The goal of this exercise is to submit jobs to HTCondor and have them run on the local pool (CHTC). This is a huge step in learning to use an HTC system!
Running a Simple Job[edit | edit source]
Nearly all of the time, when you want to run an HTCondor job, you first write an HTCondor submit file for it. In this section, you will run the same
hostname command as in the last exercise, but where this command will run within a job on one of the 'execute' servers in CHTC's local HTCondor pool.
Here is a simple submit file for the
executable = /bin/hostname output = simple.out error = simple.err log = simple.log request_cpus = 1 request_memory = 1MB request_disk = 1MB queue
Write those lines of text in a file named
NOTE! There is nothing magic about the name of an HTCondor submit file. It can be any filename you want. It's a good practice to always include the
.sub extension, but it is not required. Ultimately, a submit file is a text file
The lines of the submit file have the following meanings:
||The name of the program to run (relative to the directory from which you submit).|
||The filename where HTCondor will write the standard output from your job.|
||The filename where HTCondor will write the standard error from your job. This particular job is not likely to have any, but it is best to include this line for every job.|
||The filename where HTCondor will write information about your job run. Technically not required, it is a really good idea to have a log file for every job.|
|| Tells HTCondor how many |
||Tells HTCondor to run your job with the settings above.|
Note that we are not using the
arguments lines or
transfer_input_files because the
hostname program is all that needs to be transferred from the submit server, and we want to run it without any additional options.
Double-check your submit file, so that it matches the text above. Then, tell HTCondor to run your job:
username@learn $ condor_submit simple.sub Submitting job(s). 1 job(s) submitted to cluster NNNN.
The actual cluster number will be shown instead of
NNNN. If, instead of the text above, there are error messages, read them carefully and then try to correct your submit file or ask for help.
condor_submit returns back to the shell prompt right away. It does not wait for your job to run. Instead, as soon as it has finished submitting your job into the queue, the submit command finishes.
View your job in the queue[edit | edit source]
condor_q -nobatch to watch for your job in the queue!
You may not even catch the job in the
R running state, because the
hostname command runs very quickly. When the job itself is finished, it will 'leave' the queue and no longer be listed in the
After the job finishes, check for the
hostname output in
simple.out, which is where job information printed to the terminal screen will be printed for the job.
username@learn $ cat simple.out e171.chtc.wisc.edu
simple.err file should be empty, unless there were issues running the
hostname executable after it was transferred to the slot. The
simple.log is more complex and will be the focus of a later exercise.
Running a Job With Arguments[edit | edit source]
Very often, when you run a command on the command line, it includes arguments (i.e. options) after the program name, as in the below examples:
username@learn $ cat simple.out username@learn $ sleep 60 username@learn $ dc -e '6 7 * p'
In an HTCondor submit file, the program (or 'executable') name goes in the
executable statement and all remaining arguments go into an
arguments statement. For example, if the full command is:
username@learn $ sleep 60
Then in the submit file, we would put the location of the "sleep" program (you can find it with
which sleep) as the job
60 as the job
executable = /bin/sleep arguments = 60
For the command-line command:
username@learn $ dc -e '6 7 * p'
We would put the following into the submit file, putting the
arguments statement in quotes, since it contains single quotes:
executable = /usr/bin/dc arguments = "-e '6 7 * p'"
Letâ€™s try a job submission with arguments. We will use the
sleep command shown above, which simply does nothing for the specified number of seconds, then exits normally. It is convenient for simulating a job that takes a while to run.
Create a new submit file (you name it this time) and save the following text in it.
executable = /bin/sleep arguments = 60 output = sleep.out error = sleep.err log = sleep.log request_cpus = 1 request_memory = 1MB request_disk = 1MB queue
Except for changing a few filenames, this submit file is nearly identical to the last one. But, see the extra
Submit this new job. Again, watch for it to run using
condor_q -nobatch; check once every 15 seconds or so. Once the job starts running, it will take about 1 minute to run (because of the
sleep command, right?), so you should be able to see it running for a bit. When the job finishes, it will disappear from the queue, but there will be no output in the output or error files, because
sleep does not produce any output.
Running a Script Job From the Submit Directory[edit | edit source]
So far, we have been running programs (executables) that come with the standard Linux system. More frequently, you will want to run a program that exists within your directory or perhaps a simple shell script of commands that you'd like to run within a job. In this example, you will write a shell script and a submit file that runs the shell script within a job:
Put the following contents into a file named
#!/bin/sh echo 'Date: ' `date` echo 'Host: ' `hostname` echo 'System: ' `uname -spo` echo "Program: $0" echo "Args: $*" echo 'ls: ' `ls` # END
Add executable permissions to the file (so that it can be run as a program):
username@learn $ chmod +x test-script.sh
Test your script from the command line:
username@learn $ ./test-script.sh hello 42 Date: Mon Jul 17 10:02:20 CDT 2017 Host: learn.chtc.wisc.edu System: Linux x86_64 GNU/Linux Program: ./test-script.sh Args: hello 42 ls: hostname.sub montage simple.err simple.log simple.out test-script.sh
This step is really important! If you cannot run your executable from the command-line, HTCondor probably cannot run it on another machine, either. And debugging simple problems like this one is surprisingly difficult. So, if possible, test your
argumentsas a command at the command-line first.
Write the submit file (this should be getting easier by now):
executable = test-script.sh arguments = foo bar baz output = script.out error = script.err log = script.log request_cpus = 1 request_memory = 1 request_disk = 1 queue
In this example, the
executablethat was named in the submit file did not start with a
/, so the location of the file is relative to the submit directory itself. In other words, in this format the executable must be in the same directory as the submit file.
**NOTE!** this example shows, blank lines and spaces around the = sign do not matter to HTCondor. Use whitespace to make things clear to you. What format do you prefer to read?
Submit the job, wait for it to finish, and check the output (and error, which should be empty).
What do you notice about the lines returned for "Program" and "ls"? Remember that only files pertaining to this job will be in the job working directory on the execute server. You're also seeing the effects of HTCondor's need to standardize some filenames when running your job, though they are named as you expect in the submission directory (per the submit file contents).
Extra Challenge[edit | edit source]
NOTE! There are Extra Challenges throughout the school curriculum. You may be better off coming back to these after you've completed all other exercises for your current working session.
Below is a simple Python script that does something similar to the shell script above. Run this Python script using HTCondor.
#!/usr/bin/env python import getpass import os import platform import socket import sys import time arguments = None if len(sys.argv) > 1: arguments = '"' + ' '.join(sys.argv[1:]) + '"' print >> sys.stderr, __doc__ print 'Time :', time.strftime('%Y-%m-%d (%a) %H:%M:%S %Z') print 'Host :', getpass.getuser(), '@', socket.gethostname() uname = platform.uname() print "System :", uname, uname, uname print "Version :", platform.python_version() print "Program :", sys.executable print 'Script :', os.path.abspath(__file__) print 'Args :', arguments
NOTE! For the Python script, above, you'll want to increase the memory request to at least 64MB. We will talk about tuning resource requests, later.