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

Question

bounty到期在7天内。该问题的答案有资格获得+ 500声望赏金。James想要引起更多关注来回答这个问题。

我正在访问Tomcat 8.5 Web服务器的Java“客户端”中进行性能测试。在大约13,000个请求之后，HTTP请求失败并显示错误，

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)

代码是，

    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);
        }
    }

如果我缓存DefaultHttpClient，则不会发生此错误。也尝试过，

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

但不会更改错误。该错误似乎不是由客户端引起的。如果我可以通过URL访问另一个网站，则可以。似乎是由Windows中的Tomcat耗尽了文件句柄或套接字资源等引起的。如果我在崩溃后立即将其作为另一个进程再次运行，它将在1次运行中失败，而不是13,000次，因此问题是Tomcat资源不足。似乎DefaultHttpClient没有关闭其连接，或者Tomcat在出现gc之前没有释放其连接。

任何想法为什么会发生或如何解决？

Answer 1

似乎您使用的是错误的方式使用HttpClient（例如，可能会复制粘贴旧的旧代码段）

• 首先，一个客户端就足够了（一个线程）。
• 根据httpcomponents-client documentation最好使用轮询的连接管理
• 您的回复应该关闭

即

  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();
  }
}