Question

我需要你的建议。我正在尝试制作一些可以批量检查av的代码。连接速度到多个线程中的URL。代码有效。但是我不明白为什么当我使用4个线程时，av.connection速度是150ms并且使用20个线程它可以提升到500-600ms？有线索吗？

下面的代码应该如何工作的想法：主要是我启动一个“ThreadManager”，它启动多个将与URL建立连接的线程。 URL保存在同步的ArrayList中，结果也写在同步的ArrayList中。

package URLConnectionSpeedChecker; 
public class ThreadManager implements Runnable{

private static Base base;

@Override
public void run() {
    base = new Base();
    Thread[] threads = new Thread[4];
    for (int i = 0; i < 4; i++ ) {
        CheckerThread checkerThread = new CheckerThread(base);
        Thread thread = new Thread(checkerThread);
        threads[i] = thread;
    }
    for (Thread x : threads) {
        x.start();
    }
    for (Thread x : threads) {
        try {
            x.join();

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public static Base getBase (){
    return base;
}

在线程中运行的代码：

package URLConnectionSpeedChecker;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;

public class CheckerThread implements Runnable {

private static Base base;

CheckerThread(Base base) {
    this.base = base;
}

@Override
public void run() {

    while (base.getIsOutlistOfURLs() == false) {

        long timeDifference = 0;

        try {
            timeDifference = connectTime(base.getListOfUrls());
        } catch (SocketTimeoutException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        addTimeDifference(base.getListOfTimeDifferences(), timeDifference);
    }
}


public long connectTime(ArrayList<String> list) throws IOException {
    long startTime = 0;
    long finishTime = 0;
    long timeDifference;

    URL url = getURL(list);
    if (!(url == null)) {
        startTime = System.currentTimeMillis();
        URLConnection urlConnection = url.openConnection();
        urlConnection.setConnectTimeout(3000);
        urlConnection.connect();
        finishTime = System.currentTimeMillis();
        timeDifference = finishTime - startTime;
        return timeDifference;
    } else {
        return 0;
    }
}

synchronized public void addTimeDifference(ArrayList<Long> list, long timeDifference) {
    list.add(timeDifference);
}

synchronized public URL getURL(ArrayList<String> list) {
    if (list.size() > 0) {

        if (list.get(0).length() > 0) {
            URL url = null;
            try {
                url = new URL(list.get(0));
            } catch (MalformedURLException e) {
                e.printStackTrace();
            }
            list.remove(0);
            return url;
        } else if (list.get(0).length() < 0) {
            list.remove(0);
            return null;
        } else {
            return null;
        }
    } else {
        base.setIsOutlistOfURLs();
        return null;
    }
}
}


}

根据线程数量，URL的连接速度不同

0 个答案: