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    S3P - 5x to 50x faster than aws-cli

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    S3P provides a radically faster way to copy, list, sync and do other bulk operations over large AWS S3 buckets.

    You can use it as a command-line tool for common operations, or you can use it as a library for nearly anything you can imagine.

    Why is S3P so fast?

    S3's API is structured around listing items in serial - request 1000 items, wait, then request the next 1000. This is how nearly all S3 tools work. S3P, however, can list items in parallel. It leverages S3's ability to request the first 1000 items equal-to or after a given key. Then, with the help of algorithmic bisection and some intelligent heuristics, S3P can scan the contents of a bucket with an arbitrary degree of parallism. In practice, S3P can list buckets up to 15x faster than conventional methods.

    S3P is really just a fancy, really fast, S3 listing tool. Summarizing, copying and synching are all boosted by S3P's core ability to list objects radically faster.

    We've sustained copy speeds up to 8gigabytes/second between two buckets in the same region using a single EC2 instance to run S3P.

    S3P Blog Post

    Read more about S3P on Medium.


    1. NodeJS

    2. AWS-CLI

      The aws-cli is required for copying large files. By default, files larger than 100 megabytes are copied with aws-cli. This is a good compromise for performance. However, you can change that threshold to 5 gigabytes with the --large-copy-threshold option.

      Why? The aws-sdk does not support coping files larger than 5 gigabytes without a much more complicated solution.

    3. Key names must use a limited character set:


      Why? Since Aws-S3 doesn't support listing Keys in descending order, S3P uses a character-range-based divide-and-conquer algorithm.

    AWS Credentials

    s3p uses the same credentials aws-cli uses, so see their documentation:


    There is no need to install s3p directly. As long as you have NodeJS installed, you can run s3p directly using npx.

    The built in help details all the commands, options, and provides many examples:

    # list commands and get overall help
    npx s3p help

    Use the --help option for detailed help and examples for each command:

    # get specific command help and example uses
    npx s3p cp --help

    Install NPM Package

    You can also install s3p locally which will allow it to run faster.

    # install s3p on your current machine
    npm install s3p -g
    # now it runs from the local install:
    npx s3p help


    In addition to performance, S3P provides flexible options for custom list, copying and comparing:

    • Only list files with a matching prefix, starting-after a given key, and/or stopping-at a given key. These options are very fast; the rest of the bucket not matching these criteria is ignored completely.
    • Filter source files with arbitrary JavaScript. Further filter every file listed arbitrarily based on Key, Size, or Date. This is slower, since every file must be filtered in JavaScript but none-the-less, quite useful.
    • When copying, syncing or comparing, re-key files by replacing prefixes, adding prefixes, or with an arbitrary JavaScript function.


    Surprisingly, you don't even need to run S3P in the cloud to see much of its benefits. You can run it on your local machine and, since S3 copying never goes directly through S3P, it doesn't use up any AWS bandwidth.

    S3-bucket-listing performance can hit almost 20,000 items per second.

    S3-bucket-copying performance can exceed 8 gigabytes per second.

    Yes, I've seen 9 gigabytes per second sustained! This was on a bucket with an average file size slightly larger than 100 megabytes. S3P was running on a single c5.2xlarge instance. By comparison, I've never seen aws-s3-cp get more than 150mB/s. That's over 53x faster.

    The average file-size has a big impact on s3p's overall bytes-per-second:

    location command aws-cli s3p speedup average size
    local ls 2000 items/s 20000 items/s 10x n/a
    local cp 30 mB/s 150 mB/s 5x 512 kB
    ec2 cp 150 mB/s 8 gB/s 54x 100 mB

    S3P was developed to operate on buckets with millions of items and 100s of terabytes. Currently, S3P is still only a single-core NODE application. There are opportunities for even more massively parallel S3 operations by forking workers or even distributing the work across instances with something like Elastic-Queue. If someone needs solutions that are 100-1000x faster than aws-cli, let us know. We'd love to work with you.


    All the documentation is embedded in the CLI help pages. Use:

    # get a list of commands
    npx s3p help
    # get a list of options for a command
    # example:
    npx s3p cp --help


    All the capabilities of the CLI are also available as an API. To learn the API, first learn the CLI options, and then, to learn the API call for a specific CLI command, run that command on the command-line with the --api-example option. This will output example JavaScript code for invoking that command programmatically.

    NOTE: When you use --api-example on the command-line, your command won't actually run. S3P will only output the JavaScript equivalent of the CLI command to the console and then quit.



    > npx s3p ls --bucket foo --quiet --api-example


       bucket: "foo",
       quiet: true
    // > Promise

    Test run:

    > node


       bucket: "foo",
       quiet: true
    }).then((out) => console.log(out));


      "bucket-a-name": creationDateA,
      "bucket-b-name": creationDateB


    S3P was originally developed by in conjunction with Resolution Bioscience, Inc.

    GenUI is a technology commercialization software consultancy based in Seattle. We accelerate software roadmaps. Please feel free to contact GenUI and tell us about your project. We'd love to hear from you.




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    • shanebdavis