Reduce memory churn by not calling shrink_to_fit

[greenscientist]

On an high thread count, we are getting contention on memory by constantly allocating and deallocating memory. We can save some of that by not calling shrink_to_fit. We might use a bit more memory, but gain on performance

Summary by CodeRabbit

• Refactor
  • Adjusted memory management strategy to reduce explicit memory capacity releases during data resets and cache operations.

[coderabbitai]

Walkthrough

The PR removes three calls to shrink_to_fit() across three source files. In resets.cpp, two calls are removed from accessFootpaths and egressFootpaths after clearing. In transit_data.cpp, two calls are removed from forwardConnections and reverseConnections after populating. In trips_and_connections_cache_fetcher.cpp, one call is removed from the connections vector after clearing. No control flow, error handling, or logic is altered; only explicit memory capacity reduction is affected.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: removing shrink_to_fit() calls to reduce memory churn, which aligns with all modifications across the three files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[greenscientist]

We might need to benchmark this a bit more

[cubic-dev-ai]

No issues found across 3 files

[tahini]

As-tu roulé les benchmarks sur cette PR?

[greenscientist]

As-tu roulé les benchmarks sur cette PR?

Il faut que j'en refasse, maintenant qu'on a identifié le bottleneck to dispatch http.

[tahini]

Putting a request changes to not merge accidentally until we know what the benchmarks say and confirm it is needed