Introduction

On this page we'll see how to use Java on the tara cluster. Before proceeding, make sure you've read the How To Run tutorial first. Java is a popular object-oriented programming language used in general-purpose computing.

Java on tara

Currently the system-default Java is the mosy up-to-date

[araim1@tara-fe1 java]$ which javac
/usr/bin/javac
[araim1@tara-fe1 java]$ javac -version
javac 1.6.0_26
[araim1@tara-fe1 java]$

Example batch script

We'll write a simple Java program that says "hello".

class HelloWorld
{  
    public static void main(String args[])
    {
        System.out.println("Hello World!");
    }
}

Download: ../code/java_hello/HelloWorld.java

We can compile and run on the user node to test

[araim1@tara-fe1 java_hello]$ javac HelloWorld.java 
[araim1@tara-fe1 java_hello]$ ls
HelloWorld.class  HelloWorld.java
[araim1@tara-fe1 java_hello]$ java HelloWorld
Hello World!
[araim1@tara-fe1 java_hello]$

We can launch it with a standard SLURM script.

#!/bin/bash
#SBATCH --job-name=hello_java
#SBATCH --output=slurm.out
#SBATCH --error=slurm.err
#SBATCH --partition=develop

java HelloWorld

Download: ../code/java_hello/run.slurm

Now we launch the job

[araim1@tara-fe1 java]$ sbatch run.slurm 
Submitted batch job 99868
[araim1@tara-fe1 java_hello]$ squeue
  JOBID PARTITION     NAME     USER ST       TIME  NODES QOS     NODELIST(REASON)
  99868   develop hello_ja   araim1  R       0:02      1 normal  n1
[araim1@tara-fe1 java_hello]$ cat slurm.out 
Hello World!
[araim1@tara-fe1 java_hello]$ cat slurm.err 
[araim1@tara-fe1 java_hello]$