將任務提交給線程池給出RejectedExecutionException

Question

我正在開發一款在Android NDK中運行大多數本機代碼的社交遊戲。遊戲中有3個主要NDK並行線程：

1. 遊戲線程
2. 服務器通信線程
3. 主渲染線程（通過Renderer.onRender稱呼）

除此之外，關於java我們使用的是AdWhirl，它通過自己的ScheduledExecutorService產生自己的線程，但是我們用try-catch塊將每個調用都打包到「計劃」，「提交」，「發佈」，「開始」等，以捕獲RejectedExecutionException。然而，恐怖的RejectedExecutionException仍然出現在我們提交的每個新版本中。

來自Android Market的堆棧跟蹤對我來說幾乎沒有任何線索，我們的QA部門也發現難以確定問題，因爲它在測試過程中很難發生（只有我們的用戶報告崩潰）。它只會影響我們的用戶的一小部分，但它仍然

java.util.concurrent.RejectedExecutionException 
at   java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:1876) 
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:774) 
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1295) 
at android.os.AsyncTask.execute(AsyncTask.java:394) 
at c.onProgressUpdate(Unknown Source) 
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:432) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:123) 
at android.app.ActivityThread.main(ActivityThread.java:4632) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:521) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
at dalvik.system.NativeStart.main(Native Method) 

    java.util.concurrent.RejectedExecutionException: pool=128/128, queue=10/10 
at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:1961) 
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:794) 
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1315) 
at android.os.AsyncTask.execute(AsyncTask.java:394) 
at c.onProgressUpdate(Unknown Source) 
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:432) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:123) 
at android.app.ActivityThread.main(ActivityThread.java:3691) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:507) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605) 
at dalvik.system.NativeStart.main(Native Method) 

    java.util.concurrent.RejectedExecutionException 
at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:1876) 
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:774) 
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1295) 
at android.os.AsyncTask.execute(AsyncTask.java:394) 
at c.onProgressUpdate(Unknown Source) 
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:432) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:123) 
at android.app.ActivityThread.main(ActivityThread.java:4627) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:521) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
at dalvik.system.NativeStart.main(Native Method) 

Answer 1

你必須檢查你的代碼，它是創造遠（與大量安裝的基礎比較小的部分）是每週超過7000崩潰太多的AsyncTask比它允許的。

的policy設置爲

private static final int CORE_POOL_SIZE = 1; 
private static final int MAXIMUM_POOL_SIZE = 10; 
private static final int KEEP_ALIVE = 10; 

_{注：此變化在不同版本的Android}

Answer 2

，而你當然應該儘量讓事情儘可能有效，不存在任意限制你「允許」運行的線程數量，這完全取決於你如何構建你的代碼。

ThreadPoolExecutor類是極其記錄良好，是您看到的問題的起源。我會recommend reading through it，檢查出

首先我猜你用Ant構建這一點，並沒有使用到javac節點上的這些參數：

<javac debug="true" debuglevel="lines,vars,source" /> 

或許到那時你混淆顯然使用的原因什麼，通常會是一個堆棧跟蹤的最重要組成部分，而不是簡單的輸出：

c.onProgressUpdate(Unknown Source) 

這是當前ICS 4.0.4源的ThreadPoolExecutor。AbortPolicy，你可以看到它基本上是一個包羅萬象的那個總是拋出異常：

/** 
* A handler for rejected tasks that throws a 
* {@code RejectedExecutionException}. 
*/ 

public static class AbortPolicy implements RejectedExecutionHandler { 
    /** 
    * Creates an {@code AbortPolicy}. 
    */ 
    public AbortPolicy() { } 

    /** 
    * Always throws RejectedExecutionException. 
    * 
    * @param r the runnable task requested to be executed 
    * @param e the executor attempting to execute this task 
    * @throws RejectedExecutionException always. 
    */ 
    public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { 
     throw new RejectedExecutionException("Task " + r.toString() + 
              " rejected from " + 
              e.toString()); 
    } 
} 

此外，你會發現的DefaultHandler在ThreadPoolExecutor的頂部聲明：

private static final RejectedExecutionHandler defaultHandler = new AbortPolicy(); 

所以最後，如果你看一下默認構造的ThreadPoolExecutor：

public ThreadPoolExecutor(int corePoolSize, 
          int maximumPoolSize, 
          long keepAliveTime, 
          TimeUnit unit, 
          BlockingQueue<Runnable> workQueue, 
          ThreadFactory threadFactory) { 
    this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, 
     threadFactory, defaultHandler); 
} 

你會看到，它的實例本身使用它AbortPolicy類，這是它去故障RejectedExecutionHandler。

ThreadPoolExecutor還包括其他一些RejectedExecutionHandler子類，你可以設置爲默認值，比如：

/** 
* A handler for rejected tasks that silently discards the 
* rejected task. 
*/ 
public static class DiscardPolicy implements RejectedExecutionHandler { 
    /** 
    * Creates a {@code DiscardPolicy}. 
    */ 
    public DiscardPolicy() { } 

    /** 
    * Does nothing, which has the effect of discarding task r. 
    * 
    * @param r the runnable task requested to be executed 
    * @param e the executor attempting to execute this task 
    */ 
    public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { 
    } 
} 

其他3層ThreadPoolExecutor構造包括處理器選項，這樣你既可以使用創建它的一個實例不同的處理程序，或者創建你自己的子類，與此類似：在方法提交

package com.justinbuser; 

import java.util.concurrent.BlockingQueue; 
import java.util.concurrent.Executors; 
import java.util.concurrent.RejectedExecutionException; 
import java.util.concurrent.RejectedExecutionHandler; 
import java.util.concurrent.ThreadFactory; 
import java.util.concurrent.ThreadPoolExecutor; 
import java.util.concurrent.TimeUnit; 

public class NoThrowThreadPool extends ThreadPoolExecutor { 

    private static final RejectedExecutionHandler defaultHandler = new AdoptPolicy(); 

    public NoThrowThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) { 
     super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, Executors.defaultThreadFactory(), defaultHandler); 
     setRejectedExecutionHandler(defaultHandler); 
    } 

    public NoThrowThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, 
      ThreadFactory threadFactory) { 
     super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, defaultHandler); 
    } 

    public NoThrowThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, 
      RejectedExecutionHandler handler) { 
     super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, Executors.defaultThreadFactory(), defaultHandler); 
    } 

    public NoThrowThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, 
      ThreadFactory threadFactory, RejectedExecutionHandler handler) { 
     super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, defaultHandler); 
    } 

    public static class AdoptPolicy extends ThreadPoolExecutor.AbortPolicy { 

     @Override 
     public void rejectedExecution(Runnable r, ThreadPoolExecutor e) { 
      new RejectedExecutionException("Task " + r.toString() + " rejected from " + e.toString()).printStackTrace(); 
     } 
    } 
} 

Answer 3

新任務執行（一個java.lang.Runnable）將在執行程序關閉時以及執行程序對最大線程和工作隊列容量使用有限邊界並且已飽和時會被拒絕。

http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/util/concurrent/ThreadPoolExecutor.java