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Let's explore memory leaks and memory inefficiency patterns in Java backend systems. After reviewing the Java Memory Model and the JVM flags you #musthave in production, we’ll analyze heapdumps of 10 common memory leaks, collected with ❤️ from 150+ companies over a decade of consultancy. You'll hear about ThreadLocal, inner classes, cache/hash keys messup, thread leaks, and many others. In the end, you'll get access to a large repo of memory leaks + heap dumps for later self-study. Oh, and you can get a bounty for any real memory leak you had, which is not yet in that repo 😊.

Devoxx

A live-coding conference talk covering multiple Java memory leak patterns and how to diagnose them. Topics include: configuring JVM flags to capture heap dumps on OOM, using VisualVM/IntelliJ/MAT for heap analysis, shallow vs retained size, high-cardinality Micrometer metrics causing leaks, Hibernate first-level cache accumulation during streaming queries, DIY caches without eviction, broken cache keys due to missing equals/hashCode or mutable keys, inner class hidden references, ThreadLocal leaks in thread pools, BigDecimal parsing of UUID-like strings causing OOM, ArrayList.subList() memory retention, and unbounded CompletableFuture queues. Practical fixes include entity detach, Caffeine cache, try-finally ThreadLocal cleanup, and back-pressure strategies.

How to trace a Java Memory Leak by Victor Rentea