命名为pool-N-thread-M,但使用
Executors.newSingleThreadExecutor(new ThreadFactoryWithNamePrefix("primecalc"));
您将得到一个ExecutorService,其中线程名为primecalc-N-thread-M。瞧!
如果使用Spring,可以为CustomizableThreadFactory设置线程名前缀。
例子:
ExecutorService alphaExecutor =
Executors.newFixedThreadPool(10, new CustomizableThreadFactory("alpha-"));
或者,您可以使用ThreadPoolExecutorFactoryBean将ExecutorService创建为Spring bean——然后所有线程都将以beanName-前缀命名。
@Bean
public ThreadPoolExecutorFactoryBean myExecutor() {
ThreadPoolExecutorFactoryBean executorFactoryBean = new ThreadPoolExecutorFactoryBean();
// configuration of your choice
return executorFactoryBean;
}
在上面的例子中,线程将以myExecutor-前缀命名。您可以显式地将前缀设置为不同的值(例如。通过在工厂bean上设置executorFactoryBean.setThreadNamePrefix("myPool-")来实现。
ThreadFactory扩展
公共接口
根据需要创建新线程的对象。使用线程工厂消除了对新线程的硬连接,使应用程序能够使用特殊的线程子类、优先级等。
线程newThread(可运行r)
构造一个新的线程。实现也可以初始化优先级、名称、守护进程状态、线程组等。
示例代码:
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
import java.util.concurrent.ThreadPoolExecutor.DiscardPolicy;
class SimpleThreadFactory implements ThreadFactory {
String name;
AtomicInteger threadNo = new AtomicInteger(0);
public SimpleThreadFactory (String name){
this.name = name;
}
public Thread newThread(Runnable r) {
String threadName = name+":"+threadNo.incrementAndGet();
System.out.println("threadName:"+threadName);
return new Thread(r,threadName );
}
public static void main(String args[]){
SimpleThreadFactory factory = new SimpleThreadFactory("Factory Thread");
ThreadPoolExecutor executor= new ThreadPoolExecutor(1,1,60,
TimeUnit.SECONDS,new ArrayBlockingQueue<Runnable>(1),new ThreadPoolExecutor.DiscardPolicy());
final ExecutorService executorService = Executors.newFixedThreadPool(5,factory);
for ( int i=0; i < 100; i++){
executorService.submit(new Runnable(){
public void run(){
System.out.println("Thread Name in Runnable:"+Thread.currentThread().getName());
}
});
}
executorService.shutdown();
}
}
输出:
java SimpleThreadFactory
thread no:1
thread no:2
Thread Name in Runnable:Factory Thread:1
Thread Name in Runnable:Factory Thread:2
thread no:3
thread no:4
Thread Name in Runnable:Factory Thread:3
Thread Name in Runnable:Factory Thread:4
thread no:5
Thread Name in Runnable:Factory Thread:5
等
您可以编写自己的ThreadFactory实现,例如使用一些现有的实现(如defaultThreadFactory),并在最后更改名称。
实现ThreadFactory的例子:
class ThreadFactoryWithCustomName implements ThreadFactory {
private final ThreadFactory threadFactory;
private final String name;
public ThreadFactoryWithCustomName(final ThreadFactory threadFactory, final String name) {
this.threadFactory = threadFactory;
this.name = name;
}
@Override
public Thread newThread(final Runnable r) {
final Thread thread = threadFactory.newThread(r);
thread.setName(name);
return thread;
}
}
和用法:
Executors.newSingleThreadExecutor(new ThreadFactoryWithCustomName(
Executors.defaultThreadFactory(),
"customName")
);
这是我的定制工厂,为线程转储分析器提供定制名称。通常我只是给tf=null来重用JVM默认的线程工厂。本网站有比较先进的螺纹工厂。
public class SimpleThreadFactory implements ThreadFactory {
private ThreadFactory tf;
private String nameSuffix;
public SimpleThreadFactory (ThreadFactory tf, String nameSuffix) {
this.tf = tf!=null ? tf : Executors.defaultThreadFactory();
this.nameSuffix = nameSuffix;
}
@Override public Thread newThread(Runnable task) {
// default "pool-1-thread-1" to "pool-1-thread-1-myapp-MagicTask"
Thread thread=tf.newThread(task);
thread.setName(thread.getName()+"-"+nameSuffix);
return thread;
}
}
- - - - -
ExecutorService es = Executors.newFixedThreadPool(4, new SimpleThreadFactory(null, "myapp-MagicTask") );
为了方便起见,这是一个用于调试的线程转储循环。
ThreadMXBean mxBean=ManagementFactory.getThreadMXBean();
long[] tids = mxBean.getAllThreadIds();
System.out.println("------------");
System.out.println("ThreadCount="+tids.length);
for(long tid : tids) {
ThreadInfo mxInfo=mxBean.getThreadInfo(tid);
if (mxInfo==null) {
System.out.printf("%d %s\n", tid, "Thread not found");
} else {
System.out.printf("%d %s, state=%s, suspended=%d, lockowner=%d %s\n"
, mxInfo.getThreadId(), mxInfo.getThreadName()
, mxInfo.getThreadState().toString()
, mxInfo.isSuspended()?1:0
, mxInfo.getLockOwnerId(), mxInfo.getLockOwnerName()
);
}
}
正如其他答案已经说过的,您可以创建并使用自己的java.util.concurrent.ThreadFactory接口的实现(不需要外部库)。
我把我的代码粘贴在下面,因为它不同于以前的答案,因为它使用字符串。Format方法,并将线程的基名称作为构造函数参数:
import java.util.concurrent.ThreadFactory;
public class NameableThreadFactory implements ThreadFactory{
private int threadsNum;
private final String namePattern;
public NameableThreadFactory(String baseName){
namePattern = baseName + "-%d";
}
@Override
public Thread newThread(Runnable runnable){
threadsNum++;
return new Thread(runnable, String.format(namePattern, threadsNum));
}
}
这是一个用法的例子:
ThreadFactory threadFactory = new NameableThreadFactory("listenerThread");
final ExecutorService executorService = Executors.newFixedThreadPool(5, threadFactory);
编辑:使我的ThreadFactory实现线程安全,感谢@mchernyakov指出这一点。
尽管在ThreadFactory文档中没有任何地方说它的实现必须是线程安全的,但DefaultThreadFactory是线程安全的事实是一个很大的提示:
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;
public class NameableThreadFactory implements ThreadFactory{
private final AtomicInteger threadsNum = new AtomicInteger();
private final String namePattern;
public NameableThreadFactory(String baseName){
namePattern = baseName + "-%d";
}
@Override
public Thread newThread(Runnable runnable){
return new Thread(runnable, String.format(namePattern, threadsNum.addAndGet(1)));
}
}
我想我要抛出一些简单的例子,只是为了让选项都在那里:
唯一的数字(也可以把它放到一个方法中):
AtomicInteger threadNum = new AtomicInteger(0);
ExecutorService e = Executors.newSingleThreadExecutor(r -> new Thread(r, "my-name-" + threadNum.incrementAndGet()));
唯一的编号和“可能”唯一的名称(如果您正在生成新的Runnable对象)。如果启动线程是在一个被多次调用的方法中,例如:
AtomicInteger threadNum = new AtomicInteger(0);
ExecutorService e = Executors.newSingleThreadExecutor(r -> new Thread(r, "my-name-" + threadNum.incrementAndGet() + "-" + r.hashCode()));
如果你真的想每次都有一个唯一的名字,你就需要一个带有静态变量的类(也可以在那里添加一个静态池号前缀,参见其他答案)。
在JDK < 8中等价(你不需要一个新的类,或者可以从一个方法中返回一个ThreadFactory):
Executors.newSingleThreadExecutor(new ThreadFactory() {
AtomicInteger threadCount = new AtomicInteger(0);
@Override
public Thread newThread(Runnable r) {
return new Thread(r, "your-name-" + threadCount.getAndIncrement() + "-" + r.hashCode()); // could also use Integer.toHexString(r.hashCode()) for shorter
}
}));
并且可以将其作为变量,作为“you-name-”方面的方法。或者像其他答案一样,使用一个单独的带有构造函数的类。