v3: prevent envs with excess queues from degrading dequeue performance

[ericallam]

Summary by CodeRabbit

• New Features
  • Introduced a configurable limit for the maximum number of queues processed per environment.
• Bug Fixes
  • Ensured correct selection and distribution of queues when the maximum per environment is set.
• Tests
  • Added comprehensive tests to verify queue limiting and fair distribution across environments.

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Latest commit: b0112fd

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[coderabbitai]

Walkthrough

A new environment variable, MARQS_MAXIMUM_QUEUE_PER_ENV_COUNT, was introduced to configure the maximum number of queues processed per environment. This variable is incorporated into the environment schema and passed into the FairDequeuingStrategy as an optional configuration parameter. The queue ordering logic within the strategy now respects this limit, slicing the list of queues per environment to the specified maximum. Additional telemetry was added to trace when the parent queue limit is reached. Comprehensive tests were added to validate the correct enforcement of this new limit under various scenarios.

Changes

File(s)	Change Summary
apps/webapp/app/env.server.ts	Added MARQS_MAXIMUM_QUEUE_PER_ENV_COUNT to the environment schema with a default value of 50.
apps/webapp/app/v3/marqs/fairDequeuingStrategy.server.ts	Added maximumQueuePerEnvCount option to FairDequeuingStrategyOptions. Updated queue ordering logic to enforce this limit. Added tracing attribute when parent queue limit is hit.
apps/webapp/app/v3/marqs/index.server.ts	Passed the new environment variable to the FairDequeuingStrategy instantiation in getMarQSClient.
apps/webapp/test/fairDequeuingStrategy.test.ts	Added multiple new tests covering the enforcement and behavior of maximumQueuePerEnvCount in various scenarios, including fairness, edge cases, and statistical distribution checks.

Sequence Diagram(s)

sequenceDiagram
    participant Env as Environment
    participant MarQS as FairDequeuingStrategy
    participant Test as Test Suite

    Env->>MarQS: Provide MARQS_MAXIMUM_QUEUE_PER_ENV_COUNT
    MarQS->>MarQS: Limit queues per environment to maximum
    MarQS->>Test: Return selected queues per environment
    Test->>Test: Assert queue counts and distribution

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Suggested reviewers

• matt-aitken
• nicktrn

Poem

In the warren where queues align,
A new limit keeps them in line.
Fifty per burrow, no more in the den,
Fairness enforced by code and by pen.
Tests hop around, statistics in tow,
Ensuring the queues all get their go.
🐇✨

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between bb606a1 and b0112fd.

📒 Files selected for processing (4)

• apps/webapp/app/env.server.ts (1 hunks)
• apps/webapp/app/v3/marqs/fairDequeuingStrategy.server.ts (3 hunks)
• apps/webapp/app/v3/marqs/index.server.ts (1 hunks)
• apps/webapp/test/fairDequeuingStrategy.test.ts (1 hunks)

🧰 Additional context used

🧬 Code Graph Analysis (2)

apps/webapp/app/v3/marqs/index.server.ts (1)

apps/webapp/app/env.server.ts (1)

• env (721-721)

apps/webapp/test/fairDequeuingStrategy.test.ts (4)

internal-packages/testcontainers/src/index.ts (1)

• redisTest (128-128)

apps/webapp/test/utils/marqs.ts (3)

• setupConcurrency (57-88)
• setupQueue (33-46)
• calculateStandardDeviation (98-116)

apps/webapp/app/v3/marqs/fairDequeuingStrategy.server.ts (3)

• FairDequeuingStrategy (89-579)
• queues (255-303)
• queues (428-472)

apps/webapp/app/v3/marqs/constants.server.ts (1)

• MARQS_RESUME_PRIORITY_TIMESTAMP_OFFSET (1-1)

⏰ Context from checks skipped due to timeout of 90000ms (7)

• GitHub Check: e2e / 🧪 CLI v3 tests (windows-latest - pnpm)
• GitHub Check: e2e / 🧪 CLI v3 tests (windows-latest - npm)
• GitHub Check: e2e / 🧪 CLI v3 tests (ubuntu-latest - pnpm)
• GitHub Check: e2e / 🧪 CLI v3 tests (ubuntu-latest - npm)
• GitHub Check: units / 🧪 Unit Tests
• GitHub Check: typecheck / typecheck
• GitHub Check: Analyze (javascript-typescript)

🔇 Additional comments (10)

apps/webapp/app/env.server.ts (1)

387-387: LGTM! Clean addition of environment variable.

The new environment variable MARQS_MAXIMUM_QUEUE_PER_ENV_COUNT with a default value of 50 looks good. The implementation follows the established pattern for environment variables in this file.

apps/webapp/app/v3/marqs/index.server.ts (1)

2192-2192: Well-integrated configuration usage.

The new maximumQueuePerEnvCount parameter is correctly passed to the FairDequeuingStrategy instance from the environment configuration. I notice it's applied to the queuePriorityStrategy but not to the envQueuePriorityStrategy, which aligns with the PR's goal of limiting queues at the parent queue level only.

apps/webapp/app/v3/marqs/fairDequeuingStrategy.server.ts (3)

46-50: Well-documented option.

The option type definition is clear with helpful JSDoc explaining its purpose.

---

238-241: Clean implementation of queue count limiting.

The implementation is straightforward and effective - if maximumQueuePerEnvCount is set, it simply slices the array of ordered queues to that maximum before mapping them to queue IDs. This ensures only the most relevant queues (based on the strategy's ordering) are included.

---

524-526: Good telemetry addition.

Adding the parent_queue_limit_reached attribute to the span is a smart addition that will help with monitoring and troubleshooting when the system is hitting its configured limits.

apps/webapp/test/fairDequeuingStrategy.test.ts (5)

1036-1121: Good basic test for queue limit enforcement.

This test effectively verifies that the strategy respects the maximumQueuePerEnvCount parameter and selects the appropriate queues (the oldest ones) when applying the limit.

---

1123-1237: Excellent fairness distribution test.

This is a thorough test that verifies the randomization behavior over a large number of iterations to ensure that while enforcing a limit, all queues still have a chance to be selected over time. The statistics collection and standard deviation checking provide strong validation of the fairness characteristics.

---

1239-1304: Good edge case testing.

Testing the scenario where the limit is larger than the available queues is important to ensure the system doesn't break when configured with generous limits.

---

1306-1368: Thorough empty environment handling test.

Testing the edge case of environments with no queues is important for robustness. The test confirms that empty environments are properly handled and don't affect the processing of environments that do have queues.

---

1370-1459: Comprehensive priority queue interaction test.

This test thoroughly validates that the queue limit respects priority offsets while still providing a reasonable distribution. The statistical analysis of selection percentages and standard deviation provides strong evidence that the system behaves as expected even with the complexity of priority queues.

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• 📝 Generate Docstrings

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