我有两个服务器与HTTP通信：查看部分客户端代码

 PostMethod postMethod = new PostMethod(strURL);
    int bodylength=UCIPBodyRequestGen.toStringBodyRequest(_request, DEFAULT_CHARSET).length();
    setRequestHeader(postMethod,bodylength);
    postMethod.setRequestBody(requestBody);
    HttpClient myClient = new HttpClient();
    myClient.setConnectionTimeout(mcf.getTimeout());
    myClient.setTimeout(mcf.getTimeout());
   int statusCode = myClient.executeMethod(postMethod);
   responseBody=postMethod.getResponseBodyAsString();

我在一些请求~500ms中有一点延迟，另一个平均值是~20ms

TCPDUMP show that the delay is in TCP FIN-ACK

2014-12-23 09:38:59.069230  HTTP/XML    1534    POST /Servlet HTTP/1.1 
2014-12-23 09:38:59.070450  HTTP    514 HTTP/1.1 200 OK 
2014-12-23 09:38:59.110758  TCP 66  14783?9770 [ACK] Seq=1469 Ack=450 Win=33920 Len=0 TSval=2321949059 TSecr=2321949019
2014-12-23 09:38:59.602623  TCP 66  14783?9770 [FIN, ACK] Seq=1469 Ack=450 Win=33920 Len=0 TSval=2321949551 TSecr=2321949019

关于这次延误有什么线索吗？