( Note: If you have a good handle on the intricacies of memory leaks, you can skip ahead.) Memory Leaks: A Primerįor starters, think of memory leakage as a disease and Java’s OutOfMemoryError (OOM, for brevity) as a symptom. In this memory management tutorial, I’ll focus on Java heaps leaks and outline an approach to detect such leaks based on Java VisualVM reports and utilizing a visual interface for analyzing Java technology-based applications while they’re running.īut before you can prevent and find memory leaks, you should understand how and why they occur. Native memory leaks: associated with any continuously growing memory utilization that is outside the Java heap, such as allocations made by JNI code, drivers or even JVM allocations. This is usually caused by latent object references. Java heap leaks: the classic memory leak, in which Java objects are continuously created without being released. Resource constraints: occurs when there’s either to little memory available or your memory is too fragmented to allocate a large object-this can be native or, more commonly, Java heap-related. Performance: usually associated with excessive object creation and deletion, long delays in garbage collection, excessive operating system page swapping, and more. There actually four categories of memory issues with similar and overlapping symptoms, but varied causes and solutions: In other words, leaks are either too hard to identify, or identified in terms that are too specific to be useful. To make things worse, detecting these leaks can be difficult: static analysis often struggles to precisely identify these redundant references, and existing leak detection tools track and report fine-grained information about individual objects, producing results that are hard to interpret and lack precision. For one, they put unnecessary pressure on your machine as your programs consume more and more resources. Let me explain.Ī memory leak occurs when object references that are no longer needed are unnecessarily maintained. This is a common misperception: while the garbage collector does its best, it’s entirely possible for even the best programmer to fall prey to crippling memory leaks. Inexperienced programmers often think that Java’s automatic garbage collection completely frees them from worrying about memory management.
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