The Open Runtime Platform: a flexible high-performance managed runtime environment

The Open Runtime Platform (ORP) is a high-performance managed runtime environment (MRTE) that features exact generational garbage collection, fast thread synchronization, and multiple coexisting just-in-time compilers (JITs). ORP was designed for flexibility in order to support experiments in dynamic compilation, garbage collection, synchronization, and other technologies. It can be built to run either Java or Common Language Infrastructure (CLI) applications, to run under the Windows or Linux operating systems, and to run on the IA-32 or Itanium processor family (IPF) architectures. Achieving high performance in an MRTE presents many challenges, particularly when flexibility is a major goal. First, to enable the use of different garbage collectors and JITs, each component must be isolated from the rest of the environment through a well-defined software interface. Without careful attention, this isolation could easily harm performance. Second, MRTEs have correctness and safety requirements that traditional languages, such as C++, lack. These requirements, including null pointer checks, array bounds checks, and type checks, impose additional runtime overhead. Finally, the dynamic nature of MRTEs makes some traditional compiler optimizations, such as devirtualization of method calls, more difficult to implement or more limited in applicability. To get full performance, JITs and the core virtual machine (VM) ∗ Other brands and names are the property of their respective owners.  Itanium is a registered trademark of Intel Corporation or its subsidiaries in the United States and other countries. must cooperate to reduce or eliminate (where possible) these MRTE-specific overheads. In this paper, we describe the structure of ORP in detail, paying particular attention to how it supports flexibility while preserving high performance. We describe the interfaces between the garbage collector, the JIT, and the core VM; how these interfaces enable multiple garbage collectors and JITs without sacrificing performance; and how they allow the JIT and the core VM to reduce or eliminate MRTE-specific performance issues.