Detour to continue a multi-task firework

[Guido Petretto]

Hello,

I am facing the following problem: I am in a configuration with a multi-task firework. From a task in this firework I would like to create a detour of the current firework so that it will only execute the remaining tasks in the new firework. The structure of the firework is not strictly fixed and it would be basically impossible to have a different function to handle each different case.

As a potential solution, the full list of tasks in the firework can be taken from the `_tasks` attribute in the `fw_spec`, so the problem is to figure out the task being executed in this list. After giving some though I concluded that a clean way could be to have access directly to the index of the task: for example having a new reserved keyword in `fw_spec` (e.g. _task_index) that will be set by the rocket runner with the index of the current task in the firework.

Since I am not sure if this would be an acceptable update, I wanted to check if somebody else already had a similar problem and came up with smarter solution. Or otherwise if I can proceed to implement this in fireworks.

Alternative solutions I have thought about include:

- identifying the task being executed based on the class of the task itself: may not work as more than one task with the same class could be present. One could further inspect the task and try to distinguish them based on some attribute, but this could become tricky

- adding an index to each task myself: this would work but it seems much more difficult to maintain compared to having this index directly from fireworks.

Thanks.

Guido

[Anubhav Jain]

Hi Guido,

If I understand correctly, you are looking to find out which tasks were executed already in a Firework that is running.

There is some code in rocket.py that creates a checkpoint as the tasks in a Firework run:

                checkpoint = {'_task_n': t_counter,

                              '_all_stored_data': all_stored_data,

                              '_all_update_spec': all_update_spec,

                              '_all_mod_spec': all_mod_spec}

                Rocket.update_checkpoint(lp, launch_dir, launch_id, checkpoint)

This updates the "state_history" attribute of a launch with information about the task number.

Currently, this code is used for task-level reruns. For example, if a Firework FIZZLES at task #4 within the Firework, this checkpoint information can be used to rerun the Firework only at task #4 if desired.

It's possible this same feature could be used for what you are trying to accomplish?

[Anubhav Jain]

(note that you might need to use the "_add_launchpad_and_fw_id" option in the spec to be able to look up the Launch object and corresponding "task_n"

[Guido Petretto]

Hi Anubhav,

thanks for the tip. I was aware of the presence of the checkpoint, but I did not think of using it in this case. I can definitely use it to solve the problem in my workflow.

As a side note, it seems a bit of a waste passing through the database to get access to a value that is available locally. Thanks to your suggestion I already have a solution, but if you think that it could be beneficial I am available to add this value to the spec or as an attribute of the task.

Thanks,

Guido

[Anubhav Jain]

Hi Guido

For the way FireWorks is currently set up, the task that is currently executing is a property of the launch and not of the FireWork itself. The goal of the FireWork is supposed to be all the information needed to bootstrap a job. Thus there is a separation between the "blueprint for running a job" (in FW spec) and "information about a particular job execution" (in launch object).

I don't think I would mind however having a file called Launch.json (like FW.json) that contains a serialization of the current launch data. Then any code could read the task number locally as well as any other launch-related things (like error message, etc).

Note that there is some effort from people at LBNL to restructure the FireWorks codebase so that Launch and Firework are unified. If this were the case, then the task number could naturally become a part of the Firework itself.

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Best,
Anubhav