We will take a look at a memory leak and investigate how it would be possible to detect using the tools that JProfiler offers. There are many blog posts and articles about different kind of memory leaks and how their memory footprint looks like, unfortunately, it is very hard to find the memory leak based only on the memory graph. JProfiler brings many more features, like database profiling but these are out of the scope of this blog post. It provides many useful tools such as memory profiling, a way to analyze heap snapshots and a live memory view that shows all objects that are currently in use. One of the most common scenarios for memory leak is referencing a heavy collection of elements as a static field.JProfiler is a java profiler developed by ej-technologies that helps developers resolve performance bottlenecks, find memory leaks and understand threading issues. To reproduce memory leak faster and only for example I will lower the heap size to 125MB using JVM argument -Xmx125m To enable G1 GC use -XX:+UseG1GCJVM argument. It uses techniques to separate Heap memory into regions and does object collection in parallel. G1 Garbage Collector is used for a large heap area.To enable CMS Garbage Collector use -XX:UseConcMarkSweepGC JVM argument. CMS Garbage Collector or Concurrent Mark Sweep Garbage Collector uses multiple threads to collect unreferenced objects and it is designed for application that prefer shortened GC pauses.
#JPROFILER MEMORY LEAK SERIAL#
Phantom Reference - Object referenced using are not automatically cleaned by GC, it needs to be cleaned up manually.Weak Reference - Object referenced using class will be marked for GC if JVM detects that no strong or soft references are linked to any object.Once the JVM needs memory, GC is required to clear all SoftReference.
#JPROFILER MEMORY LEAK FREE#
Soft Reference - Object referenced using class won’t be collected even if object is free for GC.Object that has a strong reference cannot be collected unless reference points to null. Strong Reference - This is the default object reference.Take a look at the picture below for better understanding.Īlso, there are four types of references in Java that you can use to manage how and when GC to collect objects. Objects that are unreferenced are periodically collected by GC, on the other hand objects that have a valid reference cannot be collected by GC. There are two types, referenced and unreferenced. Whether an object will be removed from working memory depends on the object type. In the long run, accumulating objects and not being able to remove them leads to the OutOfMemoryError Why Object is not Garbage Collected In Java, Memory Leak occurs when an object is no longer being used by an application, but Garbage Collector is not able to remove it from working memory (Heap). In computer science, memory leak means that computer programs incorrectly manage memory allocation by not releasing resources that are not needed. Java Garbage Collector is responsible for allocation and deallocation of objects on Heap. One of the key benefits of Java is that memory management is mainly handled by Java Virtual Machine or more specific Java Garbage Collector (GC). In this story we are going to see what is memory leak, garbage collector, examples of leaks in Java and tools to detect leaks.
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