Aamir Shafi, Bryan Carpenter, Mark Baker MPJ Express: An Implementation of MPI in Java Version: 0.35 (Beta Release) Aamir Shafi, Bryan Carpenter, Mark Baker aamir.shafi@seecs.edu.pk, bryan.carpenter@port.ac.uk, mark.baker@computer.org 4/15/2017 http://mpj-express.org

The current release contains: Introduction MPJ Express is a message passing library that be can be used by the application developers to develop and execute parallel Java applications on compute clusters or network of computers. MPJ Express is originally designed for distributed memory machines like clusters but also supports efficient execution of parallel applications on desktops or laptops that contain shared memory or multicore processors MPJ Express is a reference implementation of mpiJava 1.2 API, which is an MPI-like API for Java defined by the Java Grande Forum The current release contains: The core library The runtime infrastructure The test-suite 4/15/2017 http://mpj-express.org

MPJ Express Configurations MPJ Express can be configured in two ways: Multicore Configuration: This configuration is used by developers who want to execute their parallel Java applications on multicore or shared memory machines (laptops and desktops). Cluster Configuration: This configuration is used by developers who want to execute their parallel Java applications on distributed memory platforms including clusters and network of computers. 4/15/2017 http://mpj-express.org

Multicore Configuration The users can use multicore device driver (also known as shared memory device driver) in the multicore configuration Main Memory CPU 0 CPU 1 CPU 2 CPU 3 Proc 0 Proc 1 Proc 2 Proc 3 Fig1: MPJ Express executing in the multicore configuration with four threads on a quad core processor 4/15/2017 http://mpj-express.org

Advantages of Multicore Configuration Incremental Development: Users can first develop parallel applications on desktops/laptops using multicore configuration and then take the same code to distributed memory platforms including clusters Teaching Purposes: This configuration is preferred for teaching purposes since students can execute message passing code on their personal computers Debugging and Profiling: IDEs like Eclipse can be used for easier debugging and profiling 4/15/2017

Cluster Configuration Application developers can opt to use either of the two communication drivers in the cluster configuration Java NIO Device Driver (niodev) It can be used to execute MPJ Express programs on Ethernet-based interconnects. Myrinet Device Driver (mxdev): Many clusters today are equipped with high performance low latency networks like Myrinet. Lets consider a cluster comprising of 8 compute nodes. Every process is started on different node while running code with Cluster Configuration, depending upon the machines file 1 2 3 4 5 6 7 Fig2: MPJ Express executing in the cluster configuration with 8 processes on a cluster with 8 compute nodes 4/15/2017 http://mpj-express.org

MPJ Express Installation (UNIX/Linux/Mac) Pre-requisites Java 1.5 (stable) or higher Apache ant 1.6.2 or higher (Optional) Perl (Optional) Running MPJ Express Programs in the Multicore Configuration Download MPJ Express and unpack it. Set MPJ_HOME and PATH environmental variables: export MPJ_HOME=/path/to/mpj/ export PATH=$PATH:$MPJ_HOME/bin (These above two lines can be added to ~/.bashrc) Write your MPJ Express program (HelloWorld.java) and save it. Compile: javac -cp.:$MPJ_HOME/lib/mpj.jar HelloWorld.java Execute: mpjrun.sh -np 4 HelloWorld.java 4/15/2017 http://mpj-express.org

MPJ Express Installation (UNIX/Linux/Mac) Cont’d Running MPJ Express Programs in the Cluster Configuration Download MPJ Express and unpack it. Set MPJ_HOME and PATH environmental variables: export MPJ_HOME=/path/to/mpj/ export PATH=$PATH:$MPJ_HOME/bin (These above two lines can be added to ~/.bashrc) Write a machines file (name it “machines”) stating hostnames or IP addresses of all the machines involved in the parallel execution Write your MPJ Express program (HelloWorld.java) and save it. Start Daemons: mpjboot machines Compile: javac -cp.:$MPJ_HOME/lib/mpj.jar HelloWorld.java Execute: mpjrun.sh -np 4 HelloWorld.java Stop daemons: mpjhalt machines 4/15/2017 http://mpj-express.org

MPJ Express Installation (Windows) Pre-requisites Java 1.5 (stable) or higher Apache ant 1.6.2 or higher (Optional) Perl (Optional) Running MPJ Express Programs in the Multicore Configuration 1. Download MPJ Express and unpack it. 2. Set MPJ_HOME and PATH environmental variables. Right-click My Computer->Properties->Advanced tab->Environment Variables and export the following system variables (User variables are not enough) Set the value of MPJ_HOME = c:\mpj (assuming mpj is in c:\ Append the c:\mpj\bin directory to the PATH variable Cygwin on Windows: (assuming mpj is 'c:\mpj‘): The recommended way to is to set variables as in Windows. If you want to set variables in cygwin shell export MPJ_HOME="c:\\mpj“ export PATH=$PATH:"$MPJ_HOME\\bin" 4/15/2017 http://mpj-express.org

MPJ Express Installation (Windows) Cont’d Write your MPJ Express program (HelloWorld.java) and save it. Compile: javac -cp.:$MPJ_HOME/lib/mpj.jar HelloWorld.java Execute: mpjrun.bat -np 4 HelloWorld.java For running MPJ Express programs in the cluster configuration, refer to the $MPJ_HOME/README-win.txt and $MPJ_HOME/doc/windowsguide.pdf 4/15/2017 http://mpj-express.org

Writing Programs with MPJ Express A sample Program with MPJ Express is   Save this Program as HelloWorld.java import mpi.*; public class HelloWorld { public static void main(String args[]) throws Exception { MPI.Init(args); int me = MPI.COMM_WORLD.Rank(); int size = MPI.COMM_WORLD.Size(); System.out.println("Hi from <"+me+">"); MPI.Finalize(); } 4/15/2017 http://mpj-express.org

Executing MPJ Express Programs Compiling UNIX/Linux/Mac: javac –cp .:$MPJ_HOME/lib/mpj.jar HelloWorld.java Windows: javac –cp .:%MPJ_HOME%/lib/mpj.jar HelloWorld.java Running with Multicore Configuration UNIX/Linux/Mac: mpjrun.sh –np <no. of processors> HelloWorld.java Windows: mpjrun.bat –np <no. of processors> HelloWorld.java Running with Cluster Configuration Start the daemons UNIX/Linux/Mac: mpjrun.sh –np <no. of processors> -dev niodev HelloWorld Windows: mpjrun.bat –np <no. of processors> -dev niodev HelloWorld 4/15/2017 http://mpj-express.org

Executing Programs with MPJ Express on UNIX/Linux/Mac Multicore Configuration Cluster Configuration Add Snapshots …. First show snapshots for multicore: 1. Logged onto my laptop, which has for example (a quad-core) 2. Execute … 3. and Explain with previous figure how processes are running … 4/15/2017 http://mpj-express.org

Executing Programs with MPJ Express on Windows Multicore Configuration Cluster Configuration Add Snapshots …. First show snapshots for multicore: 1. Logged onto my laptop, which has for example (a quad-core) 2. Execute … 3. and Explain with previous figure how processes are running … 4/15/2017 http://mpj-express.org

Additional Runtime Arguments The mpjrun.[sh/bat] script accepts some additional arguments which can be passed according to the user preferences. Some of them are np switch: If a value is specified, then MPJ Express starts those many processes for the user application. It can be specified like mpjrun.[sh/bat] –np 2 ProgramName. dev switch: This switch can be given at runtime to change to the appropriate device driver. It can be used as mpjrun.[sh/bat] –dev multicore/niodev/mxdev ProgramName. machinesfile switch: While running programs, MPJ Express runtime expects a file with name “machines” in the current directory. User can also specify a machines file with different name using machinesfile switch as mpjrun.[sh/bat] machinesfile myFile ProgramName wdir switch: If your programs reads some file, then it may be a good idea to separate this file from your application classes, or copy it to a tmp directory and specify this tmp directory as working directory using -wdir switch. 4/15/2017 http://mpj-express.org

Manuals and Help Resources Windows Linux README (Quick Start Guide) $MPJ_HOME/README-win.txt $MPJ_HOME/README User Guide $MPJ_HOME/doc/windowsguide.pdf $MPJ_HOME/doc/linuxguide.pdf Visit MPJ Express (http://mpj-express.org) for more details. 4/15/2017 http://mpj-express.org

Contact and Support MPJ Express Users Mailing List (http://www.lists.rdg.ac.uk/mailman/listinfo/mpj-user) Alternatively, the users can contact us directly by email. Aamir Shafi (aamir.shafi@seecs.edu.pk) Bryan Carpenter (bryan.carpenter@port.ac.uk) Mark Baker (mark.baker@computer.org) 4/15/2017

Contributors Aamir Shafi Jawad Manzoor Kamran Hamid Mohsan Jameel Bryan Carpenter Mark Baker Hong Ong Guillermo Taboada Sabela Ramos 4/15/2017 http://mpj-express.org

Acknowledgements The project partners received a generous grant from the British Council under the PMI2 Connect program (http://www.britishcouncil.org/learning-pmi2-connect.htm) Project Title: CollAborative Multicore Programming Using Scientific Java Messaging Project Start Date: September 2008 Duration: 2 Years 4/15/2017 http://mpj-express.org 19