IE memory leak, how to resolve?

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  • rizwan6feb
    New Member
    • Jul 2007
    • 108
    #1

    IE memory leak, how to resolve?

    I am working on an ajax chat application, done most of the work but when i tested it on IE (both on IE6 and IE7), found that there is a memory leak. The application works fine on FF. How can i fix this?

    I have used ajax in the following way (this is a similar to how i am using ajax in my chat application); incrementer.php file on line # 34 simply prints an incremented value from the session

    Code:
    <html>
<head>
<script language="javascript">
	function getAjaxObject(){
		try{
			ajaxRequest = new XMLHttpRequest();
		} catch (e){
			// Internet Explorer Browsers
			try{
				ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (e) {
				try{
					ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e){
					// Something went wrong
					alert("Your browser doesn't support ajax!");
					return false;
				}
			}
		}
		return ajaxRequest;	
	}
	function startCounting(){
		var a=getAjaxObject();
		a.onreadystatechange = function(){
			if(a.readyState==4){
				var text=a.responseText;
				var e=document.getElementById('val');
				if(e){
					e.innerHTML=text;
				}
			}
		}
		a.open("GET", "incrementer.php", true);
		a.send(null);
		setTimeout(startCounting,1);
	}
</script>
</head>

<body>
	<input type="button" value="Send Object" onclick="startCounting()" />
	<div id="val">	</div>
</body>
</html>
    Tags: None
    • acoder
      Recognized Expert MVP
      • Nov 2006
      • 16032
      #2
      1 millisecond is a bit too small, isn't it?

      Try using something like IEDrip to detect the leak. It is often caused by circular references, particularly closures - see link.

        Comment

        • rizwan6feb
          New Member
          • Jul 2007
          • 108
          #3
          Originally posted by acoder
          1 millisecond is a bit too small, isn't it?

          Try using something like IEDrip to detect the leak. It is often caused by circular references, particularly closures - see link.
          Thanks for your reply. Setting the interval to 1 millisecond i can see quick increase in the use of memory.

          I am unable to trace circular reference in my code. If there is any, please point to that & and how can i resolve this

            Comment

            • rizwan6feb
              New Member
              • Jul 2007
              • 108
              #4
              I have found a solution which leads to another problem. The solution is given below, i have got rid of inner function (see line # 38 ). Now there is an error at line# 28 as i have no access to variable 'a' within updateText The problem is how can i access variable 'a' in the updateText function.
              Code:
              <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<script language="javascript">
	var x=0;
	function getAjaxObject(){
		try{
			ajaxRequest = new XMLHttpRequest();
		} catch (e){
			// Internet Explorer Browsers
			try{
				ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (e) {
				try{
					ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e){
					// Something went wrong
					alert("Your browser doesn't support ajax!");
					return false;
				}
			}
		}
		return ajaxRequest;	
	}
	function updateText(){
		if(a.readyState==4){
			var text=a.responseText;
			var e=document.getElementById('val');
			if(e){
				e.innerHTML=text;
			}
		}
	}
	function startCounting(){
		var a=getAjaxObject();
		a.onreadystatechange = updateText;
		a.open("GET", "incrementer.php", true);
		a.send(null);
		setTimeout(startCounting,1);
	}
</script>
</head>

<body>
	<input type="button" value="Send Object" onclick="startCounting()" />
	<div id="val">	</div>
</body>
</html>

                Comment

                • acoder
                  Recognized Expert MVP
                  • Nov 2006
                  • 16032
                  #5
                  One solution is to make 'a' global. If you don't want to do that, you can use a closure.

                    Comment

                    • rizwan6feb
                      New Member
                      • Jul 2007
                      • 108
                      #6
                      Originally posted by acoder
                      One solution is to make 'a' global. If you don't want to do that, you can use a closure.
                      I can't use global variable and i have no idea how to use a closure. Please give me sample code

                        Comment

                        • acoder
                          Recognized Expert MVP
                          • Nov 2006
                          • 16032
                          #7
                          Basically creating a function which returns a function, e.g.
                          [code=javascript]function updateText2(a) {
                          return function() {
                          updateText(a);
                          }
                          }[/code] and calling that instead. See this link for an explanation of closures.

                            Comment

                            • rizwan6feb
                              New Member
                              • Jul 2007
                              • 108
                              #8
                              I have used closure, but the problem persists. Please see the code below what i am doing wrong
                              Code:
                              <html>
<head>
<script language="javascript">
	var x=0;
	function getAjaxObject(){
		try{
			ajaxRequest = new XMLHttpRequest();
		} catch (e){
			// Internet Explorer Browsers
			try{
				ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (e) {
				try{
					ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e){
					// Something went wrong
					alert("Your browser doesn't support ajax!");
					return false;
				}
			}
		}
		return ajaxRequest;	
	}
	function updateText(a){
		return function(){
			if(a.readyState==4){
				var text=a.responseText;
				var e=document.getElementById('val');
				if(e){
					e.innerHTML=text;
				}
			}
		};
	}
	function startCounting(){
		var a=getAjaxObject();
		var fun1=updateText(a);
		a.onreadystatechange = fun1;
		a.open("GET", "incrementer.php", true);
		a.send(null);
		setTimeout(startCounting,1);
	}
</script>
</head>

<body>
	<input type="button" value="Start Counting" onclick="startCounting()" />
	<div id="val">	</div>
</body>
</html>

                                Comment

                                • rnd me
                                  Recognized Expert Contributor
                                  • Jun 2007
                                  • 427
                                  #9
                                  Code:
                                  	function startCounting(){
		var a=getAjaxObject();
		a.onreadystatechange = function(){
			if(a.readyState==4){
				var text=a.responseText;
				var e=document.getElementById('val');
				if(e){
					e.innerHTML=text;
				}
				[U][B]a = null;[/B][/U]
			}
		}
		a.open("GET", "incrementer.php", true);
		a.send(null);
		setTimeout(startCounting,1);
	}

                                    Comment

                                    • rizwan6feb
                                      New Member
                                      • Jul 2007
                                      • 108
                                      #10
                                      Yes, that works. Great job man, thank you very much

                                        Comment

                                        • acoder
                                          Recognized Expert MVP
                                          • Nov 2006
                                          • 16032
                                          #11
                                          So simple that I didn't think of. Thanks rnd me ;)

                                            Comment

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