[SYSTEMDS-411] Efficient multi-level lineage cache management

This patch improves the handling of multiple cache entries pointing to
the same data (due to multilevel caching).

1) All the entries with the same values are connected with a linkedlist.
Even though they output same data, they have different computation time.

2) Eviction logic marks an entry for deferred spilling/removal if other
 entries are linked to that. If all the entries in a list are marked for
 spilling or removal, only then we evict the item.

3) Disk write and read happen only once for all the items connected to a
 single matrix. This way single read and write restores multiple entries
 to cache and clears more space respectively.

4) Initial experiments show huge improvements in cache management. Now
 the cache can store many more entries (this patch fixes duplicate size
 calculations), need reduced number of disk I/O. These changes overall
 improve cache hit count.

Closes #932.
5 files changed
tree: e3f449b8a6160fac3541c5490563562afa0f3b52
  1. .github/
  2. bin/
  3. conf/
  4. dev/
  5. docker/
  6. scripts/
  7. src/
  8. .gitattributes
  9. .gitignore
  10. CONTRIBUTING.md
  11. LICENSE
  12. NOTICE
  13. pom.xml
  14. README.md
README.md

Apache SystemDS

Overview: SystemDS is a versatile system for the end-to-end data science lifecycle from data integration, cleaning, and feature engineering, over efficient, local and distributed ML model training, to deployment and serving. To this end, we aim to provide a stack of declarative languages with R-like syntax for (1) the different tasks of the data-science lifecycle, and (2) users with different expertise. These high-level scripts are compiled into hybrid execution plans of local, in-memory CPU and GPU operations, as well as distributed operations on Apache Spark. In contrast to existing systems - that either provide homogeneous tensors or 2D Datasets - and in order to serve the entire data science lifecycle, the underlying data model are DataTensors, i.e., tensors (multi-dimensional arrays) whose first dimension may have a heterogeneous and nested schema.

Quick Start Install, Quick Start and Hello World

Documentation: SystemDS Documentation

Python Documentation Python SystemDS Documentation

Status and Build: SystemDS is still in pre-alpha status. The original code base was forked from Apache SystemML 1.2 in September 2018. We will continue to support linear algebra programs over matrices, while replacing the underlying data model and compiler, as well as substantially extending the supported functionalities. Until the first release, you can build your own snapshot via Apache Maven: mvn clean package -P distribution.

Build Documentation Component Test Application Test Function Test Python Test Federated Python Test