blocks|key|847815|text|您可以使用RejectedExecutionHandler在当前线程中运行任务。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|847816|public+static+final+ThreadPoolExecutor+CURRENT_THREAD_EXECUTOR+=+new+ThreadPoolExecutor(0,+0,+0,+TimeUnit.DAYS,+new+SynchronousQueue<Runnable>(),+new+RejectedExecutionHandler()+{
++++public+void+rejectedExecution(Runnable+r,+ThreadPoolExecutor+executor)+{
++++++++r.run();
++++}
});|code-block|syntax|javascript|847817|你永远只需要其中的一个。|847818|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can use the RejectedExecutionHandler to run the task in the current thread.

<pre><code>public static final ThreadPoolExecutor CURRENT_THREAD_EXECUTOR = new ThreadPoolExecutor(0, 0, 0, TimeUnit.DAYS, new SynchronousQueue&lt;Runnable&gt;(), new RejectedExecutionHandler() {
 public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
 r.run();
 }
});
</code></pre>

You only need one of these ever.

blocks|key|631426|text|这里有一个非常简单的Executor实现(注意，不是ExecutorService+)，它只使用当前线程。从"Java并发实践“(必读)中窃取这篇文章。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|631427|public+class+CurrentThreadExecutor+implements+Executor+{
++++public+void+execute(Runnable+r)+{
++++++++r.run();
++++}
}|code-block|syntax|javascript|631428|ExecutorService是一个更复杂的接口，但也可以用同样的方法来处理。|631429|entityMap^0|A|8|Q|F|0|0|0|F|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|N|$]]

Here's a really simple <code>Executor</code> (not <code>ExecutorService</code>, mind you) implementation that only uses the current thread. Stealing this from "Java Concurrency in Practice" (essential reading).

<pre><code>public class CurrentThreadExecutor implements Executor {
 public void execute(Runnable r) {
 r.run();
 }
}
</code></pre>

<code>ExecutorService</code> is a more elaborate interface, but could be handled with the same approach.

blocks|key|631486|text|我写了一个基于AbstractExecutorService的ExecutorService。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|631487|/**
+*+Executes+all+submitted+tasks+directly+in+the+same+thread+as+the+caller.
+*/
public+class+SameThreadExecutorService+extends+AbstractExecutorService+{

++++//volatile+because+can+be+viewed+by+other+threads
++++private+volatile+boolean+terminated;

++++@Override
++++public+void+shutdown()+{
++++++++terminated+=+true;
++++}

++++@Override
++++public+boolean+isShutdown()+{
++++++++return+terminated;
++++}

++++@Override
++++public+boolean+isTerminated()+{
++++++++return+terminated;
++++}

++++@Override
++++public+boolean+awaitTermination(long+theTimeout,+TimeUnit+theUnit)+throws+InterruptedException+{
++++++++shutdown();+//+TODO+ok+to+call+shutdown?+what+if+the+client+never+called+shutdown???
++++++++return+terminated;
++++}

++++@Override
++++public+List<Runnable>+shutdownNow()+{
++++++++return+Collections.emptyList();
++++}

++++@Override
++++public+void+execute(Runnable+theCommand)+{
++++++++theCommand.run();
++++}
}|code-block|syntax|javascript|631488|entityMap^0|7|N|V|F|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

I wrote an <code>ExecutorService</code> based on the <code>AbstractExecutorService</code>.

<pre><code>/**
 * Executes all submitted tasks directly in the same thread as the caller.
 */
public class SameThreadExecutorService extends AbstractExecutorService {

 //volatile because can be viewed by other threads
 private volatile boolean terminated;

 @Override
 public void shutdown() {
 terminated = true;
 }

 @Override
 public boolean isShutdown() {
 return terminated;
 }

 @Override
 public boolean isTerminated() {
 return terminated;
 }

 @Override
 public boolean awaitTermination(long theTimeout, TimeUnit theUnit) throws InterruptedException {
 shutdown(); // TODO ok to call shutdown? what if the client never called shutdown???
 return terminated;
 }

 @Override
 public List&lt;Runnable&gt; shutdownNow() {
 return Collections.emptyList();
 }

 @Override
 public void execute(Runnable theCommand) {
 theCommand.run();
 }
}
</code></pre>

blocks|key|847980|text|你可以使用芭乐的MoreExecutors.newDirectExecutorService()，或者MoreExecutors.directExecutor()，如果你不需要ExecutorService的话。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|847981|如果包含Guava太重了，你可以实现一些几乎一样好的东西：|847982|public+final+class+SameThreadExecutorService+extends+ThreadPoolExecutor+{
++private+final+CountDownLatch+signal+=+new+CountDownLatch(1);

++private+SameThreadExecutorService()+{
++++super(1,+1,+0,+TimeUnit.DAYS,+new+SynchronousQueue<Runnable>(),
++++++++new+ThreadPoolExecutor.CallerRunsPolicy());
++}

++@Override+public+void+shutdown()+{
++++super.shutdown();
++++signal.countDown();
++}

++public+static+ExecutorService+getInstance()+{
++++return+SingletonHolder.instance;
++}

++private+static+class+SingletonHolder+{
++++static+ExecutorService+instance+=+createInstance();++++
++}

++private+static+ExecutorService+createInstance()+{
++++final+SameThreadExecutorService+instance
++++++++=+new+SameThreadExecutorService();

++++//+The+executor+has+one+worker+thread.+Give+it+a+Runnable+that+waits
++++//+until+the+executor+service+is+shut+down.
++++//+All+other+submitted+tasks+will+use+the+RejectedExecutionHandler
++++//+which+runs+tasks+using+the++caller's+thread.
++++instance.submit(new+Runnable()+{
++++++++@Override+public+void+run()+{
++++++++++boolean+interrupted+=+false;
++++++++++try+{
++++++++++++while+(true)+{
++++++++++++++try+{
++++++++++++++++instance.signal.await();
++++++++++++++++break;
++++++++++++++}+catch+(InterruptedException+e)+{
++++++++++++++++interrupted+=+true;
++++++++++++++}
++++++++++++}
++++++++++}+finally+{
++++++++++++if+(interrupted)+{
++++++++++++++Thread.currentThread().interrupt();
++++++++++++}
++++++++++}
++++++++}});
++++return+Executors.unconfigurableScheduledExecutorService(instance);
++}
}|code-block|syntax|javascript|847983|entityMap|0|LINK|mutability|MUTABLE|url|https://google.github.io/guava/releases/19.0/api/docs/com/google/common/util/concurrent/MoreExecutors.html#newDirectExecutorService%2528%2529|1|https://google.github.io/guava/releases/19.0/api/docs/com/google/common/util/concurrent/MoreExecutors.html#directExecutor%2528%2529^0|8|14|1F|U|2G|F|8|14|0|1F|U|1|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]|$9|16|A|17|1|18]]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]|U|$5|P|Q|R|E|$S|V]]]]

You can use Guava's <a href="https://google.github.io/guava/releases/19.0/api/docs/com/google/common/util/concurrent/MoreExecutors.html#newDirectExecutorService%28%29" rel="noreferrer"><code>MoreExecutors.newDirectExecutorService()</code></a>, or <a href="https://google.github.io/guava/releases/19.0/api/docs/com/google/common/util/concurrent/MoreExecutors.html#directExecutor%28%29" rel="noreferrer"><code>MoreExecutors.directExecutor()</code></a> if you don't need an <code>ExecutorService</code>.

If including Guava is too heavy-weight, you can implement something almost as good:

<pre><code>public final class SameThreadExecutorService extends ThreadPoolExecutor {
 private final CountDownLatch signal = new CountDownLatch(1);

 private SameThreadExecutorService() {
 super(1, 1, 0, TimeUnit.DAYS, new SynchronousQueue&lt;Runnable&gt;(),
 new ThreadPoolExecutor.CallerRunsPolicy());
 }

 @Override public void shutdown() {
 super.shutdown();
 signal.countDown();
 }

 public static ExecutorService getInstance() {
 return SingletonHolder.instance;
 }

 private static class SingletonHolder {
 static ExecutorService instance = createInstance(); 
 }

 private static ExecutorService createInstance() {
 final SameThreadExecutorService instance
 = new SameThreadExecutorService();

 // The executor has one worker thread. Give it a Runnable that waits
 // until the executor service is shut down.
 // All other submitted tasks will use the RejectedExecutionHandler
 // which runs tasks using the caller's thread.
 instance.submit(new Runnable() {
 @Override public void run() {
 boolean interrupted = false;
 try {
 while (true) {
 try {
 instance.signal.await();
 break;
 } catch (InterruptedException e) {
 interrupted = true;
 }
 }
 } finally {
 if (interrupted) {
 Thread.currentThread().interrupt();
 }
 }
 }});
 return Executors.unconfigurableScheduledExecutorService(instance);
 }
}
</code></pre>

blocks|key|631568|text|Java+8风格：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|631569|Executor+e+=+Runnable::run;|offset|length|style|CODE|631570|entityMap^0|0|0|R|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Java 8 style:

<code>Executor e = Runnable::run;</code>

blocks|key|631607|text|出于测试的目的，我不得不使用相同的"CurrentThreadExecutorService“，虽然所有建议的解决方案都很好(特别是提到the+Guava+way的那个)，但我想出了一些与Peter+Lawrey建议的here类似的东西。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|631608|正如Axelle+Ziegler+here提到的，不幸的是，彼得的解决方案实际上并不起作用，因为在ThreadPoolExecutor中引入了对maximumPoolSize构造函数参数的检查(即maximumPoolSize不能为<=0)。|style|CODE|631609|为了规避这一点，我做了以下操作：|631610|private+static+ExecutorService+currentThreadExecutorService()+{
++++CallerRunsPolicy+callerRunsPolicy+=+new+ThreadPoolExecutor.CallerRunsPolicy();
++++return+new+ThreadPoolExecutor(0,+1,+0L,+TimeUnit.SECONDS,+new+SynchronousQueue<Runnable>(),+callerRunsPolicy)+{
++++++++@Override
++++++++public+void+execute(Runnable+command)+{
++++++++++++callerRunsPolicy.rejectedExecution(command,+this);
++++++++}
++++};
}|code-block|syntax|javascript|631611|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/14639686/3302776|1|https://stackoverflow.com/a/6581829/3302776|2|https://stackoverflow.com/questions/6581188/is-there-an-executorservice-that-uses-the-current-thread#comment9347588_6581829^0|1W|D|0|31|4|1|0|1D|I|20|F|2Q|F|38|3|H|4|2|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@$A|11|B|12|1|13]|$A|14|B|15|1|16]]|C|$]]|$1|D|3|E|5|6|7|17|8|@$A|18|B|19|F|G]|$A|1A|B|1B|F|G]|$A|1C|B|1D|F|G]|$A|1E|B|1F|F|G]]|9|@$A|1G|B|1H|1|1I]]|C|$]]|$1|H|3|I|5|6|7|1J|8|@]|9|@]|C|$]]|$1|J|3|K|5|L|7|1K|8|@]|9|@]|C|$M|N]]|$1|O|3|-4|5|6|7|1L|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]|W|$5|R|S|T|C|$U|X]]|Y|$5|R|S|T|C|$U|Z]]]]

I had to use the same "CurrentThreadExecutorService" for testing purposes and, although all suggested solutions were nice (particularly the one mentioning <a href="https://stackoverflow.com/a/14639686/3302776">the Guava way</a>), I came up with something similar to what Peter Lawrey suggested <a href="https://stackoverflow.com/a/6581829/3302776">here</a>.

As mentioned by Axelle Ziegler <a href="https://stackoverflow.com/questions/6581188/is-there-an-executorservice-that-uses-the-current-thread#comment9347588_6581829">here</a>, unfortunately Peter's solution won't actually work because of the check introduced in <code>ThreadPoolExecutor</code> on the <code>maximumPoolSize</code> constructor parameter (i.e. <code>maximumPoolSize</code> can't be <code>&lt;=0</code>).

In order to circumvent that, I did the following:

<pre><code>private static ExecutorService currentThreadExecutorService() {
 CallerRunsPolicy callerRunsPolicy = new ThreadPoolExecutor.CallerRunsPolicy();
 return new ThreadPoolExecutor(0, 1, 0L, TimeUnit.SECONDS, new SynchronousQueue&lt;Runnable&gt;(), callerRunsPolicy) {
 @Override
 public void execute(Runnable command) {
 callerRunsPolicy.rejectedExecution(command, this);
 }
 };
}
</code></pre>

What I am after is a compatible way to configure the use of a thread pool or not. Ideally the rest of the code should not be impacted at all. I could use a thread pool with 1 thread but that isn't quite what I want. Any ideas?

<pre><code>ExecutorService es = threads == 0 ? new CurrentThreadExecutor() : Executors.newThreadPoolExecutor(threads);

// es.execute / es.submit / new ExecutorCompletionService(es) etc
</code></pre>

Is there an ExecutorService that uses the current thread?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

我所追求的是一种兼容的方式来配置线程池的使用。理想情况下，代码的其余部分应该完全不受影响。我可以使用一个只有一个线程的线程池，但这并不是我想要的。有什么想法吗？ExecutorService es = threads == 0 ? new CurrentThreadExecutor() : Executors.newT...

问是否存在使用当前线程的ExecutorService？
EN

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问是否存在使用当前线程的ExecutorService？EN

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问是否存在使用当前线程的ExecutorService？
EN