node.js sockets.io每隔约25秒断开连接(与心跳相关)

这是我的服务器代码：

var io = require('socket.io').listen(5876);
io.sockets.on('connection',function (socket)
{
    console.log("New connection established");

    socket.on('disconnect',function()
    {
        console.log("A client has disconnected.");
    });
}

我的客户端使用socket.io.js分发进行连接.据我所知(显然不正确),我需要我的客户端每15秒发送一次“心跳”(“:: 2”的消息),以防止服务器认为连接已死并断开连接.基本上：

<script src="socket.io.js"></script>
<script>
    var socket = io.connect('http://localhost:5876');

    socket.on('connect',function(data)
    {
        console.log("Connected to server.");
        seTinterval(function() { socket.emit("::2"); console.log("sent heartbeat"); },15000); // schedule a heartbeat for every 15 seconds
    });
</script>

但是客户端仍然每25秒重新连接一次(不包括前25秒).

node.js服务器控制台日志看起来像这样(可能已经删除了一些早期相同的连接/断开阶段,因为它每25秒回显一次)：

New connection established
   debug - emitTing heartbeat for client 652791160849839915
   debug - websocket wriTing 2::
   debug - set heartbeat timeout for client 652791160849839915
   debug - got heartbeat packet
   debug - cleared heartbeat timeout for client 652791160849839915
   debug - set heartbeat interval for client 652791160849839915
   info  - transport end
   debug - set close timeout for client 652791160849839915
   debug - cleared close timeout for client 652791160849839915
   debug - cleared heartbeat interval for client 652791160849839915
A client has disconnected.
   debug - discarding transport
   debug - client authorized
   info  - handshake authorized 5961067041159055274
   debug - setTing request GET /socket.io/1/websocket/5961067041159055274
   debug - set heartbeat interval for client 5961067041159055274
   debug - client authorized for
   debug - websocket wriTing 1::
New connection established

如何阻止我的服务器每隔25秒断开重新连接客户端的连接？