新手求助！！httpclient连接超时

[hhg0719]

先上错误：

org.apache.http.conn.HttpHostConnectException: Connection to http://121.xx.xxx.116:8082 refused
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:190)
    at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:294)
    at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:640)
    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)
    at com.cfwx.multichannel.jinjv.http.GetRespFromJinJv.getResp(GetResp.java:90)
    at com.cfwx.multichannel.jinjv.test.MainTest.main(MainTest.java:26)
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
    at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
    at java.net.Socket.connect(Socket.java:529)
    at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:127)
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)
    ... 8 more

实现代码（主要部分）：

HttpPost httpPost = new HttpPost(Url);
    httpPost.setEntity(formEntiry);
         
    HttpResponse httpResponse = null;
    HttpClient httpClient = new DefaultHttpClient();
    httpClient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT,30000);
    httpClient.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT,30000);
    try {
        httpResponse = httpClient.execute(httpPost);
    } catch (ClientProtocolException e) {
        logger.error("ClientProtocolException!", e);
    } catch (IOException e) {
        logger.error("IOException!", e);
    }

是这样的，在发200次请求内，都是可以得到返回结果的，但是往200次后，会出现连接超时的错误。
这是什么原因，服务器那边也没有做任何限制。
各位大神帮忙解答一下

[tony4geek]

设值时间长点吧。

[执笔记忆的空白]

你这个超时了啊，请求时间弄长点

[zhuangqingch]

执行httpClient.execute(httpPost)会最终会调用JDK自己的API，即调用java.net.DualStackPlainSocketImpl这个类的waitForConnect方法。该方法是一个native方法，具体由C语言实现，通过查看对应的C语言源代码DualStackPlainSocketImpl.c文件，可以看到具体实现如下：

/*
 * Class:     java_net_DualStackPlainSocketImpl
 * Method:    waitForConnect
 * Signature: (II)V
 */
JNIEXPORT void JNICALL Java_java_net_DualStackPlainSocketImpl_waitForConnect
  (JNIEnv *env, jclass clazz, jint fd, jint timeout) {
    int rv, retry;
    int optlen = sizeof(rv);
    fd_set wr, ex;
    struct timeval t;

    FD_ZERO(&wr);
    FD_ZERO(&ex);
    FD_SET(fd, &wr);
    FD_SET(fd, &ex);
    t.tv_sec = timeout / 1000;
    t.tv_usec = (timeout % 1000) * 1000;

    /*
     * Wait for timeout, connection established or
     * connection failed.
     */
    rv = select(fd+1, 0, &wr, &ex, &t);

    /*
     * Timeout before connection is established/failed so
     * we throw exception and shutdown input/output to prevent
     * socket from being used.
     * The socket should be closed immediately by the caller.
     */
    if (rv == 0) {
        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketTimeoutException",
                        "connect timed out");
        shutdown( fd, SD_BOTH );
        return;
    }

    /*
     * Socket is writable or error occured. On some Windows editions
     * the socket will appear writable when the connect fails so we
     * check for error rather than writable.
     */
    if (!FD_ISSET(fd, &ex)) {
        return;         /* connection established */
    }

    /*
     * Connection failed. The logic here is designed to work around
     * bug on Windows NT whereby using getsockopt to obtain the
     * last error (SO_ERROR) indicates there is no error. The workaround
     * on NT is to allow winsock to be scheduled and this is done by
     * yielding and retrying. As yielding is problematic in heavy
     * load conditions we attempt up to 3 times to get the error reason.
     */
    for (retry=0; retry<3; retry++) {
        NET_GetSockOpt(fd, SOL_SOCKET, SO_ERROR,
                       (char*)&rv, &optlen);
        if (rv) {
            break;
        }
        Sleep(0);
    }

    if (rv == 0) {
        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException",
                        "Unable to establish connection");
    } else {
        NET_ThrowNew(env, rv, "connect");
    }
}

通过代码，可以看出存在2种可能出现的异常：
1、SocketTimeoutException
2、SocketException
第1种异常是发送在建立连接阶段，如连接服务器114.xx.xx.xx:8088，首先会进行与IP地址114.xx.xx.xx建立连接，如果连接失败则会抛SocketTimeoutException异常
第2种异常当建立好连接后，会与服务器的目标端口建立连接，如与端口8088建立连接，当服务器不存在8088这个端口或者该端口的连接数已满时，则会抛出ConnectException(SocketException的子类）异常

所以通过上述分析和代码描述的现象以及抛出的异常信息（前200次正常，超过200失败，异常为ConnectException），楼主的代码是出现了端口连接数已满的问题。端口连接数问题，这个是操作系统本身的硬性限制。限制数根据不同系统而不同。
楼主如果想解决这个问题，可以先查看下是用了什么服务器，通过服务器是可以配置连接数大小的。关于端口连接数限制问题，建立楼主网上查找多了解下。另外1楼和2楼说的设置超时时间，当前楼主的代码不是这个原因导致的，30秒够长了，这里提醒下楼主，如果是超时，则异常会是ConnectTimeoutException（SocketException子类）
希望这些分析能对你有所帮助，如有疑问，欢迎追问。
下面是楼主代码异常栈的调用过程：

[zhuangqingch]

/*
 * Class:     java_net_DualStackPlainSocketImpl
 * Method:    waitForConnect
 * Signature: (II)V
 */
JNIEXPORT void JNICALL Java_java_net_DualStackPlainSocketImpl_waitForConnect
  (JNIEnv *env, jclass clazz, jint fd, jint timeout) {
    int rv, retry;
    int optlen = sizeof(rv);
    fd_set wr, ex;
    struct timeval t;
 
    FD_ZERO(&wr);
    FD_ZERO(&ex);
    FD_SET(fd, &wr);
    FD_SET(fd, &ex);
    t.tv_sec = timeout / 1000;
    t.tv_usec = (timeout % 1000) * 1000;
 
    /*
     * Wait for timeout, connection established or
     * connection failed.
     */
    rv = select(fd+1, 0, &wr, &ex, &t);
 
    /*
     * Timeout before connection is established/failed so
     * we throw exception and shutdown input/output to prevent
     * socket from being used.
     * The socket should be closed immediately by the caller.
     */
    if (rv == 0) {
        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketTimeoutException",
                        "connect timed out");
        shutdown( fd, SD_BOTH );
        return;
    }
 
    /*
     * Socket is writable or error occured. On some Windows editions
     * the socket will appear writable when the connect fails so we
     * check for error rather than writable.
     */
    if (!FD_ISSET(fd, &ex)) {
        return;         /* connection established */
    }
 
    /*
     * Connection failed. The logic here is designed to work around
     * bug on Windows NT whereby using getsockopt to obtain the
     * last error (SO_ERROR) indicates there is no error. The workaround
     * on NT is to allow winsock to be scheduled and this is done by
     * yielding and retrying. As yielding is problematic in heavy
     * load conditions we attempt up to 3 times to get the error reason.
     */
    for (retry=0; retry<3; retry++) {
        NET_GetSockOpt(fd, SOL_SOCKET, SO_ERROR,
                       (char*)&rv, &optlen);
        if (rv) {
            break;
        }
        Sleep(0);
    }
 
    if (rv == 0) {
        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException",
                        "Unable to establish connection");
    } else {
        NET_ThrowNew(env, rv, "connect");
    }
}

[zhuangqingch]

不好意思，“另外1楼和2楼说的设置超时时间，当前楼主的代码不是这个原因导致的，30秒够长了，这里提醒下楼主，如果是超时，则异常会是ConnectTimeoutException（SocketException子类）”描述有误，超时是发生在建立连接阶段，如果超时是抛出SocketTimeoutException 关于网络连接异常，楼主可以看下JDK API，通过异常描述可以大概猜测一些代码问题的产生原因： java.net.SocketTimeoutException（无子类）java.net.SocketException（子类：BindException, ConnectException, NoRouteToHostException, PortUnreachableException ）

[hhg0719]

引用 5 楼 zhuangqingch 的回复:

不好意思，“另外1楼和2楼说的设置超时时间，当前楼主的代码不是这个原因导致的，30秒够长了，这里提醒下楼主，如果是超时，则异常会是ConnectTimeoutException（SocketException子类）”描述有误，超时是发生在建立连接阶段，如果超时是抛出SocketTimeoutException 关于网络连接异常，楼主可以看下JDK API，通过异常描述可以大概猜测一些代码问题的产生原因： java.net.SocketTimeoutException（无子类）java.net.SocketException（子类：BindException, ConnectException, NoRouteToHostException, PortUnreachableException ）

大神分析的很透彻，真是让小弟收益匪浅。 原因是链接数的问题，查了相关资料，如果不手动释放链接数，得在180s后才会自动释放。 我在代码中手动断开链接，连续发1000次请求都不会报超时的错误。 感谢大神的解答