meteor / meteor/react-packages

Double subscriptions when using useTracker in lazy components

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bug in-discussion
Dominant language
JavaScript
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Forks
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Merged PRs (30d)
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Description

When using `useTracker` in lazy components I noticed that sometimes data get subscribed, unsubscribed and subscribed again.

This happens because [useMemo][L122] and [useEffect][L127] sometimes gets called synchronously, thus [comp.stop()][L121] gets called too late, resulting in second subscription.

[L122]: https://github.com/meteor/react-packages/blob/501f0ecfbd694d38f35afde4c96b449b69f8b60e/packages/react-meteor-data/useTracker.ts#L112
[L127]: https://github.com/meteor/react-packages/blob/501f0ecfbd694d38f35afde4c96b449b69f8b60e/packages/react-meteor-data/useTracker.ts#L127
[L121]: https://github.com/meteor/react-packages/blob/501f0ecfbd694d38f35afde4c96b449b69f8b60e/packages/react-meteor-data/useTracker.ts#L121

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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 with packages/react-meteor-data/useTracker.ts, especially the linked useMemo, useEffect, and comp.stop() lines, and reproduce the behavior in a lazy component. Done means preventing the reported duplicate subscribe/unsubscribe/subscribe cycle; the issue names no test to run.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, react
Domain
frontend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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