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IE memory leak, how to resolve?

rizwan6feb's Avatar
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Join Date: Jul 2007
Posts: 106
#1: Sep 5 '08
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

Expand|Select|Wrap|Line Numbers
  1. <html>
  2. <head>
  3. <script language="javascript">
  4.     function getAjaxObject(){
  5.         try{
  6.             ajaxRequest = new XMLHttpRequest();
  7.         } catch (e){
  8.             // Internet Explorer Browsers
  9.             try{
  10.                 ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
  11.             } catch (e) {
  12.                 try{
  13.                     ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
  14.                 } catch (e){
  15.                     // Something went wrong
  16.                     alert("Your browser doesn't support ajax!");
  17.                     return false;
  18.                 }
  19.             }
  20.         }
  21.         return ajaxRequest;    
  22.     }
  23.     function startCounting(){
  24.         var a=getAjaxObject();
  25.         a.onreadystatechange = function(){
  26.             if(a.readyState==4){
  27.                 var text=a.responseText;
  28.                 var e=document.getElementById('val');
  29.                 if(e){
  30.                     e.innerHTML=text;
  31.                 }
  32.             }
  33.         }
  34.         a.open("GET", "incrementer.php", true);
  35.         a.send(null);
  36.         setTimeout(startCounting,1);
  37.     }
  38. </script>
  39. </head>
  40.  
  41. <body>
  42.     <input type="button" value="Send Object" onclick="startCounting()" />
  43.     <div id="val">    </div>
  44. </body>
  45. </html>
  46.  
  47.  

acoder's Avatar
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Location: UK
Posts: 14,581
#2: Sep 5 '08

re: IE memory leak, how to resolve?

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.
rizwan6feb's Avatar
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Join Date: Jul 2007
Posts: 106
#3: Sep 6 '08

re: IE memory leak, how to resolve?

Quote:

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
rizwan6feb's Avatar
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Join Date: Jul 2007
Posts: 106
#4: Sep 6 '08

re: IE memory leak, how to resolve?

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.
Expand|Select|Wrap|Line Numbers
  1. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  2. <html xmlns="http://www.w3.org/1999/xhtml">
  3. <head>
  4. <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  5. <title>Untitled Document</title>
  6. <script language="javascript">
  7.     var x=0;
  8.     function getAjaxObject(){
  9.         try{
  10.             ajaxRequest = new XMLHttpRequest();
  11.         } catch (e){
  12.             // Internet Explorer Browsers
  13.             try{
  14.                 ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
  15.             } catch (e) {
  16.                 try{
  17.                     ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
  18.                 } catch (e){
  19.                     // Something went wrong
  20.                     alert("Your browser doesn't support ajax!");
  21.                     return false;
  22.                 }
  23.             }
  24.         }
  25.         return ajaxRequest;    
  26.     }
  27.     function updateText(){
  28.         if(a.readyState==4){
  29.             var text=a.responseText;
  30.             var e=document.getElementById('val');
  31.             if(e){
  32.                 e.innerHTML=text;
  33.             }
  34.         }
  35.     }
  36.     function startCounting(){
  37.         var a=getAjaxObject();
  38.         a.onreadystatechange = updateText;
  39.         a.open("GET", "incrementer.php", true);
  40.         a.send(null);
  41.         setTimeout(startCounting,1);
  42.     }
  43. </script>
  44. </head>
  45.  
  46. <body>
  47.     <input type="button" value="Send Object" onclick="startCounting()" />
  48.     <div id="val">    </div>
  49. </body>
  50. </html>
  51.  
  52.  
acoder's Avatar
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Location: UK
Posts: 14,581
#5: Sep 6 '08

re: IE memory leak, how to resolve?

One solution is to make 'a' global. If you don't want to do that, you can use a closure.
rizwan6feb's Avatar
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Join Date: Jul 2007
Posts: 106
#6: Sep 7 '08

re: IE memory leak, how to resolve?

Quote:

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
acoder's Avatar
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#7: Sep 7 '08

re: IE memory leak, how to resolve?

Basically creating a function which returns a function, e.g.
Expand|Select|Wrap|Line Numbers
  1. function updateText2(a) {
  2.     return function() {
  3.         updateText(a);
  4.     }
  5. }
and calling that instead. See this link for an explanation of closures.
rizwan6feb's Avatar
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Join Date: Jul 2007
Posts: 106
#8: Sep 8 '08

re: IE memory leak, how to resolve?

I have used closure, but the problem persists. Please see the code below what i am doing wrong
Expand|Select|Wrap|Line Numbers
  1. <html>
  2. <head>
  3. <script language="javascript">
  4.     var x=0;
  5.     function getAjaxObject(){
  6.         try{
  7.             ajaxRequest = new XMLHttpRequest();
  8.         } catch (e){
  9.             // Internet Explorer Browsers
  10.             try{
  11.                 ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
  12.             } catch (e) {
  13.                 try{
  14.                     ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
  15.                 } catch (e){
  16.                     // Something went wrong
  17.                     alert("Your browser doesn't support ajax!");
  18.                     return false;
  19.                 }
  20.             }
  21.         }
  22.         return ajaxRequest;    
  23.     }
  24.     function updateText(a){
  25.         return function(){
  26.             if(a.readyState==4){
  27.                 var text=a.responseText;
  28.                 var e=document.getElementById('val');
  29.                 if(e){
  30.                     e.innerHTML=text;
  31.                 }
  32.             }
  33.         };
  34.     }
  35.     function startCounting(){
  36.         var a=getAjaxObject();
  37.         var fun1=updateText(a);
  38.         a.onreadystatechange = fun1;
  39.         a.open("GET", "incrementer.php", true);
  40.         a.send(null);
  41.         setTimeout(startCounting,1);
  42.     }
  43. </script>
  44. </head>
  45.  
  46. <body>
  47.     <input type="button" value="Start Counting" onclick="startCounting()" />
  48.     <div id="val">    </div>
  49. </body>
  50. </html>
  51.  
rnd me's Avatar
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Location: Urbana IL
Posts: 411
#9: Sep 8 '08

re: IE memory leak, how to resolve?

Expand|Select|Wrap|Line Numbers
  1.  
  2.     function startCounting(){
  3.         var a=getAjaxObject();
  4.         a.onreadystatechange = function(){
  5.             if(a.readyState==4){
  6.                 var text=a.responseText;
  7.                 var e=document.getElementById('val');
  8.                 if(e){
  9.                     e.innerHTML=text;
  10.                 }
  11.                 a = null;
  12.             }
  13.         }
  14.         a.open("GET", "incrementer.php", true);
  15.         a.send(null);
  16.         setTimeout(startCounting,1);
  17.     }
  18.  
rizwan6feb's Avatar
Member
  
Join Date: Jul 2007
Posts: 106
#10: Sep 8 '08

re: IE memory leak, how to resolve?

Yes, that works. Great job man, thank you very much
acoder's Avatar
Site Moderator
  
Join Date: Nov 2006
Location: UK
Posts: 14,581
#11: Sep 8 '08

re: IE memory leak, how to resolve?

So simple that I didn't think of. Thanks rnd me ;)
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