Dask is a distributed computing library that tightly integrates with the Python ecosystem and allows for multi-core and distributed parallel execution on larger-than-memory datasets. Dask makes it simple to scale up a single machine Python workload to a multi-machine cluster with little or no changes even if the application was never developed with Dask in mind initially.
Dask offers the following:
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Low-level scheduling and execution APIs: Dask provides a set of APIs and facilities for scheduling and parallel execution of task graphs. This execution engine powers the high-level collections mentioned below but can also be used to develop and execute custom, user-defined distributed workloads. These low-level capabilities are an alternative to direct use of
threadingormultiprocessingPython libraries or other task scheduling systems likeLuigiorIPython parallel.For additional information, see Dask delayed and Dask futures.
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High-level distributed libraries: Dask provides distributed equivalents for popular Python collection libraries such as NumPy arrays, Python lists, and Pandas data frames. The Dask equivalents provide API-level compatibility and can be used as drop-in replacement when one needs to work with large datasets. Additionally, Dask provides similar compatibility with scikit-learn and integration with other popular model frameworks to enable scalable training and prediction on large models and datasets.
For additional information, see Dask arrays, Dask dataframes, and Dask ML.
Domino offers the ability to dynamically provision and orchestrate a Dask cluster directly on the infrastructure backing the Domino instance. This allows Domino users to get quick access to Dask without having to rely on their IT team.
When you start a Domino workspace for interactive work or a Domino job for batch processing, Domino will create, manage, and provide a containerized Dask cluster for execution.
See Domino’s quick-start-dask project.
Domino on-demand Dask clusters are suitable for the following workloads:
- Working with large datasets
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Dask excels at scaling up Python data analysis or transformation code where the data that needs to be processed exceeds the resources that can be provided by a single machine. With a compatible API for commonly used Python libraries, Dask is a suitable tool for Python-first data scientists who have R&D Python code for data cleaning, manipulation, and advanced analytics which needs to be scaled to a much larger production dataset. This can be done with minimal modification and without having to switch over to a different ecosystem like Spark.
- Distributed training
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Dask provides a simple drop-in replacement to train parallelizable scikit-learn models at scale. It’s possible to run Dask in single-node and distributed modes to enable parallelization and distribution separately and in conjunction. This approach is an excellent fit for moderate memory footprint models that are CPU/GPU-bound with many individual operations and can be parallelized beyond the limits of a single machine. For larger memory-bound workloads, there are Dask-specific ML libraries (for example, Parallel Meta-estimators and Incremental Hyperparameter Optimizers) that use algorithms; they are specifically optimized to work with the Dask scalable NumPy and DataFrame equivalents.
- Custom distributed computations
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If the available Dask machine learning algorithms or large data representations are insufficient, use the low-level Dask scheduling APIs to build custom algorithms that can benefit from parallelism. Developers control the business logic, while Dask handles task dependencies, network communication, workload resilience, diagnostics, and support functions.