fix: various serverless bug fixes by MasterPtato · Pull Request #4313 · rivet-dev/rivet

MasterPtato · 2026-02-26T01:12:41Z

Description

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Type of change

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected)
This change requires a documentation update

How Has This Been Tested?

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Checklist:

My code follows the style guidelines of this project
I have performed a self-review of my code
I have commented my code, particularly in hard-to-understand areas
I have made corresponding changes to the documentation
My changes generate no new warnings
I have added tests that prove my fix is effective or that my feature works
New and existing unit tests pass locally with my changes

railway-app · 2026-02-26T01:12:50Z

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MasterPtato · 2026-02-26T01:12:56Z

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claude · 2026-02-26T01:18:58Z

PR Review: fix: various serverless bug fixes

Note: This PR is already merged. This review is provided for documentation and retrospective purposes.

Overall a solid set of targeted bug fixes for the serverless actor lifecycle. The changes are well-scoped and address real correctness issues.

Workflow Determinism Fix (`actor/mod.rs`)

Critical fix, well-implemented. Moving util::timestamp::now() out of the workflow loop body and into a GetTs activity is the correct approach. Direct calls to now() inside a workflow are non-deterministic and will diverge on replay. Wrapping it in an activity ensures the result is recorded in workflow history and replayed consistently.

The activity is only called when state.alarm_ts.is_some() via ctx.v(3), which is correct — no need to record a timestamp activity when the result isn't used.

Bug Fix: Wrong Runner Workflow Type (`serverless/conn.rs`)

Real bug fixed. drain_runner was sending runner::Stop (the old MK1 runner workflow signal) when it should have been targeting runner2::Stop. This would have caused serverless runner drains to silently fail on MK2 runners.

Serverless Pool Scale-Down Signal (`actor/runtime.rs`)

The Bump signal when an actor is destroyed or goes to sleep (without being allocated) is the right mechanism to let the pool scale down. The WorkflowNotFound error is handled gracefully with a warning log instead of a hard failure, which is the correct behavior when a runner config has been deleted.

One concern: the same ~27-line block is duplicated across two match arms (the Destroy path and the Sleep path). This is a good candidate for a helper function to prevent the two paths from drifting in the future.

Database Operation Refactoring (`actor/runtime.rs`)

The change from manual key packing + tx.get().is_some() + tx.clear() to tx.with_subspace() + tx.exists() + tx.delete() is cleaner and more idiomatic. No concerns.

`attempted` Field (`runner2.rs`)

The attempted: usize field is added to AllocatePendingActorsOutput with #[serde(default)] for backward compatibility, but searching the codebase shows it is never read by any caller. If this is scaffolding for future observability or telemetry, a short comment would prevent it from being removed as dead code later.

Runner Pool Loop API Migration (`runner_pool.rs`)

The migration from ctx.loope() to ctx.lupe().commit_interval(5).with_state() is straightforward. The commit_interval(5) will reduce checkpoint overhead. The signal buffer reduction from 512 to 256 is fine — 256 is still a large batch size.

Load Test Threshold Removal (`actor-lifecycle.js`)

The removal of http_req_duration thresholds is understandable while active bugs are being addressed. These should be reinstated once the system is stable — otherwise latency regressions won't be caught automatically by the load test.

Load Shedding Defaults (`config/runtime.rs`)

Shifting the default thresholds from 60%/80% to 70%/90% CPU gives the system more headroom before shedding load. Comments and the JSON schema are updated in sync. No concerns.

Summary

Area	Assessment
`GetTs` activity (workflow determinism)	Critical fix, correct
`runner2::Stop` bug fix	Real bug fixed
Serverless `Bump` signal on sleep/destroy	Correct; bump logic should be extracted to avoid duplication
DB `exists`/`delete` refactor	Clean improvement
`attempted` field	Never read by callers; add a comment or use it
`lupe` loop migration	Straightforward
Load test thresholds	Should be re-added once stable

pkg-pr-new · 2026-02-27T00:19:00Z

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commit: 4aa5dca

MasterPtato mentioned this pull request Feb 26, 2026

fix(guard, runner): enforce http body size and ws msg size #4252

Merged

11 tasks

railway-app bot temporarily deployed to rivet-frontend / rivet-pr-4313 February 26, 2026 01:12 Destroyed

This was referenced Feb 26, 2026

fix(epoxy): make quorum sizes match paper #4234

Merged

chore: get docker compose working again #4246

Merged

fix(pegboard): add threshold parameters to runner protocol metadata #4247

Merged

This was referenced Feb 26, 2026

chore: fix tests #4314

Merged

fix(ups): upgrade nats, fix chunking, add chunking tests #4315

Merged

MasterPtato marked this pull request as ready for review February 26, 2026 01:41

MasterPtato requested a review from NathanFlurry February 26, 2026 01:41

MasterPtato mentioned this pull request Feb 26, 2026

chore: add log for runners with no alloc idx #4316

Merged

11 tasks

MasterPtato force-pushed the 02-25-fix_various_serverless_bug_fixes branch from 460c180 to 1f8ab8e Compare February 26, 2026 02:14

MasterPtato force-pushed the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch from e89cab8 to a7065e4 Compare February 26, 2026 02:14

MasterPtato force-pushed the 02-25-fix_various_serverless_bug_fixes branch from 1f8ab8e to ea391b1 Compare February 26, 2026 19:42

MasterPtato force-pushed the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch from a7065e4 to 6df70f8 Compare February 26, 2026 19:42

This was referenced Feb 26, 2026

fix(rivetkit): stall stop handler until start completes #4192

Merged

fix: add serverless leak fix oneoff #4318

Merged

fix: remove useless config params #4319

Merged

fix: always trigger serverless ended early error #4320

Merged

MasterPtato force-pushed the 02-25-fix_various_serverless_bug_fixes branch from ea391b1 to 4aa5dca Compare February 27, 2026 00:12

MasterPtato force-pushed the 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size branch from 6df70f8 to 350c871 Compare February 27, 2026 00:12

NathanFlurry approved these changes Feb 27, 2026

View reviewed changes

Base automatically changed from 02-20-fix_guard_runner_enforce_http_body_size_and_ws_msg_size to main February 27, 2026 00:30

fix: various serverless bug fixes

0a28359

NathanFlurry force-pushed the 02-25-fix_various_serverless_bug_fixes branch from 4aa5dca to 0a28359 Compare February 27, 2026 00:30

railway-app bot temporarily deployed to rivet-frontend / rivet-pr-4313 February 27, 2026 00:30 Destroyed

NathanFlurry merged commit 52cb141 into main Feb 27, 2026
4 of 8 checks passed

NathanFlurry deleted the 02-25-fix_various_serverless_bug_fixes branch February 27, 2026 00:30

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fix: various serverless bug fixes#4313

fix: various serverless bug fixes#4313
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MasterPtato commented Feb 26, 2026

Description

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How Has This Been Tested?

Checklist:

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PR Review: fix: various serverless bug fixes

Workflow Determinism Fix (actor/mod.rs)

Bug Fix: Wrong Runner Workflow Type (serverless/conn.rs)

Serverless Pool Scale-Down Signal (actor/runtime.rs)

Database Operation Refactoring (actor/runtime.rs)

attempted Field (runner2.rs)

Runner Pool Loop API Migration (runner_pool.rs)

Load Test Threshold Removal (actor-lifecycle.js)

Load Shedding Defaults (config/runtime.rs)

Summary

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MasterPtato commented Feb 26, 2026 •

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Workflow Determinism Fix (`actor/mod.rs`)

Bug Fix: Wrong Runner Workflow Type (`serverless/conn.rs`)

Serverless Pool Scale-Down Signal (`actor/runtime.rs`)

Database Operation Refactoring (`actor/runtime.rs`)

`attempted` Field (`runner2.rs`)

Runner Pool Loop API Migration (`runner_pool.rs`)

Load Test Threshold Removal (`actor-lifecycle.js`)

Load Shedding Defaults (`config/runtime.rs`)

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