Aritalab:Lecture/Programming/Java/Parallel2
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< Aritalab:Lecture | Programming | Java(Difference between revisions)
m (→Concurrentパッケージ) |
m (→Concurrentパッケージ) |
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Line 27: | Line 27: | ||
} | } | ||
− | void | + | void printStatus() { |
System.out.println(exec.getTaskCount() + " tasks" + " (active:" | System.out.println(exec.getTaskCount() + " tasks" + " (active:" | ||
+ exec.getActiveCount() + " queue:" + queue.size() + ")"); | + exec.getActiveCount() + " queue:" + queue.size() + ")"); | ||
Line 40: | Line 40: | ||
i++; | i++; | ||
} else { | } else { | ||
− | + | printStatus(); | |
Thread.sleep(500); | Thread.sleep(500); | ||
} | } | ||
Line 47: | Line 47: | ||
while (!exec.isTerminated()) { | while (!exec.isTerminated()) { | ||
− | + | printStatus(); | |
− | try { Thread.sleep( | + | try { Thread.sleep(500); } catch(Exception e) {} |
} | } | ||
System.out.println("FINISH"); | System.out.println("FINISH"); |
Latest revision as of 09:23, 2 July 2012
[edit] Concurrentパッケージ
非同期で多くの処理を行うときに便利なパッケージが java.util.concurrent です。簡単な使い方は
にあります。 ここでは 20 個のタスクを 4 スレッドで処理する例を紹介します。ThreadPoolExecutor の設定が面倒に見えますが Java6 のAPI仕様 をみながらパラメータを設定して下さい。ここでは長さを指定しない LinkedBlockingQueue を用いていますが、プログラム中で実行するタスクの数を調節しています。また終了するには exec.shutdown() を呼ぶのを忘れずにおこなって下さい。
import java.util.concurrent.BlockingQueue; import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; public class ThreadTest { BlockingQueue<Runnable> queue = new LinkedBlockingQueue<Runnable>(4); ThreadPoolExecutor exec = new ThreadPoolExecutor(4 /* corePoolSize */, 4 /* maxPoolSize */, 0 /* keepAliveTime */, TimeUnit.MILLISECONDS, queue); class Task extends Thread { int id; Task(int x) { id = x; } public void run() { try { Thread.sleep((int) (Math.random() * 1000)); } catch (Exception e) {} } } void printStatus() { System.out.println(exec.getTaskCount() + " tasks" + " (active:" + exec.getActiveCount() + " queue:" + queue.size() + ")"); } void test() { System.out.println("START"); try { for (int i = 0; i < 20;) { if (queue.remainingCapacity() > 0) { exec.execute(new Task(i)); i++; } else { printStatus(); Thread.sleep(500); } } } catch (Exception e) {} finally { exec.shutdown(); } while (!exec.isTerminated()) { printStatus(); try { Thread.sleep(500); } catch(Exception e) {} } System.out.println("FINISH"); } public static void main(String[] args) { ThreadTest T = new ThreadTest(); T.test(); } }