JetBrains Xodus is a Java transactional schema-less embedded database used by JetBrains YouTrack and JetBrains Hub.
ReactiveSocket Protocol for Client/Server for Java
High Performance data structures and utility methods for Java
Efficient reliable UDP unicast, UDP multicast, and IPC message transport
Chronicle Bytes has a similar purpose to Java NIO's ByteBuffer with many extensions
Automated Git clone of various OpenJDK branches (now including JDK 6, 7, 8, and 9) - check out the NEW jdk9/consol-proto experimental consolidated branch!
Enterprise Integration Done Right — Alpakka
Algorithms and Data Structures implemented in Java
The Streaming-first HTTP server/module of Akka
DynamoDBJournal for Akka Persistence
A lightning fast, transactional, file-based FIFO for Android and Java.
Simple Binary Encoding (SBE)
Lightweight ATS framework for Interactive Brokers using Scala and Akka.
A Scala encapsulation of the Interactive Broker's Java API
A high performance, low latency, reactive processing framework
Micro second messaging that stores everything to disk
Global-scale event sourcing and event collaboration with causal consistency
Conformance tests for SBE implementations
MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap-memory. It is a fast and easy to use embedded Java database engine.
Low level access to native memory, JVM and OS.
Using AWS SDK on the Scala REPL
Open source tools to simplify Akka event sourcing, journaling/persistence, serialization, clustering and sharding.
Replicate your Key Value Store across your network, with consistency, persistance and performance.