Gerrit Grunwald
where else to find them
website:http://www.harmonic-code.org
github:HanSolo
bluesky:hansolo.eu
mastodon:@hansolo_@mastodon.social
x:hansolo_
linkedin:gerritgrunwald
speakerdeck:hansolo_
what they talk about
all 13 in the filters
where they keep going back
- JCON EUROPE4 editions2023–2026
- Jfokus3 editions2018–2023
- Devnexus2 editions2022–2025
all 19 in the filters
on a stage with
- Jim Weaveronce
- Simon Ritteronce
- Yolande Poirieronce
who talks about the same things
- Simon Ritter72 talks
- Mohammed Aboullaite32 talks
- Ionut Balosin13 talks
- Andrzej Grzesik24 talks
- Piotr Przybył41 talks
- Maurice Naftalin30 talks
| title | conference | date |
|---|---|---|
| Scotty, I need Warp Speed - Ways to improve JVM startup | JNation 2026 | 2026-05-26 |
JVM startup bottlenecks center on class loading (the JVM loads ~1,200 classes; frameworks can add tens of thousands), interpretation and tiered JIT warm‑up… | ||
| JVM internals — bytecode, JIT, GC, speculative optimization | JCON EUROPE 2026 | 2026-04-20 |
The JVM loads, verifies, and initializes classes, runs bytecode through a template interpreter (precompiled machine-code stubs), then tiers to a fast C1 JIT… | ||
| A Journey - On Tour with Java Code on It’s Way Through the JVM | JCON EUROPE 2026 | 2026-04-20 |
Java source compiles with JavaC into bytecode class files, then the JVM class loader chain (bootstrap → platform → system → optional custom) brings classes… | ||
| Trash Talk - Exploring the memory management in the JVM | Øredev 2025 | 2025-11-05 |
Covers concrete JVM behavior: mark‑and‑sweep, copy and compact strategies, and generational collection with Eden/survivor/old regions; lists collectors with… | ||
| Trash Talk - Exploring the Memory Management in the JVM | DevDays || DevOps Pro || CyberWiseCon Europe 2025 | 2025-05-20 |
Covers concrete JVM collectors, tradeoffs and numbers: serial GC uses one thread and often runs on tiny nodes or <1.8 GB defaults; parallel GC gives throughput… | ||
| We Hate Code - The !joy of Maintaining Dead Code | JCON EUROPE 2025 | 2025-05-12 |
Claims that large Java codebases contain massive unused logic surface up: one customer measures 70% unused and personal testing finds only 37% used; industry… | ||
| Trash Talk - Exploring the JVM memory system | Voxxed Days Bucharest 2025 | 2025-03-27 |
JVM garbage collection directly changes latency, CPU and memory behavior: default is G1 default since JDK9 but JVM picks the serial collector for single‑CPU or… | ||
| We Hate Code: The !Joy of Maintaining Dead Code | Devnexus 2025 | 2025-03-04 |
Conference claims a customer had 50% of deployed code unused and estimates legacy/dead-code costs at billions; it demonstrates tools and workflows: static IDE… | ||
| Trash Talk: Exploring the JVM memory management | Voxxed Days CERN 2025 | 2025-01-15 |
Clear, practical tour of JVM collectors that names tradeoffs and real thresholds: OpenJDK chooses the serial collector for heaps under 1.8 GB which can… | ||
| Trash Talk - Exploring the JVM memory management | Devoxx Belgium 2024 | 2024-10-07 |
Covers how the JVM traces, reclaims and compacts memory, with concrete tradeoffs: stop-the-world pauses for simple collectors, most objects die young… | ||
| Trash Talk - Exploring the memory management in the JVM | JNation 2024 | 2024-06-04 |
Covers how the JVM lays out stack, heap and metaspace and walks concrete algorithms: mark‑sweep fragmentation, mark‑compact compaction costs, copy and… | ||
| What the CRaC - Superfast JVM Startup | DevDays Europe 2024 | 2024-05-20 |
Overview of a concrete fix: an OpenJDK project CRaC uses Linux CRIU to take a warmed JVM snapshot and restore it later, cutting Spring PetClinic startup from… | ||
| Trash Talk - Exploring the JVM memory management | GeeCON 2024 | 2024-05-15 |
Practical overview of JVM collectors with concrete tradeoffs: shows Serial/Parallel (stop-the-world vs threaded GC), explains generational GC with… | ||
| Trash Talk - Exploring the Memory Management in the JVM | JCON EUROPE 2024 | 2024-05-13 |
Fast, clear rundown of how JVM collectors actually work: Mark‑sweep fragments, Mark‑compact trades free space for compaction time, copy collectors need 2x… | ||
| Wargames - Java vulnerabilities and why you should care | Voxxed Days Ticino 2024 | 2024-01-19 |
Explains CVE/NVD/CVSS scores and shows concrete risks: JDK 17 accumulates ~61 public CVEs if left unpatched, and quarterly CPU vs PSU timing matters because a… | ||
| Wargames - Java vulnerabilities and why you should care | J-Fall 2023 | 2023-11-09 |
Explains concrete Java security plumbing: how NVD/CVE/CVSS work and why CVE-2021-44228 (Log4Shell) scores 10.0 CVSS3.1, why a JDK left at 17 GA accumulates ~55… | ||
| Welcome to the Jungle - A safari through the JVM landscape | Devoxx Ukraine 2023: AI – Friend or Foe? | 2023-09-22 |
Overview of the JVM ecosystem that names the concrete tradeoffs: OpenJDK is source only while many distributions (≈20+ builds) provide binaries with different… | ||
| Welcome to The Jungle - A Safari Through The JVM Landscape | JCON Europe 2023 | 2023-06-20 |
Comparison of 20+ OpenJDK-based distributions with concrete differences: 6‑month STS cadence vs LTS (8,11,17,21), patch types (CPU only from Azul, BellSoft and… | ||
| Wargames - Java Vulnerabilities and Why You Should Care | JCON Europe 2023 | 2023-06-20 |
Explains that Log4Shell (CVE-2021-44228) had CVSS jump from 9.3 to 10 and that many systems still pull vulnerable Log4j (about 34% months later), cites… | ||
| Welcome to the Jungle - A safari through the JVM landscape | GeeCON 2023 | 2023-04-19 |
Survey of practical differences among JVM builds not generalities you already know It lists 20+ OpenJDK distributions, shows which ones pass TCK and AquaVit… | ||
| Welcome to the Jungle - A safari through the JVM landscape | Jfokus 2023 | 2023-02-06 |
A tour of JVM builds compares concrete differences: which distributions provide CPU (security) updates (Azul, BellSoft, Oracle) versus PSUs, which are… | ||
| What the CRaC Superfast JVM startup | Voxxed Days Cluj-Napoca 2022 | 2022-10-05 |
CRaC (Coordinated Restore at Checkpoint) uses a patched OpenJDK (demo build jdk 17.0.2) plus CRIU to snapshot a warmed JVM to disk and restore it later… | ||
| Disco API - OpenJDK distributions as a service | Jfokus 2022 | 2022-05-02 |
Disco API at foojay.io provides a vendor-neutral discovery service for OpenJDK builds across many distributions and versions, exposing simple endpoints… | ||
| May JavaFX be with you always | Devnexus 2022 | 2022-04-12 |
Recreates a macOS diabetes-monitoring app as GlucoStatusFX and gets it running on desktop, browser and mobile; CSS replicates the mac header (height 52.5, four… | ||
| Java on CRaC Superfast JVM Application Startup | Devnexus 2022 | 2022-04-12 |
CRaC implements checkpoint/restore for JVMs inside OpenJDK using Linux’s CRIU to snapshot a warmed JVM, adding a Resource API with… | ||
| Disco API: OpenJDK Distributions As A Service | FOSDEM 2021 | 2021-02-06 |
At Azul, we have spent some time to create a little API that should help you to discover builds of OpenJDK from different distributions in a general way.
In… | ||
| Java on the Desktop | Voxxed Days Banff 2019 | 2019-09-20 |
JavaFX remains a practical desktop choice: OpenJFX on GitHub is actively developed, Gluon compiles JavaFX to native mobile apps, and JPro renders to SVG to run… | ||
| One control to rule them all | Jfokus 2018 | 2018-02-05 |
MultiDevice controls adapt UI between desktop and mobile and let a phone act as a direct input device for desktop software; a working JavaFX demo shows a… | ||
| Healthcare for the Elderly Using the IoT | GOTO Berlin 2015 | 2015-12-03 |
A prototype system combines Bluetooth LE iBeacons for room changes, accelerometers and Google Fit for step counts, GPS for outdoor geofences, a plug‑in power… | ||
| Healthcare for the Elderly using the IoT | J-Fall 2015 | 2015-11-05 |
A prototype links a Java-based gateway with a smartphone, smartwatch and iBeacons for room-level location to monitor countryside elders, detect falls… | ||
| The New Internet of Things Community | Devoxx 2013 | 2013-11-11 |
A community site on java.net aggregates IoT blogs, project docs and recordings and runs a Raspberry Pi and Arduino hackafest where teams build projects over a… | ||
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