Mac 上 Apache HttpClient 4.5 的“连接重置”异常

Question

我需要达到 1000 个线程来同时发送 HTTP 请求。然而，在 Mac 上，我似乎遇到了一些限制，这导致 Apache HTTPClient 返回异常：

INFO: I/O exception (java.net.SocketException) caught when processing request to {}->http://my.url:80: Connection reset

限制似乎在 200 到 300 个并发连接之间。

我创建了一个简单的应用程序，即使使用该应用程序也能重现该问题：

import java.io.IOException;

import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class App implements Runnable
{
    private static final int NUMBER_THREADS = 1000;

    public static void main( String[] args )
    {
        Thread[] threads = new Thread[NUMBER_THREADS];
        for(int i = 0; i < NUMBER_THREADS; i++)
        {
            threads[i] = new Thread(new App()); 
        }
        for(int i = 0; i < NUMBER_THREADS; i++)
        {
            threads[i].start(); 
        }
    }

    public void run() 
    {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        HttpGet httpget = new HttpGet("http://my.url/test.html");
        CloseableHttpResponse response = null;
        try 
        {
            System.out.println( System.nanoTime() + " " + Thread.currentThread().getName() + " started" );
            response = httpclient.execute(httpget);
            System.out.println( System.nanoTime() + " " + Thread.currentThread().getName() + " finished" );
        } 
        catch (ClientProtocolException e) 
        {
            e.printStackTrace();
        } 
        catch (IOException e) 
        {
            e.printStackTrace();
        } 
        finally 
        {
            try 
            {
                if(response != null)
                {
                    response.close();
                }
            } 
            catch (IOException e) 
            {
                e.printStackTrace();
            }
        }
    }
}

我更新了一些 Mac 设置，但没有任何帮助：

> sysctl -a | grep files
kern.maxfiles = 12288
kern.maxfilesperproc = 10240
kern.maxfiles: 12288
kern.maxfilesperproc: 10240
kern.num_files: 3202
> ulimit -n 10240
> ulimit -n
10240
> sysctl -a | grep somax
kern.ipc.somaxconn: 128
> sudo sysctl -w kern.ipc.somaxconn=2048
Password:
kern.ipc.somaxconn: 128 -> 2048
> sysctl -a | grep somax
kern.ipc.somaxconn: 2048

所以我想了解这个限制来自哪里？ OsX / Apache HttpClient 本身？并且可以控制吗？

提前致谢。

Answer 1

问题确实出在 maxfiles 上，但我没有正确更改它们。 This 文章通过显示在 Mac OS X Yosemite / El Capitan 上更新文件限制的正确程序帮助我解决了这个问题。

1. 创建和更新 /Library/LaunchDaemons/limit.maxfiles.plist 文件：

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
     <plist version="1.0">
       <dict>
         <key>Label</key>
           <string>limit.maxfiles</string>
         <key>ProgramArguments</key>
           <array>
             <string>launchctl</string>
             <string>limit</string>
             <string>maxfiles</string>
             <string>65536</string>
             <string>65536</string>
           </array>
         <key>RunAtLoad</key>
           <true/>
         <key>ServiceIPC</key>
           <false/>
       </dict>
     </plist>
   

2. 创建 /Library/LaunchDaemons/limit.maxproc.plist 文件：

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE plist PUBLIC "-//Apple/DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
     <plist version="1.0">
       <dict>
         <key>Label</key>
           <string>limit.maxproc</string>
         <key>ProgramArguments</key>
           <array>
             <string>launchctl</string>
             <string>limit</string>
             <string>maxproc</string>
             <string>2048</string>
             <string>2048</string>
           </array>
         <key>RunAtLoad</key>
           <true />
         <key>ServiceIPC</key>
           <false />
       </dict>
   

3. 使用以下行添加 .bashprofile：

   ulimit -n 65536
   ulimit -u 2048
   

4. 重启系统