Java memory leak – application heap usage growing, leading to OutOfMemoryError

My Java service gradually consumes more heap memory over time, eventually throwing java.lang.OutOfMemoryError: Java heap space. How do I detect and resolve such a memory leak?

Even with automatic garbage collection, memory leaks occur if references remain live—especially in static fields, caches, or forgotten listener registrations (turn0reddit22 Reddit). How to diagnose: • Monitor heap over time using tools like VisualVM, Eclipse MAT, or jcmd with JFR to pinpoint allocation paths to GC roots (turn0reddit17 Reddit). Common causes & fixes: • Static collections or Singleton caches holding ever-increasing data → clear or limit size. • Unclosed resources (I/O streams, JDBC connections) → always use try-with-resources. • Persistent event listeners or timers → deregister when not needed. • Memory held in ThreadLocal across thread pools → call threadLocal.remove() when done. By profiling memory and cleaning unused references, leaks can be prevented and performance maintained.

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