---
id: "bug-466"
status: "fixed"
status_updated: "2026-09-24"
status_note: ""
component: "controller"
severity: "hang"
timestamp: "2026-06-13T01:30:00Z"
last_seen: "2026-09-19T09:00:00Z"
occurrences: 1
files: ["src/controller/config_repl.c"]
tags: ["ha", "iomgr", "deadlock", "config-repl", "api-split", "task-5.2"]
related: ["bug-465"]
legacy: true
---

# bug-466: Unconditional 500ms config barrier wait in push_config_to_standbys reachable from iomgr epoll…

## Description
Unconditional 500ms config barrier wait in push_config_to_standbys reachable from iomgr epoll thread (ha.c raft_cb_become_leader, ha_dispatch_repl_action_for_standby, legacy election path; join.c controller join) -> blocks all controller I/O; the awaited ACK arrives on the blocked thread (structural deadlock)

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

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

## Root cause
task 5.2 made the barrier unconditional inside push_config_to_standbys while best-effort catch-up/election pushes on iomgr-reachable paths still called the same entry

## Fix
Split the API: exported transport-only fan-out push_config_transport_only (no barrier, iomgr-safe) and switched all 5 ha.c sites + join.c:187 to it; push_config_to_standbys (transport+barrier) kept for the vtask-context upgrade path only; doc comments updated in config_repl.h

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

## References
- Related: bug-465