1 / 17

Java for High Performance Computing

Java for High Performance Computing. Jordi Garcia Almiñana 14 de Octubre de 1998 de la era post-internet. Index of the Talk. The Java Programming Language Java for Scientific Computation Java limitations for Scientific Computation The Java Runtime System

ace
Download Presentation

Java for High Performance Computing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Java for High Performance Computing Jordi Garcia Almiñana 14 de Octubre de 1998de la era post-internet

  2. Index of the Talk • The Java Programming Language • Java for Scientific Computation • Java limitations for Scientific Computation • The Java Runtime System • The Java Virtual Machine environment • Alternatives to the basic JVM specification • Java for High Performance Computing • Definition of HPC language extensions for Java • Java restructurers, compilers, and optimizers • Parallel systems for High Performance Java

  3. The Java Programming Languaje • Features of Java • Object-Oriented environment • Platform independence • Network support • Security • Runtime environment • Secure remote transactions • Multithreading support • Automatic memory management • Fault tolerance through exception handling Java for High Performance Computing

  4. The Java Programming Languaje • Java for Scientific Computation • OO programming is preferable for design and maintainability • Data type safety • Automatic memory management (garbage collection) • Java arithmetic is fully protable(in other languages, loss of precission in float temporary expressions can give different results) • Truly portable threads and synchronization model • Portable libraries for distributed programming • GUI, programmer force, availability, ... Java for High Performance Computing

  5. The Java Programming Languaje • Java Limitations for Scientific Computation • Java´s floating point restricted specification • Limits exploitation of current and future chips architecture • No support to complex numbers • Internal implementation of arrays • Non-consecutive memory layout scheme • Multidimensional arrays implemented as arrays of arrays(no unrolling, loss of locality, …) • Array boundary checking for every single array access • The Java run-time exception mechanism Java for High Performance Computing

  6. The Java Programming Languaje • Java Limitations for Scientific Computation • No support to high degrees of parallelism • Parallel programming only through threads mechanism • No facility for explicit locality management • Other compiler related issues • Unavailability of the complete program at compile time • The exception mechanism limits code movement • High level abstraction of JVM instruction set hides many machine dependent optimization opportunities Java for High Performance Computing

  7. file.java - Java source code application javac - Java to bytecode translation (performed only once) file.class - Java bytecode class file (JVM instruction set) Network? Java virtualmachine - Java Virtual Machine Specification - format of class files - semantics of instructions The Java Runtime System • Java Virtual Machine: bytecode interpreter Java for High Performance Computing

  8. java virtual machine file.class garbagecollectedheap dynamic class loader standardclasses class verifier operatingsystem executionengine native method linker nativemethods The Java Runtime System • Structure of the Java Virtual Machine • The JVM implementation can be tailored for high performance, low memory use, or portability Java for High Performance Computing

  9. The Java Runtime System • Drawbacks of JVM: Speed! • Java bytecode is interpreted • Bytecode verification rules and exception mechanism • High-level structure about original program is lost • Local view during invocation of classes • Stack-based operands (no registers) • Alternatives: • Just-in-time code generation • Java static compilation to native code • Java OS and Java Processors Java for High Performance Computing

  10. The Java Runtime System • Just-in-time Code Generation • Java bytecode to native object code on-the-fly • Just before the method is run for the first time • Based on the idea of inlining the machine code • Certain optimizations can be performed • Elimination of redundant instructions • Use hardware registers for local variables • Optimization of method stack usage • However compilation speed requirements constrain the quality of the optimizations • Improvements over interpretation by a factor of 10! Java for High Performance Computing

  11. The Java Runtime System • Java Static Compilation to Native Code • Traditional resource-intensive optimization techniques can improve the performance of the generated code • instruction schedulling • common subexpression elimination • inter-module analysis • constant propagation • global register allocation • Run time checking can be optimized or removed • …but portability and security can be lost! Java for High Performance Computing

  12. The Java Runtime System • Java OS • Java applications run directly on hardware platforms without requiring a host OS • Java Processors • Hardware implementation of a Java interpreter • Chips created specifically to run Java bytecode • Sun implementations: picoJava, microJava Java for High Performance Computing

  13. file.java javac file.class Java virtualmachine Java for HPC • Different levels of research - Language extension - Mathematical libraries - Restructuring compiler - Bytecode optimization - JIT optimization techniques - Runtime parallel kernel library - Parallel Java Virtual Machine - Hardware Java implementations Java for High Performance Computing

  14. Java for HPC • HPC Language Extensions for Java • Language extension • multidimensional arrays • data parallel distributed loops • communication primitives • Java numerical (matrix-oriented) libraries • Floating-point precission and complex numbers • Other Java Dialects • Titanium: language and system for parallelism • Spar: semi-automatic parallel compilation Java for High Performance Computing

  15. Java for HPC • Java Restructurers • Source-to-source tools that extract parallelism(implicitly from loops or explicitly from annotations) • Java Compilers • Java to parallel bytecode translation • Definition of IR for parallel optimization • Bytecode Optimizers • Techniques for automatic detection of parallelism • Machine-dependent optimizations • Just-in-time optimizations Java for High Performance Computing

  16. Java for HPC • Parallel Systems for HPC in Java • Parallel implementation of a JVM • Programming based on SPMD Java • Based on PVM or MPI implementations • Environment definition for network parallel programs • Heterogeneous environment(run-time systems or parallel libraries) • Parallel sparse computation in Java • Runtime environment with continuous compilation Java for High Performance Computing

  17. The Survey • Available (under construction) at URL: file:/usr/users.coderch/ac/jordig/pub/Java4HPC/main.html Java for High Performance Computing

More Related