db-migrate/node-db-migrate

EventEmitter memory leaks

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#421 opened on Oct 4, 2016

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 (3 comments) (0 reactions) (0 assignees)JavaScript (2,296 stars) (367 forks)batch import
Refactoringgood first issuehelp wanted

Description

When using db-migrate programmatically for multiple databases, warnings are generated for EventEmitter leaks: Warning: Possible EventEmitter memory leak detected. 11 unhandledRejection listeners added.

Adding a unregisterEvents function to api.js should enable programmatic users to get around this. Such a function may also be used more generally to do proper cleanup.

Where registerEvent() is called: https://github.com/db-migrate/node-db-migrate/blob/master/api.js#L136-L147

Where registerEvents() is defined: https://github.com/db-migrate/node-db-migrate/blob/master/api.js#L136-L147

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Contributor guide

Tech stack
javascript
Domain
backenddatabase
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Basic Node.js knowledgeUnderstanding of EventEmitter
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
First, study the existing `registerEvents` function in `api.js` (lines 136-147) to understand how event listeners are added. Then, design an `unregisterEvents` function that removes those listeners. Consider using `removeListener` or `removeAllListeners` for specific events. Finally, implement the function and export it from the module. No existing PR or comments provide a solution, so this is a clean feature addition.