I write a java client which connect to the scanner scan and get the status of scanner using rest api. But when the client run
several hours, the server become very very slow. Please help me check the code and tell me what's the problem.

  StringBuilder data = new StringBuilder();
  data.append("{ \"url\": \"");
  data.append(url);
  data.append("\",\"checks\": [\"*\"]");
     data.append("}");

     DefaultHttpClient client = null;
     try {
   client = new DefaultHttpClient();
   client.getParams().setParameter("Content-Type", "UTF-8");
   
   HttpPost addPost = new HttpPost(serverurl);
   addPost.setEntity( new StringEntity(data.toString()));
   HttpResponse response = client.execute(addPost);
   
   if (response.getStatusLine().getStatusCode() == 200) {
    StringBuilder sb = new StringBuilder();
    BufferedReader br = null;
    try {
     br = new BufferedReader(new InputStreamReader((response.getEntity().getContent())));
     String s ;
     while ((s = br.readLine()) != null) {
                  sb.append(s);
              }
    }
    catch (IOException e) {
     if (br != null) { br.close(); }
    }
    
    if (sb.length() > 0) {
     String taskid = null;
     Matcher match = pattern.matcher(sb.toString());
     while (match.find()) {
      String s = match.group().replaceAll("\"", "");
      if ("id".equals(s)) continue ;
      taskid = s;
     }
     if (taskid == null) {
      throw new Exception("taskid is null");
     }
     
     String status = null;
     while (true) {
      HttpGet get = new HttpGet(serverurl+"/"+taskid);
      HttpResponse queryResponse = client.execute(get);
      if (queryResponse.getStatusLine().getStatusCode() == 200) {
       sb.setLength(0);
       br = new BufferedReader(new InputStreamReader((queryResponse.getEntity().getContent()), "UTF-8"));
       String json;
       while ((json = br.readLine()) != null) {
        sb.append(json);
       }
       
       HashMap<String, Object> obj;
       try {
         obj = (HashMap<String, Object>) JSONUtil.deserialize(sb.toString());
       }
       catch (Exception e) {
        System.out.println(sb.toString());
        throw e ;
       }
       

       status = (String) obj.get("status");
       System.out.println(sdf.format(new Date())+", taskid=" + taskid + ", status="+ status);
       if ("done".equals(status)) {
        break ;
       }
       Thread.sleep(cycle * 1000);
      }
     }
     
     if ("done".equals(status)) {
      HttpResponse reportResponse = client.execute(new HttpGet(serverurl+"/"+taskid+"/report"));
      if (reportResponse.getStatusLine().getStatusCode() == 200) {
       sb.setLength(0);
       br = new BufferedReader(new InputStreamReader((reportResponse.getEntity().getContent())));
       String json;
       while ((json = br.readLine()) != null) {
        sb.append(json);
       }
//       System.out.println(sb.toString());
      }
     }