KROWKEE: A Distributed Multi-Stream Data Sketching Toolkit.

This repository implements krowkee, a toolkit for scalably and efficiently summarizing many data streams in distributed memory. krowkee is intended for applications involving where one needs to summarize huge loosely structured data, such as matrices or graphs, where individual components such as rows/columns or vertex adjacency information are impractical to store and directly inspect. krowkee ingests these objects as data streams - unstructured, arbitrarily ordered lists of updates - and accumulates summaries thereof in the form of data sketches.

Although there are many types of data sketches, the practical varieties encompassed by krowkee have many advantages compared to directly observing data:

• approximation guarantees on some stream statistic
• merge operator
• worst-case logarithmic memory usage
• ... and many even support sparse storage

krowkee currently supports only sparse subspace embeddings to perform randomized and fast dimensionality reduction. Future sketch support is planned, principally including cardinality sketches such as the HyperLogLog.

Getting started

Reqirements

• C++17 - GCC verions 8-11 are tested. Your mileage may vary with other compilers.
• Optional dependencies:
  • YGM 0.3 or greater for distributed memory communication. Toggle with CMake option KROWKEE_USE_YGM. Default ON. If package ygm is not installed, krowkee will attempt to clone and install via FetchContent. Includes additional dependencies:
    • Cereal - C++ serialization library. If package cereal is not installed, krowkee will attempt FetchContent.
    • MPI
  • Boost 1.48 or greater for boost::container::flatmap. Toggle with CMake option KROWKEE_USE_BOOST. Default ON.

Using krowkee with CMake

krowkee is a header-only library that is simple to incorporate into dependent projects using CMake. Add the following to your CMakeLists.txt to "find-else-fetch" krowkee, cloning it and its dependencies and preparing their headers for installation as a part of your project.

set(DESIRED_KROWKEE_VERSION 0.1)
find_package(krowkee ${DESIRED_KROWKEE_VERSION} CONFIG)
if (NOT krowkee_FOUND)
    FetchContent_Declare(
        krowkee
        GIT_REPOSITORY https://github.com/LLNL/krowkee
        GIT_TAG v${DESIRED_KROWKEE_VERSION}
    )
    FetchContent_GetProperties(krowkee)
    if (krowkee_POPULATED)
        message(STATUS "Found already populated krowkee dependency: "
                       ${krowkee_SOURCE_DIR}
        )
    else ()
        set(JUST_INSTALL_KROWKEE ON)
        set(KROWKEE_INSTALL ON)
        set(KROWKEE_USE_YGM ON)  # or OFF if local-only
        FetchContent_Populate(krowkee)
        add_subdirectory(${krowkee_SOURCE_DIR} ${krowkee_BINARY_DIR})
        message(STATUS "Cloned krowkee dependency " ${krowkee_SOURCE_DIR})
    endif ()
else ()
    message(STATUS "Found installed krowkee dependency " ${krowkee_DIR})
endif ()

Building

These instructions assume that you have a relatively modern C++ compiler (C++17 required, only tested using GCC). If included, krowkee's CMake build makes use of find-else-fetch semantics for its ygm and cereal dependencies. krowkee will try to find local installations of the libraries, and will clone and link the repositories internally if none are found.

One can build a local-only version of krowkee by passing to cmake .. -DKROWKEE_USE_YGM=OFF.

spack is a convenient means to include cereal and manage compilers, but is not required to build krowkee.

Build steps

Clone the project and make the build directory

$ git clone ssh://git@czgitlab.llnl.gov:7999/krowkee/krowkee.git
$ mkdir krowkee/build
$ cd krowkee/build

Option 1: use spack

$ spack load gcc     # tested at >=8.3.1.
$ spack load boost   # optional, at least version 1.75
$ spack load cereal  # optional, at least version 1.3.0

Option 2: use module

$ module load gcc/8.3.1  # or desired gcc version

Build krowkee.

$ cmake ..
$ make

Alternately, we can build the local-only version of krowkee which will not use ygm, cereal, or MPI.

$ cmake .. -DKROWKEE_USE_YGM=OFF
$ make

Installation

krowkee build system supports local installation of it and all dependent header-only libraries (ygm and cereal) via make install. If operating on a system without write permissions to CMake's default installtion locations, set the CMAKE_INSTALL PREFIX:

$ export CMAKE_USER_INSTALL_PREFIX='/desired/install/path'
$ cmake .. -DCMAKE_INSTALL_PREFIX=${CMAKE_USER_INSTALL_PREFIX}
$ make
$ make install

It is most likely worth setting this CMAKE_USER_INSTALL_PREFIX and adding it to your CMAKE_PREFIX_PATH in your .profile, .bashrc, or equivalent.

Testing

It is easy to run all test cases once krowkee is built by running

make test

Alternately, one can directly run individual test cases with more options and verbose outputs, e.g.

$ ./test/SEQ_local_linearsketch_test

All tests support an -h flag listing options.

About

Authors

• Benjamin W. Priest (priest2 at llnl dot gov)
• Alec Dunton (dunton1 at llnl dot gov)

License

krowkee is distributed under the MIT license.

All new contributions must be made under the MIT license.

See LICENSE-MIT, NOTICE, and COPYRIGHT for details.

SPDX-License-Identifier: MIT

Release

LLNL-CODE-827987