---
id: "bug-1871"
status: "investigating"
status_updated: "2026-09-27"
status_note: "found while soak-verifying the HA group; logs in /home/claude/tmp/xce-ha-final-force-snapshot"
component: "lib"
severity: "unknown"
timestamp: "2026-09-27T07:03:48Z"
last_seen: "2026-09-27T07:03:48Z"
occurrences: 1
files: ["src/lib/netio.c (endpoint_block_tasks/unblock", "handle_input)", "src/controller/ha.c ha_handle_snapshot_chunk"]
tags: ["netio", "epoll", "snapshot", "latency", "ha", "soak"]
related: ["bug-1870"]
legacy: true
gitea_issue: 297
gitea_synced_status: "investigating"
gitea_synced_hash: "e0ba41ca7ee9"
---

# bug-1871: HA snapshot transfer to a rejoining standby stalls mid-stream: primary queues all chunks at once…

## Description
HA snapshot transfer to a rejoining standby stalls mid-stream: primary queues all chunks at once (528KB, 9 chunks); the standby reads a few (1 or 5 of 9 in two runs), its endpoint is unblocked after the last processed chunk, and then no further input event arrives on that connection for 3s+ although the primary has more chunks queued -- --force-snapshot soak's single post-convergence check saw no install (2 of 4 runs, 2026-09-27)

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

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

## Root cause
Not root-caused. Suspect: edge-triggered epoll input + per-endpoint task blocking (netio endpoint_block_tasks): data that arrives while the endpoint is blocked is not re-signalled after endpoint_unblock_tasks, so reading resumes only on the next write from the peer (e.g. the next heartbeat). Likely delays, not loses, the transfer; the soak check was changed to poll 30s.

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

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

## References
- Related: bug-1870
- Gitea: #297