[Wave 9] Add backpressure tests for large cold scans

[truthixify]

Problem

Cold scans can combine parallel RPC ranges and async generators, but there is no regression test proving that a slow consumer does not cause unbounded pending work.

Done when

• Bound concurrent pages and buffered announcements.
• Verify memory stays bounded while consuming slowly.
• Confirm cancellation stops all outstanding requests.
• Add a benchmark and a regression test.

[Peolite1]

@Peolite1 has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

I would love to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Peolite1 to this issue.

[Michael-Olagoke]

@Michael-Olagoke has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

This aligns with my field of expertise. I'm confident I can resolve this issue and deliver satisfactory results

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Michael-Olagoke to this issue.

[joshuasaleh200-spec]

@joshuasaleh200-spec has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hello Maintener, I would love to work on this issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @joshuasaleh200-spec to this issue.

[6tamichael-boop]

@6tamichael-boop has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Based on your requirements, I’ll implement the necessary changes and resolve the issue in line with the design specifications and acceptance criteria. I’m confident I can deliver a clean and reliable solution.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @6tamichael-boop to this issue.

[collinsezedike]

@collinsezedike has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Cold scans combine parallel RPC ranges and async generators, but there is no regression test proving that a slow consumer does not cause unbounded pending work. This absence creates a risk where memory could grow without bound if consumption lags behind production.

Here's my plan:

• Implement backpressure by bounding concurrent pages and buffering announcements
• Verify memory stays bounded while consuming slowly
• Confirm cancellation stops all outstanding requests
• Add a benchmark to measure performance characteristics
• Add a regression test ensuring backpressure protection is maintained

Happy to start as soon as I'm assigned

ℹ️ Repo Maintainers: To accept this application, review their application or assign @collinsezedike to this issue.

[d1a-m3n]

@d1a-m3n has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hello! I have 3+ years of experience. I’d love to contribute to this project by taking on this issue. I’ve read the requirements thoroughly—please assign it to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @d1a-m3n to this issue.

[drips-wave]

Congratulations, @6tamichael-boop! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on September 30, 2026.

🧑‍💻 @6tamichael-boop: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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🌊 Happy Wave 🌊