Tracking an output file during execution

You can track the last few lines of file during Firework execution. For example, you can monitor an output file to make sure the run is progressing as expected. Setting one or more such trackers is simple.

Adding a tracker (via files)

To add a tracker, set a key called _tracker in your fw_spec to be an array of objects with filename and nlines keys. Each tracker will track the desired number of final lines of a particular file. The example below has two trackers, one for inputs.txt and another for words.txt (see the _trackers section at the bottom):

name: Tracker FW
  - _fw_name: TemplateWriterTask
      opt1: 5.0
      opt2: fast method
    output_file: inputs.txt
    template_file: simple_template.txt
  - _fw_name: ScriptTask
    script: wc -w < inputs.txt > words.txt
    use_shell: true
  - filename: words.txt
    nlines: 25
  - filename: inputs.txt
    nlines: 25

You can see this example in <INSTALL_DIR>/fw_tutorials/tracker.

Adding a tracker (via code)

The following code example creates the Firework above with two trackers:

from fireworks import Firework, Tracker, ScriptTask, TemplateWriterTask

# create the Firework consisting of multiple tasks
firetask1 = TemplateWriterTask({'context': {'opt1': 5.0, 'opt2': 'fast method'}, 'template_file': 'simple_template.txt', 'output_file': 'inputs.txt'})
firetask2 = ScriptTask.from_str('wc -w < inputs.txt > words.txt')
# define the trackers
tracker1 = Tracker('words.txt', nlines=25)
tracker2 = Tracker('inputs.txt', nlines=25)
fw = Firework([firetask1, firetask2], spec={"_trackers": [tracker1, tracker2]})


Viewing the tracked file

You can view the tracked files for all FireWorks (during or after execution) with the command:

lpad track_fws

which will print out data like:

# FW id: 1
## Launch id: 1
### Filename: words.txt
### Filename: inputs.txt
option1 = 5.0
option2 = fast method

Choosing the Firework(s) for which to view the tracked files

Besides for the <FW_ID>, there are additional options for specifying the Firework(s) that you want to get the tracked data for. For example, you can search for the tracker data of a particular Firework id or of all FIZZLED FireWorks via:

lpad track_fws -i <FW_ID>
lpad track_fws -s FIZZLED

Type lpad track_fws -h to see all the options, including advanced queries.

Choosing the tracked files to display

The --include (or -c) and --exclude (or -x) options can be used to filter what files are displayed in the Tracker Report. The --include option means to only display those files, whereas the --exclude option means to filter out those files from the report:

lpad track_fws --include words.txt
lpad track_fws --exclude words.txt

You can separate multiple filenames by spaces.

Frequency of monitoring

The output file is monitored for changes at every update ping interval, as well as at the beginning and completion of execution. By default, the ping interval is set to be every hour; this is to avoid overloading the database with pings if tens of thousands of runs are happening simultaneously. You can change the ping interval (PING_TIME_SECS) in the FW config.

A note about nlines

The tracker is meant to give basic debug information about a job, not to permanently store output files. There is a limit of 1000 lines to keep the Mongo document size reasonable, and to keep FireWorks performing well. We suggest you leave nlines to be less than 100 lines and only use this feature for basic debugging.