Apache DefaultHttpClient - java.net.BindException：地址已在使用：連接

Question

我在訪問 Tomcat 8.5 web 服務器的 Java“客戶端”中運行性能測試。 在大約 13,000 個請求 HTTP 請求失敗並出現錯誤后，

org.apache.http.impl.client.DefaultHttpClient tryConnect
INFO: Retrying connect
java.net.BindException: Address already in use: connect
    at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:127)
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)
    at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:294)
    at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:643)
    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:479)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:805)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:784)

代碼是，

    for (int i = 0; i < 15000; i++) {
        try {
            if (i % 1000 == 0) System.out.println("Iterations: " + Integer.toString(i));
            HttpGet request = new HttpGet("http://localhost:9080");
            DefaultHttpClient client = new DefaultHttpClient();
            HttpResponse response = client.execute(request, new BasicHttpContext());
            HttpEntity entity = response.getEntity();
            EntityUtils.consume(entity);
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("Iterations: " + Integer.toString(i));
            System.exit(1);
        }
    }

如果我緩存 DefaultHttpClient，則不會發生錯誤。 也試過，

        request.releaseConnection();
        client.getConnectionManager().shutdown();

但不會改變錯誤。 該錯誤似乎不是由客戶端引起的。 如果我訪問 URL 中的另一個網站，那沒關系。 似乎是由 Windows 中的 Tomcat 用盡文件句柄或套接字資源或其他東西引起的。 如果我在它崩潰后立即將它作為另一個進程再次運行，它將在 1 次運行而不是 13,000 次中失敗，因此問題是 Tomcat 資源不足。 似乎 DefaultHttpClient 沒有關閉它的連接，或者 Tomcat 在 gc 發生之前沒有釋放它的連接。

使用 HTTPClient 4.2.5

有什么想法為什么會發生，或者如何解決？

Answer 1

我無法重現您遇到的相同錯誤。 無論如何，當我在單線程中運行您的示例時，我收到 NoRouteToHostException。

13:37:57.917 [main] DEBUG org.apache.http.impl.conn.BasicClientConnectionManager - Releasing connection org.apache.http.impl.conn.ManagedClientConnectionImpl@2c7ceffa
Iterations: 16329
java.net.NoRouteToHostException: Can't assign requested address (Address not available)
        at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)
        at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)
        at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)
        at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)
        at java.base/java.net.Socket.connect(Socket.java:591)
        at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:121)
        at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)
        at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:326)
        at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:605)
        at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:440)
        at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:835)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
    at com.demo.DemoApplication.main(DemoApplication.java:25)

您打開連接的速度比關閉連接的速度要快 - 關閉套接字在釋放它們可用於新連接之前處於 TIME_WAIT 狀態。

僅出於測試目的，您可以設置tcp_tw_reuse以允許重用 TIME_WAIT sockets。

在我的 OSX 上，我可以更改測試的最大段壽命，錯誤消失了。

sudo sysctl -w net.inet.tcp.msl=1000 net.inet.tcp.msl: 15000 -> 1000

DefaultHttpClient由BasicClientConnectionManager支持，它創建和管理單個連接，並且每次只為任何路由保留一個活動連接。

當連接被釋放回連接管理器時，它保持活動狀態以供重用並標記為可重用。

如果我緩存 DefaultHttpClient，則不會發生錯誤。

這正是解決方案。 我相信使用單個 http 客戶端並允許連接管理器完成其工作的正確方法。

apache 文檔中解釋了所有連接管理

4.2.5 已經很老了（2013 年 4 月）。 如果您開始一個新項目，那么在撰寫本文時更新到最新（4.5.12）是有意義的。

參考：

https://cwiki.apache.org/confluence/display/HTTPCOMPONENTS/FrequentlyAskedConnectionManagementQuestions

https://raby.sh/osx-where-are-my-time_wait.html

Answer 2

似乎您以錯誤的方式使用 HttpClient （即可能復制粘貼舊的舊代碼片段）

• 首先，一個客戶端就足夠了（對於一個線程）。
• 根據httpcomponents-client 文檔，最好使用池連接管理
• 您的回復應該被關閉

IE

  PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
  CloseableHttpClient client = HttpClients.custom()
          .setConnectionManager(cm)
          .build();
  HttpContext context = HttpClientContext.create();
  try {
    final HttpGet request = new HttpGet("http://localhost:9080");
    for(int i = 0; i < 15000; i++) {
      CloseableHttpResponse response = httpClient.execute(request, context);
      try {
        HttpEntity entity = response.getEntity();
        EntityUtils.consume(entity);
      } finally {
        response.close();
      }
    }
  } finally {
    client.close();
  }
}

Answer 3

最佳實踐是使用 MultiThread HttpClient 。 下面應該工作：

package com.demo.httpclient;

import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.DefaultClientConnection;
import org.apache.http.impl.conn.PoolingClientConnectionManager;
import org.apache.http.util.EntityUtils;

public class ThreadedHttpClientTest {

    private static URI rootUri = URI.create("http://localhost:8080/");
    private static int worker = 100;
    private static int count = 15000;

    private static HttpClient httpClient;

    public static void main(String[] args) throws Exception {

        long startTime = System.currentTimeMillis();
        PoolingClientConnectionManager poolingClientConnectionManager = new PoolingClientConnectionManager();
        poolingClientConnectionManager.setMaxTotal(worker);
        poolingClientConnectionManager.setDefaultMaxPerRoute(worker);

        httpClient = new DefaultHttpClient(poolingClientConnectionManager);

        List<Callable<Void>> workers = new ArrayList<Callable<Void>>();

        for (int i = 0; i < count; i++) {
            workers.add(new WorkerThread(httpClient, rootUri.toString()));
        }

        ExecutorService pool = Executors.newFixedThreadPool(worker);

        int i=0;
        for (Future<Void> future : pool.invokeAll(workers)) {
            future.get();
            System.out.println("Response " + i++);
        }

        System.out.println("Time Taken :: " + (System.currentTimeMillis() - startTime) + "ms");
        pool.shutdown();
    }

    static class WorkerThread implements Callable<Void> {

        HttpClient client;
        String url;

        public WorkerThread(HttpClient httpClient, String url) {
            this.client = httpClient;
            this.url = url;
        }

        @Override
        public Void call() throws Exception {
            HttpGet get = new HttpGet(url);
            HttpResponse response = client.execute(get, new DefaultClientConnection());
            HttpEntity entity = response.getEntity();
            EntityUtils.consume(entity);
            return null;
        }
    }
}