---
id: "bug-1963"
status: "investigating"
status_updated: "2026-10-10"
status_note: "suspected; confirm with a scheduler fixture test"
component: "scheduler"
severity: "wrong-result"
timestamp: "2026-10-10T10:16:09Z"
last_seen: "2026-10-10T10:16:09Z"
occurrences: 1
files: ["src/scheduler/src/host_iter.c"]
tags: ["scheduler", "host"]
related: []
gitea_issue: 394
gitea_synced_status: "investigating"
gitea_synced_hash: "6f389c3e4c8b"
---

# bug-1963: xce_scheduler host iteration offers unavailable or reconciling hosts as placement candidates

## Description
**Observed:** (source reading; follow-up of the 2026-10-10 P0 fixes (bug-1936..1957))
Suspected (reported by the bug-1939 fix, not verified): `sched_host_iter_next()` (`src/scheduler/src/host_iter.c`) skips admin-closed hosts since bug-1939 but not `XCE_WORKER_UNAVAIL` or `XCE_WORKER_RECONCILING`; other checks (`resource.c:704,887`, `core_session.c:136`) are accounting skips, not placement filters.

**Expected:** Unavailable and reconciling hosts get no new placements.
**Impact:** Possible dispatch to a dead or reconciling host (dispatch then fails and is retried).
**Found by:** follow-up of the 2026-10-10 P0 fixes (bug-1936..1957)
## Environment
- OS: no /etc/os-release; Docker container; NixOS kernel; kernel Linux 6.18.33 x86_64
- libc: glibc 2.42-47 (interpreter /nix/store/wb6rhpznjfczwlwx23zmdrrw74bayxw4-glibc-2.42-47/lib/ld-linux-x86-64.so.2)
- Toolchain: gcc (GCC) 15.2.0, meson 1.9.1
- Build: asan (xce.build)
- Code: scheduler-framework @ 19be145d-dirty
- Deployment: any (found by source reading; confirmed by the RED test of the fix)

## Reproduction
1. Mark a host UNAVAIL in a scheduler fixture and check whether the iterator offers it.
- Frequency: deterministic (by code reading; confirmed by the RED test of the fix)
- Evidence: the code sites quoted in Description; no logs kept.
## Root cause
TODO: required for fixed/partial

## Fix
TODO: required for fixed/partial

## Verification
- Test: TODO: name + file; RED before the fix, GREEN after
- Suites: TODO: suite results and build profile
- Live: TODO: soak/deploy run, or n/a and why

## References
- Related: none