Fyrd is intended to be fully modular, meaning anyone should be able to implement support for any batch system, even other remote submission systems like DistributedPython if they are able to define the following functions and options.

To add a new batch system, you will need to:

1. Edit __init__.py to:
1. Update DEFINED_SYSTEMS to include your batch system
2. Edit get_cluster_environment() to detect your batch system, this function is ordered, meaning that it checks for slurm before torque, as slurm implements torque aliases. You should add a sensible way of detecting your batch system here.
2. Create a file in this directory with the name of your batch system (must match the name in DEFINED_SYSTEMS). This file must contain all constants and functions described below in the Batch Script section.
3. Edit options.py as described below in the Options section.
4. Run the pyenv test suite on your cluster system and make sure all tests pass on all versions of python supported by fyrd on your cluster system.
5. Optionally add a buildkite script on your cluster to allow CI testing. Note, this will technically give anyone with push privileges (i.e. me) the ability to execute code on your server. I promise to do no evil, but I can understand a degree of uncertainty regarding that. However, using buildkite will allow us to make sure that future updates don’t break support for your batch system.
6. Become a fyrd maintainer! I always need help, if you want to contribute more, please do :-)

## Options¶

Fyrd works primarily by converting batch system arguments (e.g. –queue for torque and –partition for slurm) into python keyword arguments. This is done by creating dictionaries in the fyrd/batch_systems/options.py file.

Option parsing is done on job creation by calling the options.options_to_string() function on the user provided keyword arguments. The primary point of this function is to convert all keyword arguments to string forms that can go at the top of your batch file prior to cluster submission. Therefore you must edit the dictionaries in options.py to include your batch system definitions. The most important section to edit is CLUSTER_CORE, this dictionary has sections for each batch system, e.g. for walltime:

('time',
{'help': 'Walltime in HH:MM:SS',
'default': '12:00:00', 'type': str,
'slurm': '--time={}', 'torque': '-l walltime={}'}),


This auto-converts the time argument provided by the user into –time for slurm and -l walltime= for torque.

As all systems are a little different, options.options_to_string() first calls the parse_strange_options() function in the batch system definition script to allow you the option to manually parse all options that cannot be handled so simply. Hopefully this function will do nothing, but return the input, but in some cases it makes sense for this function to handle every argument, an obvious example is when running using something like multiprocessing instead of a true batch system.

### Batch Script¶

The defined batch script must have the name of your system and must define the following constants and functions in exactly the way described below. Your functions can do anything you want, and you can have extra functions in your file (maybe make them private with a leading _ in the name), but the primary functions must take exactly the same arguments as those described below, and provide exactly the same return values.

### Constants¶

• PREFIX: The string that will go before options at the top of a script file, could be blank for simple shell scripts, for slurm is is ‘#SBATCH’

### Functions¶

#### queue_test(warn=True)¶

Input:

• warn: bool, warn on failure, optional

Output:

• functional: bool, True if this system can be used

Description:

Use this function to write code to test that your system can function. If you are using a specific command line tool in your code, consider adding it to the config file to allow users to specify an absolute path or alternate name.

Use a combination of _run.which() (which returns a full path to an executable if the executable is in the user’s PATH and is executable) and _run.is_exe() (which tests if a file is executable) to check your command line tools.

Use the warn parameter with _logme.log() to set a log level, e.g.:

log_level = 'error' if warn else 'debug'
_logme.log('Cannot use me :-(', log_level)


Try not to raise any Exceptions, instead try to just log the problem and return False.

This code is run very frequently to test that the queue is usable, so make your code as simple and efficient as possible.

#### normalize_job_id(job_id)¶

Input:

• job_id: string, return value from job submission

Output:

• job_id: string, a normalized job id
• array_id: string or None, a normalized array job id

Description:

Take a string returned by your job submission script (e.g. qsub) and turn it into a normalized (hopefully string version of an int) job ID or process ID and an array_id, if that is implemented by your system. The array_id can be None if not implemented and should be None if not present (i.e. the job is not an array job).

#### normalize_state(state)¶

Input:

• state: string, a state description from the queue, e.g. ‘running’, or ‘R’

Output:

• state: string, a state normalized into one of: - ‘completed’, - ‘completing’ - ‘held’ - ‘pending’ - ‘running’ - ‘suspended’ - ‘running’ - ‘suspended’

#### gen_scripts(job_object, command, args, precmd, modstr)¶

Input:

• job_object: Job, a fyrd.job.Job object for the current job
• command: string, a string of the command to be run
• args: any additional arguments that are to be submitted, generally not used
• precmd: string, the batch system directives created by options_to_string, you can edit this or overwrite it if necessary
• modstr: string, a string of module imports (e.g. module load samtools) set by the user

Output:

• submission_script: fyrd.submission_scripts.Script object with the script to run
• exec_script: fyrd.submission_scripts.Script object with an additional script called by submission script if necessary, can be None

Description:

This is one of the more complex functions, but essentially you are going to just format the fyrd.script_runners.CMND_RUNNER_TRACK script using the objects in the inputs. This just makes an executable submission script, so you can build this anyway you want, you don’t have to use the CMND_RUNNER_TRACK script. However, if you make your own script, the STDOUT must include timestamps like this:

date +'%y-%m-%d-%H:%M:%S'
echo "Running {name}"
{command}
exitcode=$? echo Done date +'%y-%m-%d-%H:%M:%S' if [[$exitcode != 0 ]]; then
echo Exited with code: $exitcode >&2 fi exit$exitcode


This is because we parse the first two and last 2/3 lines of the file to get the job runtimes and exit codes.

Here is an example function:

def gen_scripts(job_object, command, args, precmd, modstr):
"""Create script object for job, does not create a sep. exec script."""
scrpt = _os.path.join(job_object.scriptpath,
'{}.cluster.qsub'.format(job_object.name))

sub_script = _scrpts.CMND_RUNNER_TRACK.format(
precmd=precmd, usedir=job_object.runpath, name=job_object.name,
command=command
)
return _Script(script=sub_script, file_name=scrpt), None


#### submit(file_name, dependencies=None, job=None, args=None, kwds=None)¶

Input:

• file_name: string, The path to the file to execute [required]
• dependencies: list, A list of dependencies (job objects or job numbers) [optional]
• job: fyrd.job.Job, A job object of the calling job (not always passed) [optional]
• args: list, A list of additional arguments (currently unused) [optional]
• kwargs: dict or str, A dictionary or string of ‘arg:val,arg,arg:val,…’ (currently unused) [optional]

Output:

• job_id: string, A job number

Description:

This function must actually submit the job file, however you want it to. If possible, include dependency tracking, if that isn’t possible, raise a NotImplemented Exception. You can make use of fyrd.run.cmd, which allows you to execute code directly on the terminal and can catch errors and retry submission however many times you choose (5 is a good number). It also returns the exit_code, STDOUT, and STDERR for the execution.

The job object is passed whenever a job is submitted using the normal submission process, and will contain all keyword arguments. If your batch system requires command line arguments, you can parse the keyword arguments with the parse_strange_options function and store them in the submit_args attribute of the Job object. You can then access that attribute in this submission function and pass them to fyrd.run.cmd (or any other method you choose) as command line arguments.

Note, this submit function can also be called on existing scripts without a job object, so your function should not require the job object. The args and kwds arguments exist to allow additional parsing, although they are currently unused; right now args gets the contents of Job.submit_args and kwds gets the contents of the additional_keywords argument to Job.submit(). This argument is currently ignored by all batch scripts.

Please add as much error catching code as possible in the submit function, the torque.py example is a good one.

#### kill(job_ids)¶

Input:

• job_ids: list, A list of job numbers

Output:

• bool: True on success, False on failure

Immediately terminate the running jobs

#### queue_parser(user=None, partition=None)¶

Input:

• user: string, optional username to limit to
• partition: string, optional partition/queue to limit to

(Fine to ignore these arguments if they are not implemented on your system)

Yields (must be an iterator):

• job_id: string
• array_id: string, optional array job number
• name: string, a name for the job
• userid: string, user of the job (can be None)
• partition: string, partition running in (can be None)
• state: string a slurm-style string representation of the state
• nodelist: list, the nodes the job is running on
• numnodes: int, a count of the number of nodes
• threads_per_node: int, a count of the number of cores being used on each node
• exit_code: int, an exit_code (can be None if not exited yet) Must be an int if state == ‘completed’. must be 0 if job completed successfully.

Description:

This is the iterator that is the core of the batch system definition. You must somehow be able to parse all of the currently running jobs and return the above information about every job. If your batch system implements array jobs, this generator must yield one entry per array child, not parent job.

#### parse_strange_options(option_dict)¶

Inputs:

• option_dict: dictionary, a dictionary of keywords from the options.py file prior to interpretation with option_to_string, allowing parsing of all unusual keywords.

Outputs:

• outlist: list, A list of strings that will be added to the top of the submit file
• option_dict: dictionary, A parsed version of option_dict with all options not defined in the appropriate dictionaries in options.py removed.
• other_args: a list of parsed arguments to be passed at submit time, this will be added to the submit_args attribute of the Job or passed as the args argument to submit.

## Summary¶

The modularity of this system is intended to make it easy to support any batch system, however it is possible that some systems won’t fit into the mold defined here. If that is the case, feel free to alter other parts of the code to make it work, but be sure that all tests run successfully on every defined cluster on every supported version of python. Feel free to reach out to me to request testing if you do not have access to any system.