Glossary

disco master

Master process that takes care of receiving Disco jobs, scheduling them and distributing tasks to the cluster. There may be many Disco masters running in parallel, as long as they manage separate sets of resources (CPUs).

job

A sequence of the map task and the reduce task. Started by calling the disco.core.Disco.new_job() method.

job functions

Job functions are the functions that the user can specify in disco.job(). Currently, the functions map, reduce, combiner, partitioner are referred as job functions. A job function needs to be a pure function.

pure function

The pure function always evaluates the same result value given the same argument value(s). The function should not depend on any global variables and it must be totally self-contained. In Disco, all job functions must be pure.

See http://en.wikipedia.org/wiki/Pure_function for more information.

task

A Disco job is made of map and reduce tasks. A task consists of many map or reduce instances.