# GlideinWMS The Glidein-based Workflow Management System

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## GlideinWMS

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### Tutorials

Jump to:

1. Submitting with a VO Frontend
2. Additional Resources
3. Submitting user jobs

Related Links:

- Installation Overview

## Submitting with a VO Frontend

These examples assumes you have GlideinWMS installation running and as a user, you have access to submit jobs. Make sure you have sourced the correct HTCondor installation.
NOTE: It is recommended that you always provide a VOMS proxy in the user job submission. A proxy may also be required for other reasons, such as the job staging data.
The GlideinWMS environment looks almost exactly like a regular, local HTCondor pool. It just does not have any resources attached unless you ask for them; try

    $ condor_status

and you can see that no glideins are connected to your local pool. The GlideinWMS system will submit glideins on your behalf when they are needed. Some information may need to be specified in order for you get glideins that can run your jobs. Depending on your VO Frontend configuration, you may also have to specify additional requirements.

#### Submitting a simple job with no requirements

Here is a generic job that calculates Pi using the monte carlo method. First create a file called pi.py and make it executable:

    #!/bin/env python
    from random import *
    from math import sqrt,pi
    from sys import argv
    inside=0
    n=int(argv[1])
    for i in range(0,n):
        x=random()
        y=random()
        if sqrt(x*x+y*y)<=1:
            inside+=1
    pi_prime=4.0*inside/n
    print pi_prime, pi-pi_prime

You can run it:

    $ ./pi.py 1000000
    3.1428 -0.00120734641021

The first number is the approximation of pi. The second number is how far from the real pi it is. If you repeat this, you will see how the result changes every time.
Now, let's submit this as a HTCondor job. Because we are going to run this multiple times (100), it will actually be a bunch of jobs. These jobs should run everywhere, so we won't need to specify any additional requirements. Create the submit file and call it myjob.sh:

    Universe   = vanilla
    Executable = pi.py
    Arguments  = 10000000
    Requirements = (Arch=!="")
    Log        = job.$(Cluster).log
    Output   = job.$(Cluster).$(Process).out
    Error      = job.$(Cluster).$(Process).err
    should_transfer_files   = YES
    when_to_transfer_output = ON_EXIT
    Queue 100

Next submit the job:

    $ condor_submit myjob.sh

The VO Frontend is monitoring the job queue and user collector. When it sees your jobs and that there are no glideins, it will ask the Factory to provide some. Once the glideins start and contact your user collector, you can see them by running

    $ condor_status

HTCondor will match your jobs to the glideins and the jobs will then run. You can monitor the status of your user jobs by running

    $ condor_q

Once the jobs have finished, you can view the output in the job.$(Cluster).$(Process).out files.

#### Understanding where jobs are running

While your jobs can run everywhere, you may still want to know where they actually ran; possibly because you want to know who to thank for the CPUs you were consuming, or to debug problems you had with your program.
To do this, we add some additional attributes to the submit file:

    Universe   = vanilla
    Executable = pi.py
    Arguments  = 50000000
    Requirements = (Arch=!="")
    Log        = job.$(Cluster).log
    Output   = job.$(Cluster).$(Process).out
    Error      = job.$(Cluster).$(Process).err
    should_transfer_files   = YES
    when_to_transfer_output = ON_EXIT
    +JOB_Site = "$$(GLIDEIN_Site:Unknown)"
    +JOB_Gatekeeper = "$$(GLIDEIN_Gatekeeper:Unknown)"
    Queue 100

These additional attributes in the job are used by the VO Frontend to find sites that match these requirements. HTCondor also uses them to match your jobs to the right glideins.
Now submit the job cluster as before. You can monitor the running jobs with:

    $ condor_q `id -un` -const 'JobStatus==2' -format '%d.' ClusterId -format '%d ' ProcId -format '%s\n' MATCH_EXP_JOB_Site

## Submitting user jobs

From the user point of view, this is just a regular HTCondor pool.
However, since the resources potentially come from all over the world, users need to create more complex Requirements line in their JDL, in order to prevent the jobs from landing on sites that cannot run their jobs.
Users will need to know which attributes the glideins publish and use them accordingly. One useful attribute that all glideins publish is GLIDEIN_Site. If a user wants to restrict its job to a list of sites, he can do it by using:

> +DESIRED_Sites = "Site1,Site4,Site7,Site22"
> Requirements = stringListMember(GLIDEIN_Site,DESIRED_Sites)

Some glideins may also need to properly identify the final user, using GSI authentication. A user should thus add the following line:

> x509userproxy = <path to X509 proxy>

to their HTCondor submission file.

## Additional resources

If you need help debugging issues with running jobs, see our Frontend troubleshooting guide.