《实务与陷阱》PPT课件

1、,國立交通大學資訊工程學系分散式系統實驗室 Distributed Computing Systems Lab,Java Thread Pool實務與陷阱,Agenda,Threads 數量上限 容量滿載的處理策略 異常處理 天有不測風雲,參考資料,Scott Oaks private static final int MAX_COUNT = 10000; public static void main(String args) Executor pool = Executors.newFixedThreadPool(POOL_SIZE); for (int i = 0; i MAX_COUN

2、T; +i) pool.execute( new ExecutorDemo(i) ); class ExecutorDemo implements Runnable public ExecutorDemo(int sn) /*/ public void run() /*/ ,Executors 懶人包,FixedThreadPool 固定數量 彈性不足 CachedThreadPool 自動伸縮 (0Integer.MAX_VALUE) 無法處理瞬間巨量,Demo 4,兼顧並行性與系統負載的 Thread Pool,ThreadPool DIY!,public class TestThread

3、Pool private static final int MAX_POOL_SIZE = 10; private static final int CORE_POOL_SIZE = 5 ; private static final long THREAD_KEEPALIVE_TIME = 60; private static final int QUEUE_SIZE = 3; / public static void main(String args) Executor pool = Executors.newThreadPoolExecutor( CORE_POOL_SIZE, MAX_P

4、OOL_SIZE, THREAD_KEEPALIVE_TIME, TimeUnit.SECONDS, new ArrayBlockingQueue(QUEUE_SIZE), new ThreadPoolExecutor.CallerRunsPolicy() ); /*/ ,異常處理,Demo 5,當 Thread Pool 遇見 exception,他抓得住我？,public class TestThreadPool / public static void main(String args) Executor pool = Executors.newFixedThreadPool(POOL_

5、SIZE); for (int i = 0; i MAX_COUNT; +i) try pool.execute( new ExecutorDemo(i) ); catch (Throwable e) /*/ class ExecutorDemo implements Runnable public ExecutorDemo(int sn) /*/ public void run() throw new RuntimeException(); ,Demo 6,除錯版：安裝自訂的 Thread.UncaughtExceptionHandler,安裝自訂的 ThreadFactory,public

6、 class TestThreadPool / public static void main(String args) Executor pool = Executors.newThreadPoolExecutor( CORE_POOL_SIZE, MAX_POOL_SIZE, THREAD_KEEPALIVE_TIME, TimeUnit.SECONDS, new ArrayBlockingQueue(QUEUE_SIZE), new SafeThreadFactory(), new ThreadPoolExecutor.CallerRunsPolicy() ); /*/ class Sa

7、feThreadFactory implements ThreadFactory /*下一頁*/ ,自訂 UncaughtExceptionHandler,class SafeThreadFactory implements ThreadFactory Override public Thread newThread(Runnable r) Thread thread = new Thread(r); thread.setUncaughtExceptionHandler( new Thread.UncaughtExceptionHandler() Override public void uncaughtException( Thread t, Throwable e) / ); return thread; ,Demo 7,懶人版：不讓 thread 丟出 exception,Thread 防呆策略,class ErrorProofThread implements Runnable / public void run() try /* m