fjd 0.1.2

File-based job distribution for everyone

File-based job distribution. A straightforward pull-model for computational tasks, working with the assumption that all CPUs/cores can access a shared home directory.

Installation

pip install fjd

Usage

Start one or more workers, like this:

recruiter.py hire <number of workers>

These will sit in Unix screen sessions and wait for job assignments.

Then, start a dispatcher:

dispatcher.py

Now the dispatcher waits for jobs in the jobqueue directory. Workers announce themselves in the workerqueue directory, where the dispatcher will find them. (These working directories will be created if they do not yet exist.)

All you have to do now is to put jobs in the queue. You do this by putting a file per job in the jobqueue directory. The file should adhere to the general configuration file standard. Here is an example:

[control] executable: python test/ajob.py logfile: data/job0.dat

[params] param1: value0

Where you specify which command to execute and where results should go.

Your executable (the “job”) gets this configuration file passed as a command line argument. This way, it can see for itself in which logfile to write to.

Take care to get the relative paths correct (or simply make them absolute): If the paths are relative, the path to the executable should be relative to the workers working directory, whereas the path to the logfile should be relative to the jobs working directory.

In addition, you can put other job-specific configuration in there for the executable to see, as I did here in the [params]-section (in fact, only the [control]-section is fjd-specific).

You can see how it all comes together by looking at the simple example in the example directory where there is one script that represents a job and one that creates ten jobs and puts them in the queue.

To run this example, recruit some workers and start a dispatcher. Then, run a script that creates the jobqueue. Finally, observe.

Here are the commands:

$ cd example $ python create_jobs.py $ recruiter.py hire 4 # assuming you have four cores and want to use all of them > [FJD] Hired 4 workers on localhost. $ dispatcher.py > [FJD] Dispatcher started. > Found some jobs to dispatch > Found some jobs to dispatch > Found some jobs to dispatch

It does not matter in which order you do these three things - create jobs, hire workers and dispatch. The workers patiently wait for jobs and the dispatcher waits for jobs.

When jobs are done (the dispatcher will not find new ones quickly), you can “fire” the workers:

$ recruiter.py fire

And you’ll see the results, the log files written by our example jobs:

$ ls data/ job0.dat job2.dat job4.dat job6.dat job8.dat job1.dat job3.dat job5.dat job7.dat job9.dat

(Changes are not tracked yet, too early …)