The Jalapeño virtual machine

TLDR

Jalapeño is a Java‑based virtual machine designed for Java servers. Its purpose is to meet server performance and scalability demands by building a self‑sufficient VM and an optimizing compiler that targets frequently executed methods. It achieves this with a Java‑written VM that uses a custom object model and memory layout for efficient null checks and array access, implements runtime services in Java, multiplexes threads via virtual processors, supports concurrent allocators and parallel garbage collectors, and provides interoperable compilers for quasi‑preemptive switching and precise reference handling, all backed by a dynamic optimizing compiler.

Abstract

Jalapeño is a virtual machine for Java™ servers written in the Java language. To be able to address the requirements of servers (performance and scalability in particular), Jalapeño was designed "from scratch" to be as self-sufficient as possible. Jalapeño's unique object model and memory layout allows a hardware null-pointer check as well as fast access to array elements, fields, and methods. Run-time services conventionally provided in native code are implemented primarily in Java. Java threads are multiplexed by virtual processors (implemented as operating system threads). A family of concurrent object allocators and parallel type-accurate garbage collectors is supported. Jalapeño's interoperable compilers enable quasi-preemptive thread switching and precise location of object references. Jalapeño's dynamic optimizing compiler is designed to obtain high quality code for methods that are observed to be frequently executed or computationally intensive.