mosaicml / mosaicml/streaming

Support large size index.json (20GB +)

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#662 2 comments 0 reactions 0 assignees View on GitHub

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enhancement
Dominant language
Python
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Forks
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Description

🚀 Feature Request

Large index.json are slow to load. Currently, I am trying to increase shard size, so stream.py#L473 will be faster (hopefully).

Motivation

These two steps are very slow for large index.json files.

https://github.com/mosaicml/streaming/blob/main/streaming/base/stream.py#L461

and

https://github.com/mosaicml/streaming/blob/main/streaming/base/stream.py#L473

especially with large scale dataset (e.g, Billion same).

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading streaming/base/stream.py around lines 461 and 473 and measure which index.json operations become slow at 20GB or larger. Define a streaming or sharding approach that avoids the current bottleneck, then verify that large index.json files can be processed efficiently without changing the dataset behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
data-engineering
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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