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This repository was archived by the owner on Aug 7, 2025. It is now read-only.

add(kinesis): Include new Scala engine and performance section #1786

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HarshCasper merged 5 commits into main from kinesis/performance-section
Jun 7, 2025

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@gregfurman
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@gregfurman gregfurman commented Jun 5, 2025

Motivation

Document the newly introduced Kinesis Mock Scala engine in addition to a small section on performance tuning of the Kinesis service.

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@gregfurman gregfurman self-assigned this Jun 5, 2025
@gregfurman gregfurman added the documentation Improvements or additions to documentation label Jun 5, 2025
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🎊 PR Preview has been successfully built and deployed to https://localstack-docs-preview-pr-1786.surge.sh 🎊

@gregfurman gregfurman marked this pull request as ready for review June 5, 2025 12:10
@localstack localstack deleted a comment Jun 5, 2025
@localstack localstack deleted a comment Jun 5, 2025
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lgtm after adding the config to our global reference


| Variable | Description |
| -------- | ----------- |
| `KINESIS_MOCK_PROVIDER_ENGINE` | String value of `node` (default) or `scala` that determines the underlying build of Kinesis Mock. [^scala-future] |
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@joe4dev joe4dev Jun 5, 2025

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suggestion: Can we add the configuration to the global LocalStack configuration page: https://docs.localstack.cloud/references/configuration/#kinesis

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@HarshCasper HarshCasper Jun 5, 2025

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Done!

| Variable | Description |
| -------- | ----------- |
| `KINESIS_MOCK_PROVIDER_ENGINE` | String value of `node` (default) or `scala` that determines the underlying build of Kinesis Mock. [^scala-future] |
| `KINESIS_MOCK_MAXIMUM_HEAP_SIZE` | JVM memory format string (default: `512m`) that sets the maximum memory size for the Kinesis Mock Scala server, corresponds to the JVM `-Xmx` flag. [^scala] |
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@joe4dev joe4dev Jun 5, 2025

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praise: great clarity explaining what happens under the hood 👍

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@HarshCasper HarshCasper Jun 5, 2025

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FYI – I have removed this section and added a redirect to the config docs. Right now, all config vars for individual services are documented there but this can change in future.

- Reduce `KINESIS_LATENCY` artificial response delays from the default `500` milliseconds (or disable entirely with `0`).

[^scala]: This feature is only available in the more performant Scala Kinesis Mock build that can be toggled by setting `KINESIS_MOCK_PROVIDER_ENGINE=scala`.
[^scala-future]: Future versions of LocalStack will likely default to using the `scala` engine over the less-performant `node` version currently in use.
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@joe4dev joe4dev Jun 5, 2025

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question: Are we aware of any limitations worth mentioning? If not, it might be worth mentioning that we are unaware of any limitations and encourage users to raise a GH issue if they encounter any challenges.

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@gregfurman gregfurman Jun 5, 2025

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Other than the potential for higher memory overhead (since we pre-allocate 256m by default to the JVM) I'm not sure I can think of any

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@joe4dev joe4dev Jun 5, 2025

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Ok, then let's be transparent and add that explicitly 👍

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@HarshCasper HarshCasper merged commit 7bd1702 into main Jun 7, 2025
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@HarshCasper HarshCasper deleted the kinesis/performance-section branch June 7, 2025 13:34
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@joe4dev joe4dev joe4dev approved these changes

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