# Flows How-To¶

This is a list of FAQs about the AbiPy flows and the abirun.py script. Feel free to suggest new entries!

Important

The execution of the flows require the proper configuration of manager.yml and, optionally, scheduler.yml. Please consult the documentation available via the abidoc.py script. See FAQ below.

Suggestions:

• Start with the examples available in examples/flows before embarking on large scale calculations.

• Make sure the Abinit executable compiled on the machine can be executed both on the front end and the compute node (ask your sysadmin)

• If you are running on clusters in which the architecture of the compute node is completely different from the one available on the front end, use shell_runner

• Use the debug command

Do not:

• Change manually the input files and the submission scripts

• Submit jobs manually when the scheduler is running

• Use a too small delay for the scheduler

## How to get all the TaskManager options¶

The abidoc.py script provides three commands to get the documentation for the options supported in manager.yml and scheduler.yml.

Use:

abidoc.py manager


to document all the options supported by abipy.flowtk.tasks.TaskManager and:

abidoc.py scheduler


for the scheduler options.

If your environment is properly configured, you should be able to get information about the Abinit version used by the AbiPy with:

abidoc.py abibuild

Abinit Build Information:
Abinit version: 8.7.2
MPI: True, MPI-IO: True, OpenMP: False
Netcdf: True



Important

Netcdf support must be activated in Abinit as AbiPy might use these files to extract data and/or fix runtime errors.

At this point, you can try to run a small flow for testing purpose with:

abicheck.py --with-flow


## How to limit the number of cores used by the scheduler¶

Add the following options to scheduler.yml

# Limit on the number of jobs that can be present in the queue. (DEFAULT: 200)
max_njobs_inqueue: 2

# Maximum number of cores that can be used by the scheduler.
max_ncores_used: 4


## How to reduce the number of files produced by the Flow¶

When running many calculations, Use prtwf -1 to tell Abinit to produce the wavefunction file only if SCF cycle didn’t converged so that AbiPy can reuse the file to restart the calculation.

Note that it’s possible to use:

flow.use_smartio()


to activate this mode for all tasks that are not supposed to produce WFK files for their children.

## How to extend tasks/works with specialized code¶

Remember that pickle does not support classes defined inside scripts (__main__). This means that abirun.py will likely raise an exception when trying to reconstruct the object from the pickle file:

AttributeError: Cannot get attribute 'MyWork' on <module '__main__'


If you need to subclass one of the AbiPy Tasks/Works/Flows, define the subclass in a separated python module and import the module inside your script. We suggest to create a python module in the AbiPy package e.g. abipy/flowtk/my_works.py in order to have an absolute import that allows one to use

from abipy.flowtk.my_works import MyWork


in the script without worrying about relative paths and relative imports.

## Kill a scheduler running in background¶

Use the official API:

abirun.py FLOWDIR cancel


to cancel all jobs of the flow that are in queue and kill the scheduler.

## Compare multiple output files¶

The abicomp.py script

## Try to understand why a task failed¶

There are several reasons why a task could fail. Some of these reasons could be related to hardware failure, disk quota, OS errors or resource manager errors. Others are related to Abinit-specific errors.