EDIT

$(document).ready(function(){

  function updateMemoryStatus() {

     $.getJSON(

        "MemoryService.jsp",

        function(data){

          $("#status").html(''); // make empty

          $("#status").html('<div>CPU Cores: ' + data.availableProcessors + '</div>'); // make empty

          $("#status").append(memoryUsageEntry(data.heapMemoryUsage, data.recommendedMinimumHeap, "HeapUsage", "100%", "#F48B65", "#65B1F4"));

          if(data.permGenSpaceUsage){

              $("#status").append(memoryUsageEntry(data.permGenSpaceUsage, data.recommendedMinimumPermGenSpace, "PermGenSpaceUsage", "100%","#F48B65", "#65B1F4"));              

          }

     }); // end JSON

    setTimeout(function(){

        updateMemoryStatus()

        }, 1000);

  } // end updateMemory

  function memoryUsageEntry(memoryUsage, recommended, label, barWidth, cssColorUsed, cssColorMax){

    var mb = 1024 * 1024;

    var gb = mb * 1024;

    var max = memoryUsage.max ? memoryUsage.max / mb : -1;

    var used = memoryUsage.used / mb;

    var percent = used * 100 / max;

    var recommendedMB = recommended / mb;

    var html = '';

    html += '<span class="memory-usage">';

    html += label + '(' + used 

    if(recommendedMB > 0){

        html += ' of '  + max+ ' MB, recommended: '  + recommendedMB 

    }

    html += ' MB) ';

    html += '<div style="height: 100%; width:' + barWidth + ';background-color:' + cssColorMax + '">';

    html += '<div style="background-color:' + cssColorUsed + '; width:' + percent + '%">&nbsp;</div></div></span>';

    return html;

  }

  updateMemoryStatus()

});