Mac上的Apache HttpClient 4.5出现“连接重置”异常

Question

I need to get up to 1000 threads to send HTTP request simultaneously. Yet it seems on Mac I am hitting some limit, which causes Apache HTTPClient to return exception:

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

The limit appears to be somewhere between 200 and 300 concurrent connections.

I created a simple app and able to reproduce the issue even with that app:

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();
            }
        }
    }
}

I updated some Mac settings, but that didn't help anything:

> 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

So I want to understand where this limit is coming from? OsX / Apache HttpClient itself? And is it possible to control it?

Thanks in advance.

Answer 1

The problem was indeed with maxfiles, but I was not changing them right. This article helped me to solve it by showing the correct procedure for updating file limits on Mac OS X Yosemite / El Capitan.

1. Create and update /Library/LaunchDaemons/limit.maxfiles.plist file:

    <?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. Create /Library/LaunchDaemons/limit.maxproc.plist file:

    <?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. Add .bashprofile with the following lines:

    ulimit -n 65536 ulimit -u 2048 

4. Restart your system