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POWhy this code is consuming memory and it is not get fully reclaimed?
 

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  1. POWhy this code is consuming memory and it is not get fully reclaimed?
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    <p>I has a simple JavaScript code which is consuming memory while running infinitely. Memory consumption is monitored by Google Chrome internal memory profiler.</p> <pre><code> setInterval(function(){ var xhr = new XMLHttpRequest(); xhr.open('GET', 'json.txt', true); xhr.onreadystatechange = function() { if(this.readyState == 4 &amp;&amp; this.status == 200) { console.log(this.responseText); } }; xhr.send(''); }, 500); </code></pre> <p>Html file with above code sample and <code>json.txt</code> is hosted on on my local server, getting a file isn't taking more than 500ms (it is always about 7-10ms).</p> <p>In a long time run the memory graph is looks like that <img src="https://i.stack.imgur.com/l7O7w.png" alt="Initial memory consumption graph"></p> <p><strong>EDIT</strong> The same Chrome window after a hour of work <img src="https://i.stack.imgur.com/tp50g.png" alt="Graph after a hour of work"></p> <p><strong>EDIT</strong> On the long run (hours) not all memory is reclaimed an graph is still ascending. I understand <strong>why</strong> the memory is consumed, i didn't understand why it is <strong>not fully reclaimed</strong>.</p> <p><strong>EDIT</strong> This is how i can reduce memory leak</p> <pre><code> var callback = function(){ if(this.readyState == 4 &amp;&amp; this.status == 200) { console.log(this.responseText); } } setInterval(function(){ var xhr = new XMLHttpRequest(); xhr.open('GET', 'json.txt', true); xhr.onreadystatechange = callback; xhr.send(''); }, 500); </code></pre> <p>This improvement allowing not to link callback's closure to <code>xhr</code> var. </p>
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      1. POWhy this code is consuming memory and it is not get fully reclaimed?
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    1. COwere you able to fix your leak with the accepted answer?
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      1. POWhy this code is consuming memory and it is not get fully reclaimed?
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    2. CO@brainjam, the accpeted answer gives me the clue, how this code can be improved. See my edit.
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      1. POWhy this code is consuming memory and it is not get fully reclaimed?
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    3. COmy brain hurts. I guess your original construction was creating a circular reference between the anonymous function and the closure. This is a very good example of a very subtle (to me anyways) memory leak pattern. Thanks for persisting until you got a good answer.
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