Submitting a Java universe job

What is the Java universe?

Strictly speaking, the Java universe is not necessary because you can use the vanilla universe for Java jobs. However, we discovered that life can get complicated sometimes. For instance, how can Condor tell if a job exited normally but with an error code, or if the Java virtual machine exited abnormally due to a problem with the computer? Condor should act differently in these two cases: if the JVM is bad, another computer can be tried, but if the job failed, that's the fault of the author.

The Java universe addresses this problem, among othersu. There is a really wonderful paper about grid computing and the Java universe, and I can't recommend the paper highly enough. You should read this paper.

Creating a Java program

First you need a Java program. Here's one to start you off. Save it in a file named simple.java.

public class simple
{
    public static void main(String[] args)
    {
        if (args.length != 2) {
            System.out.println("Usage: simple.java <sleep-time> <integer>");
        }
        Integer arg_sleep_time;
        Integer arg_input;

        arg_sleep_time = new Integer(args[0]);
        arg_input      = new Integer(args[1]);

        int sleep_time;
        int input;
        
        sleep_time = arg_sleep_time.intValue();
        input      = arg_input.intValue();

        try {
            System.out.println("Thinking really hard for " + sleep_time + " seconds...");
            Thread.sleep(sleep_time * 1000);
            System.out.println("We calculated: " + input * 2);
        } catch (InterruptedException exception) {
            ;
        }
        return;
    }
}

Then compile and try out the program:

%  javac simple.java

%  ls -lh simple.class
-rw-r-----    1 temp-01  temp-01      1004 Mar 15 17:07 simple.class

%  java simple 4 10
Thinking really hard for 4 seconds...
We calculated: 20

Submitting a Java job

Create a submit file. Note that in the arguments, the first argument is "simple", which is the name of the class you want to invoke. Skipping this argument is a common mistake. Name this file submit.java.

Universe   = java
Executable = simple.class
Arguments  = simple 4 10
Log        = simple.log
Output     = simple.out
Error      = simple.error
Queue

Now submit your job:

% rm simple.log

% condor_submit submit.java
Submitting job(s).
Logging submit event(s).
1 job(s) submitted to cluster 6.

% condor_q


-- Submitter: ws-03.gs.unina.it : <192.167.2.23:34353> : ws-03.gs.unina.it
 ID      OWNER            SUBMITTED     RUN_TIME ST PRI SIZE CMD               
   6.0   temp-01         3/15 17:08   0+00:00:02 R  0   0.0  simple.class simpl

1 jobs; 0 idle, 1 running, 0 held

% condor_q


-- Submitter: ws-03.gs.unina.it : <192.167.2.23:34353> : ws-03.gs.unina.it
 ID      OWNER            SUBMITTED     RUN_TIME ST PRI SIZE CMD               

0 jobs; 0 idle, 0 running, 0 held

% cat simple.log
000 (006.000.000) 03/15 17:08:20 Job submitted from host: <192.167.2.23:34353>
...
001 (006.000.000) 03/15 17:08:24 Job executing on host: <192.167.2.24:34429>
...
005 (006.000.000) 03/15 17:08:28 Job terminated.
        (1) Normal termination (return value 0)
                Usr 0 00:00:00, Sys 0 00:00:00  -  Run Remote Usage
                Usr 0 00:00:00, Sys 0 00:00:00  -  Run Local Usage
                Usr 0 00:00:00, Sys 0 00:00:00  -  Total Remote Usage
                Usr 0 00:00:00, Sys 0 00:00:00  -  Total Local Usage
        0  -  Run Bytes Sent By Job
        0  -  Run Bytes Received By Job
        0  -  Total Bytes Sent By Job
        0  -  Total Bytes Received By Job
...

Congratulations, you've submitted a Java job to Condor!

Java on your Condor pool

Condor keeps track of which computers have a functional Java virtual machine and which version it is. You can find this out by using condor_status:

% condor_status -java

Name          JavaVendor  Ver    State      Activity   LoadAv Mem   ActvtyTime

vm1@server6.g Sun Microsy 1.4.2_ Unclaimed  Idle       0.000   501  0+02:30:09
vm2@server6.g Sun Microsy 1.4.2_ Unclaimed  Idle       0.000   501  0+02:30:05
vm1@ws-01.gs. Sun Microsy 1.4.2_ Unclaimed  Idle       0.000   501  0+01:45:10
vm2@ws-01.gs. Sun Microsy 1.4.2_ Unclaimed  Idle       0.000   501  0+01:45:06
vm1@ws-02.gs. Sun Microsy 1.4.2_ Unclaimed  Idle       0.000   501  0+01:55:10
vm2@ws-02.gs. Sun Microsy 1.4.2_ Unclaimed  Idle       0.000   501  0+01:55:05
...

Next: Coordinating a set of jobs: A simple DAG