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One day, I ran into SwissTable—the kind of design that makes you squint, grin, and immediately regret every naive linear-probing table you’ve ever shipped. This post is the story of how I tried to bring that same “why is this so fast?” feeling into Java. It’s part deep dive, part engineering diary, and part cautionary tale about performance work. 1) The SwissTable project, explained the way it feels when you first understand it SwissTable is an open-addressing hash table design that came out of Google’s work and was famously presented as a new C++ hash table approach (and later shipped in Abseil). ...

Swiss Tables:A Modern, High-Performance Hash Table Swiss Table is a high-performance hash table design introduced by Google engineers in 2017. It has since inspired many standard-library implementations across languages, including: Go 1.24 ships its map with this design (up to 60% faster) Rust’s standard HashMap has also moved from Robin Hood hashing to a Swiss Table-inspired layout. Datadog reported as much as 70% memory savings after migrating to Swiss Table Open Addressing, Briefly An open addressing hash table is one of the implementation methods for hash tables. Unlike separate chaining — which uses external data structures such as linked lists or trees — open addressing implements the entire hash table as a single contiguous array. ...

Limitations of Traditional Scalar State Machine Parsers The JSON parsing algorithms we commonly use are based on scalar state machine parsers. Scalar parsers read the input string byte by byte, parsing it through state transitions within the state machine. For example: When encountering a quotation mark ("), it indicates the start of a string. When encountering a colon (:), it indicates that a value is expected next. Below is a simplified pseudo-code representation of how a scalar parser works ...

This post explains how coroutines work, referencing the design proposal Kotlin Proposals - Coroutines. Coroutine The proposal describes a coroutine in one sentence as an instance of suspendable computation. The essential trait of a coroutine is its ability to suspend. So what exactly does “suspendable” mean? Suspension According to the proposal, suspendable means a coroutine can pause execution on the current thread, yield the thread so another coroutine can run, and later resume—possibly on a different thread. ...