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POHow to track any object creation in Java since freeMemory() only reports long-lived objects?
 

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  1. POHow to track any object creation in Java since freeMemory() only reports long-lived objects?
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    <p>Whenever a new object is created by my JVM I want to print something in the log. I was trying to detect that using Runtime.getRuntime().freeMemory() but unfortunately it does NOT take into account any short-lived object until it is promoted to the heap (<a href="https://stackoverflow.com/questions/9809920/how-to-track-any-object-instantiation-on-my-jvm-with-runtime-freememory-and-gc">check here for more details</a>).</p> <p>So does anyone know how to detect/track whenever an object is instantiated/created by my JVM? To make it easier, how do we complete the code below:</p> <p><strong>Feel free to use MemoryPoolMXBean and JMX:</strong></p> <pre><code>public class MemoryUtils { private static Set&lt;String&gt; set = new HashSet&lt;String&gt;(); public static void main(String[] args) { // START // now create a bunch of objects and save them in the set for (int i = 0; i &lt; 100; i++) { set.add(new String("foo" + i)); } // FINISH // FIXME: Do something here to detect that a bunch of objects were created! } } </code></pre> <p><strong>Edit:</strong> Trying solution proposed by Vladimir below:</p> <p>It works, but with a weird side-effect:</p> <pre><code>long t = totalThreadMemoryAllocated(); // did nothing t = totalThreadMemoryAllocated() - t; System.out.println(t); // ==&gt; 48 !!!??? public static long totalThreadMemoryAllocated() { com.sun.management.ThreadMXBean tBean = (com.sun.management.ThreadMXBean) ManagementFactory.getThreadMXBean(); return tBean.getThreadAllocatedBytes(Thread.currentThread().getId()); } </code></pre> <p>But it DOES account for any object creation so I guess I could use this if I subtract the magic number 48 from it.</p>
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    1. COIs using AspectJ an option? If so, this question probably contains code that can be modified so that the aspect triggers on any invocation of a constructor: http://stackoverflow.com/questions/6402304/help-with-pointcut-aspectj
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    2. COThanks @Joe23, but I am looking for a more pure java solution. I think using JMX to access all the memory pools and adding the memory used might be the solution so when my total increases I can assume I had objects created somewhere (also assuming GC did not trigger)
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    3. COI think you have a poor understanding of how Java heap works. Outside of a (slow) debug environment there's no way to do what you want.
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