Why joblib: project goals

Benefits of pipelines

Pipeline processing systems can provide a set of useful features:

Data-flow programming for performance

  • On-demand computing: in pipeline systems such as labView or VTK, calculations are performed as needed by the outputs and only when inputs change.
  • Transparent parallelization: a pipeline topology can be inspected to deduce which operations can be run in parallel (it is equivalent to purely functional programming).

Provenance tracking to understand the code

  • Tracking of data and computations: This enables the reproducibility of a computational experiment.
  • Inspecting data flow: Inspecting intermediate results helps debugging and understanding.

But pipeline frameworks can get in the way

Joblib’s philosophy is to keep the underlying algorithm code unchanged, avoiding framework-style modifications.

Joblib’s approach

Functions are the simplest abstraction used by everyone. Pipeline jobs (or tasks) in Joblib are made of decorated functions.

Tracking of parameters in a meaningful way requires specification of data model. Joblib gives up on that and uses hashing for performance and robustness.

Design choices

  • No dependencies other than Python
  • Robust, well-tested code, at the cost of functionality
  • Fast and suitable for scientific computing on big dataset without changing the original code
  • Only local imports: embed joblib in your code by copying it