WeAreDevelopers Logo WeAreDevelopers
Sign in
For You LIVE
World Congress 2026 Europe • Jul 10, 2026 • Session details

Swapping Code, Losing Memory: A JVM Deep Dive

Marco Sussitz

Hot-swapping code is pure magic, until it silently exhausts your off-heap memory. Dive into OpenJDK's C++ core to uncover the hidden metaspace leak crashing your Java applications.

Pause
Mute Enter Fullscreen
#1 about 3 min

Introduction to live debugging and code hot swapping

How live debuggers utilize runtime code manipulation to safely expose running application state inside production environments.

#2 about 3 min

Demonstrating code hot swapping in a running application

How intercepting loaded classes and injecting updated logic via embedded decompilers enables real-time application modifications.

#3 about 3 min

Utilizing the JVM tool interface for dynamic code changes

How debuggers avoid costly virtual machine restarts by utilizing native low-level functions to trigger runtime behavior changes.

#4 about 2 min

Implementing class file load hooks and retransformations

How leveraging class file hooks enables continuous monitoring and dynamic reinjection of updated binary arrays.

#5 about 3 min

Translating low-level structures into basic Java agents

How adopting standard class file transformers bypasses the complexity of constructing binary code replacements manually.

#6 about 3 min

Discovering application crashes caused by excessive code hot swapping

How aggressively applying dynamic breakpoints reveals hidden stability limitations underlying fundamental code reloading mechanisms.

#7 about 2 min

Profiling Java memory to uncover metaspace leaks

How standard flight recording utilities identify persistent meta-space memory leaks hidden beneath apparently healthy heap utilizations.

#8 about 4 min

Isolating metaspace memory leaks with a minimal reproducer

How isolating test conditions and analyzing documentation specifications uncovers architectural boundaries restricting native memory deallocation.

#9 about 3 min

Compiling and configuring the OpenJDK for direct debugging

How compiling internal source elements with active debug symbols enables direct observation of underlying code behaviors.

#10 about 4 min

Debugging internal mixed stack traces to inspect variables

How tracing mixed internal native threads exposes fundamental execution flaws triggering uncontrolled constant pool expansions.

#11 about 2 min

Fixing memory leak bugs by removing unused string constants

How dropping unused reference fields from structural configurations successfully halts excessive memory accumulation across back-to-back updates.

#12 about 2 min

Practical takeaways for investigating obscure runtime memory leaks

Why surfacing obscure defect findings via appropriate ticket channels proves more reliable than forcing complicated local modifications.

Matching moments

6:21 min

Exploring JVM crashes and future debugging trends

Johannes Bechberger · LIVE

8:29 min

Discussion on JIT memory parameters and cross-language benchmarking

Daniel Strmečki · LIVE

1:28 min

Exploring the high-level Java platform debugging architecture

Johannes Bechberger · LIVE

4:09 min

Tooling challenges with debugging, logging, and IDEs

Gonzalo Ortiz Jaureguizar Gonzalo Ortiz Jaureguizar · WWC Europe 2026

4:02 min

Understanding Java virtualization and just-in-time compiler performance challenges

Eric Deandrea Eric Deandrea · WWC 2025

10:03 min

Addressing updates on concurrency extensions and code diagnostics

Mohamed Taman · LIVE

More from World Congress 2026 Europe

Building the Nervous System of AI - Michael Kagan (NVIDIA) thumbnail
29:17
about 1 month ago

Building the Nervous System of AI - Michael Kagan (NVIDIA)

Michael Kagan, Sead Ahmetović

Five Things in Tech that Matter Now - WeAreDevelopers World Congress 2026 Closing Keynote thumbnail
19:41
about 1 month ago

Five Things in Tech that Matter Now - WeAreDevelopers World Congress 2026 Closing Keynote

Christian Heilmann

The Sound of Your Secrets: Teaching Your Model to Spy, So You Can Learn to Defend thumbnail
32:06
about 1 month ago

The Sound of Your Secrets: Teaching Your Model to Spy, So You Can Learn to Defend

David vonThenen

Super scaling for the Super Bowl: How to survive 30 million users hitting your backend in 30 minutes thumbnail
35:13
about 1 month ago

Super scaling for the Super Bowl: How to survive 30 million users hitting your backend in 30 minutes

Irina Branovic

Running Secure Life Science Research at Scale using Hybrid GPU HPC and Kubernetes 🧬 thumbnail
24:23
about 1 month ago

Running Secure Life Science Research at Scale using Hybrid GPU HPC and Kubernetes 🧬

Jeremy Murray

Angstfreude - AI and Corporate Culture - The Thrill and the Threat thumbnail
30:26
about 1 month ago

Angstfreude - AI and Corporate Culture - The Thrill and the Threat

Axel Ebert, Karin Krobath

Upcoming sessions on this topic

Open session

World Congress 2026 North America

Look What Java Can Do Now: Live-Coding a GenAI MCP Server with the JAQ Stack

Suren Konathala

Senior Engineering Leader, Marketing & AdTech, AI GTM & Digital Experience Platforms, Java x AI

Suren Konathala
Open session

World Congress 2026 North America

Offloading IoT State: Solving the Memory Crisis on Legacy Hardware

Pravin Nagare

Senior Software Engineer, Roku

Pravin Nagare
Open session

World Congress 2026 North America

KV Cache Is Not About Speed: It's About Surviving Inference Costs

David vonThenen

AI/ML Leader | Keynote Speaker | OSS Engineer & Developer Advocate | Agentic AI, Deep Learning, Production AI | Python, Go, C++

David vonThenen
Open session

World Congress 2026 North America

public void saveMoney(AI): The Developer's Guide to Unit Economics

Hrushikesh Pokala

Senior Software Engineer Lead at Equifax

Hrushikesh Pokala
Open session

World Congress 2026 North America

When Humans Stop Writing Code: Rethinking Languages, Compilers, and Responsibility

Simon Auer

Organizer of flutter vienna meetup and CEO of marqably

Simon Auer
Open session

World Congress 2026 North America

Merging at Scale: From Broken Builds to Green Mainline

Preetam Dwivedi, Manjari Akella

Preetam Dwivedi
Manjari Akella

Related videos

Debugging Unveiled: Exploring Debugger Internals and Hidden Gems thumbnail
58:23
LIVE • over 2 years ago

Debugging Unveiled: Exploring Debugger Internals and Hidden Gems

Johannes Bechberger

Just-in-time Compilation in JVM thumbnail
37:45
LIVE • almost 5 years ago

Just-in-time Compilation in JVM

Daniel Strmečki

Talk to the Duck - Secrets of the Debugging Masters thumbnail
28:52
WWC 2022 • about 4 years ago

Talk to the Duck - Secrets of the Debugging Masters

Shai Almog

Beam Me Up, Java! Unraveling the Warp-Speed Evolution: A Journey through Java LTS Versions 11 to 21 thumbnail
57:45
LIVE • almost 3 years ago

Beam Me Up, Java! Unraveling the Warp-Speed Evolution: A Journey through Java LTS Versions 11 to 21

Jonathan Vila

Java Sucks (So C# Didn't Have To) thumbnail
29:57
WWC Europe 2026 • about 1 month ago

Java Sucks (So C# Didn't Have To)

Adele Carpenter

Hacking C# from the inside - how to do anything in NET thumbnail
41:54
LIVE • over 5 years ago

Hacking C# from the inside - how to do anything in NET

Adam Furmanek

Related articles

From learning to earning

Jobs that call for the skills explored in this talk.