Posts by Jaromir Hamala

I'm a developer at Hazelcast®. I wrote my first line of code when I was 7 years old. Since than I was always interested in "How this system works under the hood?" I like pushing systems towards limits, brushing my skills by exploring HotSpot source code, contributing to open source projects and arguing about development over a pint of beer.

LockSupport.parkNanos() Under the Hood and the Curious Case of Parking, Part II: Windows

by Jaromir Hamala February 18, 2019 0 Comments

In the previous post we have seen how LockSupport.parkNanos() is implemented on Linux, what behavior to expect and how we can tune it. The post was well-received and a few people asked how parkNanos() behaves on Windows. I’ve used Linux…

LockSupport.parkNanos() Under the Hood and the Curious Case of Parking

by Jaromir Hamala January 27, 2019 0 Comments

When a colleague of mine was running some experiments, he noticed LockSupport.parkNanos() would either return almost immediately or in roughly 50 microseconds steps. In other words: Calling LockSupport.parkNanos(10000) would not return after 10 microseconds, but roughly after 50 μs. LockSupport.parkNanos(55000)…

Hazelcast Jet Tutorial: Building Custom JDBC Sinks

by Jaromir Hamala April 18, 2018 Comments Off

Part I: Intro Hazelcast Jet supports writing into a number of 3rd party systems, including HDFS, Apache Kafka and others. But what if you want to write into your own system which is not supported by Jet out-of-the-box? Starting with…

Use Hazelcast Jet to stream data from an IMap to a Kafka topic

by Jaromir Hamala February 7, 2018 Comments Off

Today I would like to show you how to use Hazelcast Jet to stream data from Hazelcast IMDG IMap to Apache Kafka. IMap is a distributed implementation of java.util.Map, it’s super-easy to use and it’s probably the most popular Hazelcast…

Hazelcast IMDG 3.9 Is Out!

by Jaromir Hamala October 25, 2017 Comments Off

We just released Hazelcast IMDG 3.9. It’s a release packed with new features, improvements and optimizations. Let me introduce you to a few of them: User Code Deployment from Clients In Hazelcast IMDG 3.8, we introduced an option for automatic…

The simplest way to integrate Kryo with Hazelcast

by Jaromir Hamala September 13, 2016 Comments Off

Hazelcast offers a bunch of strategies to serialize your domain objects. You can start with simple Java Serialization and change the the strategy when it turns out to be performance bottleneck. It’s also simple to plug-in your own serialization. Kryo…

Hazelcast on AWS – Kernel Bug

by Jaromir Hamala September 7, 2016 Comments Off

The other day we discovered a bug in older Linux kernel versions and I thought you would like to know about it. Summary Use Linux kernel 3.19+ when running Hazelcast on AWS. TCP connections can get stuck with older kernel…