---
id: "bug-1409"
status: "fixed"
status_updated: "2026-09-24"
status_note: ""
component: "controller"
severity: "hang"
timestamp: "2026-07-04T17:00:00.000Z"
last_seen: "2026-09-19T09:00:00Z"
occurrences: 1
files: ["src/controller/persist.c"]
tags: ["raft-apply-decoupling", "task-6.1", "apply-pump", "busy-loop", "infinite-loop", "commit-resolve-pending", "regression-sweep"]
related: []
legacy: true
---

# bug-1409: test_demotion_convergence hung/spun (18.5M+ log lines, timeout kill) once commit.c's…

## Description
test_demotion_convergence hung/spun (18.5M+ log lines, timeout kill) once commit.c's commit_resolve_pending unconditionally called the new persist_apply_pump_kick

## Environment
_Not recorded (migrated from buglog.json)._

## Reproduction
_Not recorded (migrated from buglog.json)._

## Root cause
apply_pump_drain()'s recheck-then-clear retry loop ignored persist_apply_pump_run()'s return code: on a genuine read failure (e.g. committed_lsn advanced in a test fixture with no real WAL bytes on disk for that LSN, rc=-ENOENT), last_applied_lsn never advances, so the very next re-check inside the SAME drain loop sees identical unresolved work and immediately reclaims the scheduled flag and retries forever -- a tight busy loop with no backoff, hammering disk reads and the logger.

## Fix
apply_pump_drain() now checks persist_apply_pump_run()'s rc immediately after clearing apply_pump_scheduled; a negative rc returns immediately instead of re-checking for more work and reclaiming the flag. The failure is already logged loudly inside persist_apply_pump_run itself. A future, genuinely NEW kick (a later real commit-advance event) retries then, at that event's natural cadence, never in a busy spin.

## Verification
_Not recorded (migrated from buglog.json)._

## References
_Not recorded (migrated from buglog.json)._