Managing multiple actions

Overview

This section explains that directories have a status for each action and how those statuses are determined given the products and previous_actions properties.

Summarizing the workflow's status

Each directory in the workspace has a status for each action in the workflow. Continuing with the hello-workspace example from the previous section, execute:

row show status

to see a summary. You should see:

Action Completed Submitted Eligible Waiting Remaining cost
hello          0         0        3       0    3 CPU-hours

Products and previous actions

Wait. Why are there 3 eligible directories for hello? Didn't we already execute that action? Yes, but the action defines no products. Products are files that an action creates in a directory. Row considers an action complete when all products are present in a given directory.

Replace the contents of workflow.toml with:

[[action]]
name = "hello"
command = 'echo "Hello, {directory}!" | tee workspace/{directory}/hello.out'
products = ["hello.out"]

[[action]]
name = "goodbye"
command = 'echo "Goodbye, {directory}!"'
previous_actions = ["hello"]

This file changes the hello action's command to: echo "Hello, {directory}!" | tee workspace/{directory}/hello.out and sets its products to ["hello.out"]. tee writes its input both to the given file and the terminal, so these two changes together 1) Write hello.out into the directory and 2) Instruct row that the action is complete when hello.out is present.

The new goodbye action is much like the original hello except that it sets previous_actions = ["hello"]. This line tells row that hello must be complete before goodbye may be executed in a given directory.

Execute:

row show status

again and you should now see that hello is still eligible:

Action  Completed Submitted Eligible Waiting Remaining cost
hello           0         0        3       0    3 CPU-hours
goodbye         0         0        0       3    3 CPU-hours

goodbye is waiting because its previous actions are not complete.

Now, submit eligible jobs on directory1: Execute:

row submit directory1

Run row show status and see if the output is what you expect.

Getting more detailed information

row show status shows you the number of directories in each state. Sometimes you want to know about specific directories. Execute:

row show directories --action hello

to see the details of each directory with respect to the hello action. You should see:

Directory  Status
directory0 eligible
directory1 completed
directory2 eligible

directory1 is complete while the others remain eligible. This means that directory1 should now be eligible for the goodbye action. You now know two ways to find this out. Try them and see!

Next, submit the goodbye action:

row submit --action goodbye

and you should see:

[1/1] Submitting action 'goodbye' on directory directory1 (0 seconds).
Goodbye, directory1!

Next steps

Now you know how to create workflows with multiple actions, control when row considers an action complete on a directory, and prevent an action from running until all previous actions have completed a directory first. The next section will explain how to associate arbitrary data with each directory and use that to form groups.

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