Thyme: dispatch jobs using RabbitMQ

Thyme is a set of Python scripts that use RabbitMQ as intermediary for submitting and running jobs.

• Jobs are submitted to RabbitMQ using the condor_submit command.
• The thyme_worker command fetches one job from RabbitMQ, executes it and exits.

Condor-like interface for AliEn

AliEn is the Grid middleware in use by the ALICE experiment at CERN. It works by continuously submitting pilot jobs on your local batch system: when pilots run they connect to the AliEn central services to fetch the actual job.

AliEn features different connectors to communicate with a variety of batch systems. Thyme piggybacks on the HTCondor interface: the shipped condor_q and condor_submit commands behave the way AliEn expects them to do. It is therefore possible to use Thyme on a site configured as HTCondor without modifying AliEn's code.

Made for pilot jobs

The Thyme worker was specifically designed to run pilot jobs inside one-time containers at scale. Scalability is provided by RabbitMQ. Thyme does not perform any cleanup of the working area as it assumes that somebody else (like Docker) will take care of it.

As a matter of fact Thyme was designed to be run in containers spawned by Plancton.

Thyme is fully stateless. Jobs in the queue might be lost and no recovery option is available. Once a job is fetched from the queue it is gone, and there is no way to know how many jobs were fetched and are running. Those features are typical of batch systems and were not implemented as we do not need them in many cases (such as AliEn).

Try it locally

You can try it locally with Docker Compose. Bring up the cluster:

docker-compose up

You can submit jobs with:

docker-compose scale condor_submit=<N>

where <N> is the number of jobs to submit. You can scale the workers (the ones fetching and running the jobs) by using:

docker-compose scale worker=<N>