Skip to content

OSG Exercise 1.2: Running Jobs in OSPool

The goal of this exercise is to map the physical locations of some Execution Points in the OSPool. We will provide the executable and associated data, so your job will be to write a submit file that queues multiple jobs. Once complete, you will manually collate the results.

Where in the world are my jobs?

To find the physical location of the computers your jobs our running on, you will use a method called geolocation. Geolocation uses a registry to match a computer’s network address to an approximate latitude and longitude.

Geolocating several Execution Points

Now, let’s try to remember some basic HTCondor ideas from the HTC exercises:

  1. Log in to ap40.uw.osg-htc.org if you have not yet.
  2. Create and change into a new folder for this exercise, for example osg-ex12

  3. Download the geolocation code:

    $ wget http://proxy.chtc.wisc.edu/SQUID/osgschool21/location-wrapper.sh \
       http://proxy.chtc.wisc.edu/SQUID/osgschool21/wn-geoip.tar.gz

    You will be using location-wrapper.sh as your executable and wn-geoip.tar.gz as an input file.

  4. Create a submit file that queues fifty jobs that run location-wrapper.sh, transfers wn-geoip.tar.gz as an input file, and uses the $(Process) macro to write different output and error files. Also, add the following requirement to the submit file (it’s not important to know what it does):

    requirements = (HAS_CVMFS_oasis_opensciencegrid_org == TRUE) && (IsOsgVoContainer =!= True)

    Try to do this step without looking at materials from the earlier exercises. But if you are stuck, see HTC Exercise 2.2.

  5. Submit your jobs and wait for the results

Collating your results

Now that you have your results, it’s time to summarize them. Rather than inspecting each output file individually, you can use the cat command to print the results from all of your output files at once. If all of your output files have the format location-#.out (e.g., location-10.out), your command will look something like this:

$ cat location-*.out

The * is a wildcard so the above cat command runs on all files that start with location- and end in .out. Additionally, you can use cat in combination with the sort and uniq commands using "pipes" (|) to print only the unique results:

$ cat location-*.out | sort | uniq

Mapping your results

To visualize the locations of the Execution Points that your jobs ran on, you will be using http://www.mapcustomizer.com/. Copy and paste the collated results into the text box that pops up when clicking on the 'Bulk Entry' button on the right-hand side. Where did your jobs run?

Next exercise

Once completed, move onto the next exercise: Hardware Differences in the OSG

Extra Challenge: Cleaning up your submit directory

If you run ls in the directory from which you submitted your job, you may see that you now have thousands of files! Proper data management starts to become a requirement as you start to develop true HTC workflows; it may be helpful to separate your submit files, code, and input data from your output data.

  1. Try editing your submit file so that all your output and error files are saved to separate directories within your submit directory.

    Tip

    Experiment with fewer job submissions until you’re confident you have it right, then go back to submitting 500 jobs. Remember: Test small and scale up!

  2. Submit your file and track the status of your jobs.

Did your jobs complete successfully with output and error files saved in separate directories? If not, can you find any useful information in the job logs or hold messages? If you get stuck, review the slides from Tuesday.