HttpClient Connection reset by peer: socket write error
<p>I used httpclient 4.4 to send get and post request. and i just created a simpile wrapper of httpclient for easy use:</p>

<pre>

    package com.u8.server.sdk;

    import com.sun.net.httpserver.Headers;
    import com.u8.server.log.Log;
    import org.apache.http.Header;
    import org.apache.http.HttpEntity;
    import org.apache.http.HttpResponse;
    import org.apache.http.NameValuePair;
    import org.apache.http.client.ClientProtocolException;
    import org.apache.http.client.HttpClient;
    import org.apache.http.client.HttpRequestRetryHandler;
    import org.apache.http.client.ResponseHandler;
    import org.apache.http.client.config.RequestConfig;
    import org.apache.http.client.entity.UrlEncodedFormEntity;
    import org.apache.http.client.methods.HttpGet;
    import org.apache.http.client.methods.HttpPost;
    import org.apache.http.config.Registry;
    import org.apache.http.config.RegistryBuilder;
    import org.apache.http.conn.socket.ConnectionSocketFactory;
    import org.apache.http.conn.socket.PlainConnectionSocketFactory;
    import org.apache.http.conn.ssl.NoopHostnameVerifier;
    import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
    import org.apache.http.conn.ssl.TrustStrategy;
    import org.apache.http.entity.ByteArrayEntity;
    import org.apache.http.impl.client.BasicCookieStore;
    import org.apache.http.impl.client.CloseableHttpClient;
    import org.apache.http.impl.client.HttpClientBuilder;
    import org.apache.http.impl.client.HttpClients;
    import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
    import org.apache.http.impl.cookie.BasicClientCookie;
    import org.apache.http.message.BasicHeader;
    import org.apache.http.message.BasicNameValuePair;
    import org.apache.http.protocol.HttpContext;
    import org.apache.http.ssl.SSLContextBuilder;
    import org.apache.http.util.EntityUtils;
    import org.springframework.util.StringUtils;

    import javax.net.ssl.HostnameVerifier;
    import javax.net.ssl.SSLContext;
    import java.io.IOException;
    import java.io.UnsupportedEncodingException;
    import java.net.CookiePolicy;
    import java.net.URLEncoder;
    import java.nio.charset.Charset;
    import java.security.cert.CertificateException;
    import java.security.cert.X509Certificate;
    import java.util.ArrayList;
    import java.util.Iterator;
    import java.util.List;
    import java.util.Map;

    /**
     * Created by ant on 2015/10/12.
     */
    public class UHttpAgent {

        private int connectTimeout = 5000;  //5s
        private int socketTimeout = 5000;   //5s
        private int maxTotalConnections = 200; 

        private static UHttpAgent instance;

        private CloseableHttpClient httpClient;

        private UHttpAgent(){

        }

        public static UHttpAgent getInstance(){
            if(instance == null){
                instance = new UHttpAgent();

            }
            return instance;
        }

        public static UHttpAgent newInstance(){
            return new UHttpAgent();
        }


        public String get(String url, Map params){

            return get(url, null, params, "UTF-8");
        }


        public String post(String url, Map params){

            return post(url, null, params, "UTF-8");
        }


        public String get(String url , Map headers, Map params, String encoding){

            if(this.httpClient == null){
                init();
            }

            String fullUrl = url;
            String urlParams = parseGetParams(params, encoding);

            if (urlParams != null)
            {
                if (url.contains("?"))
                {
                    fullUrl = url + "&" + urlParams;
                }
                else
                {
                    fullUrl = url + "?" + urlParams;
                }
            }

            Log.d("the full url is "+ fullUrl);
            HttpGet getReq = new HttpGet(fullUrl.trim());
            getReq.setHeaders(parseHeaders(headers));
            ResponseHandler responseHandler = new ResponseHandler() {
                @Override
                public String handleResponse(HttpResponse httpResponse) throws IOException {
                    HttpEntity entity = httpResponse.getEntity();
                    return entity != null ? EntityUtils.toString(entity) : null;
                }
            };

            try {

                String res = httpClient.execute(getReq, responseHandler);

                return res;

            } catch (Exception e) {
                e.printStackTrace();
            }finally {
                getReq.releaseConnection();
            }

            return null;
        }


        public String post(String url, Map headers, Map params, String encoding){

            List pairs = new ArrayList();
            if(params != null){

                for(String key : params.keySet()){
                    pairs.add(new BasicNameValuePair(key, params.get(key)));
                }
            }

            return post(url, headers, new UrlEncodedFormEntity(pairs, Charset.forName(encoding)));
        }


        public String post(String url, Map headers, HttpEntity entity){

            if(this.httpClient == null) {
                init();
            }

            HttpPost httpPost = new HttpPost(url);
            httpPost.setHeaders(parseHeaders(headers));
            httpPost.setEntity(entity);

            ResponseHandler responseHandler = new ResponseHandler() {
                @Override
                public String handleResponse(HttpResponse httpResponse) throws IOException {
                    HttpEntity entity = httpResponse.getEntity();
                    return entity != null ? EntityUtils.toString(entity) : null;
                }
            };

            try {


                String body = httpClient.execute(httpPost, responseHandler);

                return body;

            } catch (IOException e) {
                e.printStackTrace();
            }finally {
                httpPost.releaseConnection();
            }

            return null;

        }


        private Header[] parseHeaders(Map headers){
            if(null == headers || headers.isEmpty()){
                return getDefaultHeaders();
            }

            Header[] hs = new BasicHeader[headers.size()];
            int i = 0;
            for(String key : headers.keySet()){
                hs[i] = new BasicHeader(key, headers.get(key));
                i++;
            }

            return hs;
        }


        private Header[] getDefaultHeaders(){
            Header[] hs = new BasicHeader[2];
            hs[0] = new BasicHeader("Content-Type", "application/x-www-form-urlencoded");
            hs[1] = new BasicHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.146 Safari/537.36");
            return hs;
        }


        private String parseGetParams(Map data, String encoding){
            if(data == null || data.size()  keyItor = data.keySet().iterator();
            while(keyItor.hasNext()){
                String key = keyItor.next();
                String val = data.get(key);

                try {
                    result.append(key).append("=").append(URLEncoder.encode(val, encoding).replace("+", "%2B")).append("&");
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            }

            return result.deleteCharAt(result.length() - 1).toString();

        }


        private void init(){

            RequestConfig requestConfig = RequestConfig.custom()
                    .setConnectTimeout(connectTimeout)
                    .setSocketTimeout(socketTimeout)
                    .setExpectContinueEnabled(true)
                    .setAuthenticationEnabled(true)
                    .build();

            HttpRequestRetryHandler retryHandler = new HttpRequestRetryHandler() {
                @Override
                public boolean retryRequest(IOException e, int retryNum, HttpContext httpContext) {

                    if(retryNum >= 3){
                        return false;
                    }


                    if(e instanceof org.apache.http.NoHttpResponseException
                            || e instanceof org.apache.http.client.ClientProtocolException
                            || e instanceof java.net.SocketException){

                        return true;
                    }

                    return false;
                }
            };


            try{

                SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {

                    @Override
                    public boolean isTrusted(X509Certificate[] chain, String authType) throws CertificateException {
                        return true;
                    }
                }).build();

                HostnameVerifier hostnameVerifier = NoopHostnameVerifier.INSTANCE;
                SSLConnectionSocketFactory sslFactory = new SSLConnectionSocketFactory(sslContext, hostnameVerifier);

                Registry socketFactoryRegistry = RegistryBuilder.create()
                        .register("http", PlainConnectionSocketFactory.getSocketFactory())
                        .register("https", sslFactory)
                        .build();

                PoolingHttpClientConnectionManager connMgr = new PoolingHttpClientConnectionManager( socketFactoryRegistry);
                connMgr.setMaxTotal(maxTotalConnections);
                connMgr.setDefaultMaxPerRoute((connMgr.getMaxTotal()));

                HttpClientBuilder builder = HttpClients.custom()
                        .setDefaultRequestConfig(requestConfig)
                        .setSslcontext(sslContext)
                        .setConnectionManager(connMgr)
                        .setRetryHandler(retryHandler);

                this.httpClient = builder.build();


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

        }

        public HttpClient getHttpClient(){

            return this.httpClient;
        }

        public void destroy(){

            if(this.httpClient != null){
                try{
                    this.httpClient.close();
                    this.httpClient = null;
                }catch (Exception e){
                    e.printStackTrace();
                }

            }
        }


    }

</pre>

<p>when I use this class to send post request. something strange happened:</p>

<p>the first time, I send a post request to the server, it's ok
after a minutes, I send a same request to the server, it's ok too.
but after a few minutes, I send a same request, something wrong:</p>

<pre>

    java.net.SocketException: Connection reset by peer: socket write error
        at java.net.SocketOutputStream.socketWrite0(Native Method)
        at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:92)
        at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
        at org.apache.http.impl.conn.LoggingOutputStream.write(LoggingOutputStream.java:77)
        at org.apache.http.impl.io.SessionOutputBufferImpl.streamWrite(SessionOutputBufferImpl.java:126)
        at org.apache.http.impl.io.SessionOutputBufferImpl.flushBuffer(SessionOutputBufferImpl.java:138)
        at org.apache.http.impl.io.SessionOutputBufferImpl.flush(SessionOutputBufferImpl.java:146)
        at org.apache.http.impl.BHttpConnectionBase.doFlush(BHttpConnectionBase.java:175)
        at org.apache.http.impl.DefaultBHttpClientConnection.flush(DefaultBHttpClientConnection.java:185)
        at org.apache.http.impl.conn.CPoolProxy.flush(CPoolProxy.java:177)
        at org.apache.http.protocol.HttpRequestExecutor.doSendRequest(HttpRequestExecutor.java:215)
        at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:122)
        at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:271)
        at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)
        at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)
        at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
        at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:71)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:220)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:164)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:139)
        at com.u8.server.sdk.UHttpAgent.post(UHttpAgent.java:259)
        at com.u8.server.sdk.UHttpAgent.post(UHttpAgent.java:147)
        at com.u8.server.sdk.baidu.BaiduSDK.verify(BaiduSDK.java:30)
        at com.u8.server.web.UserAction.getLoginToken(UserAction.java:100)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)

</pre>

<p>but then , I still send a same request to the server, it's ok again.</p>

<p>Every time I tried according to the above steps, The same thing happened.</p>

<p>Anyone can help me ? Thanks a lot.</p>