Files
multi-agent-mux/.agents/skills/lib_py/delegation/heartbeat.py
T
GodopuandClaude Opus 5 135d76f903 fix(issue-18): admit remote attempts atomically, end timed-out commands with their group, fence heartbeats off the terminal, renew liveness only on news
Review round 2 (planner-reviewer-codex-01, NOT PASS at d09c162):

- R1 remote.mirror_job: admission under the registry lock. The same
  dispatch_token is idempotent (a finished attempt never runs again), a
  lower attempt or the same attempt under another token is refused before
  any write, and only a strictly newer attempt replaces the record
  (register_job(supersede_older_attempt=True); events.log kept, seqs stay
  monotonic).
- R2 remote.handle_dispatch: the --exec command runs in its own session;
  at timeout_sec, or when the runner is interrupted (SIGTERM now unwinds
  it), the whole process group is terminated (TERM, then KILL) before the
  error is published.
- R3 terminal barrier: a terminal publish raises an attempt-scoped barrier
  under the lock that allocates seqs, stops the heartbeat timer, gives it
  MAM_HEARTBEAT_DRAIN_S (default 1 s) to exit and then kills it, and only
  then takes its own seq. Beats are admitted under that lock
  (next_seq(admit=...)); a beat still on the wire is cancelled with the
  timer rather than holding the terminal back; and a late non-terminal
  event never publishes a running state over a terminal record.
- R4 job_subscriber: a retained state renews the idle clock only when its
  seq is newer than everything already accepted; re-delivered or older
  snapshots still recover a terminal status.
- tests: five regressions, all failing on 77f2829; T1-14's wall clock
  15 -> 30 s against public-broker latency.
- docs: MESSAGING 2.5 (barrier, state renewal, detection vs final close),
  heartbeat docstring, loop SKILL.md (remote rows need the Python runner),
  VERSIONS v4.5.0 items 1/4/5 and the test count (25).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HCGpJXhSZasJLU38ksDghe
2026-09-13 20:49:56 +09:00

416 lines
17 KiB
Python

"""heartbeat.py — the agent-side automatic heartbeat timer (Issue #18).
The liveness contract obliges an agent to publish `progress` at least every N
seconds while it works. Relying on the brief to say so meant an agent that
forgot, or one whose turn was one long tool call, was closed as unresponsive
while it was fine. This timer publishes the heartbeat for it.
`publish_event.py --event started --heartbeat N` starts one detached timer per
job; it runs in its own session so the agent's shell may return at once. The
timer stops on its own when
* the job record reaches a terminal status (completed / error / cancelled),
* the record's dispatch_token or attempt_id changes (the job was
re-dispatched: this attempt's heartbeats would be refused anyway),
* the job record disappears, or
* its lifetime exceeds the job's wall-clock timeout plus one period.
A terminal publish also stops it directly, so no heartbeat can trail a
`completed` (review round 2, codex R3): it raises an attempt-scoped barrier
under the registry lock that allocates seqs (a beat either took its seq before
it or is refused when it asks for one), stops the timer through the pidfile
(`<registry>/<job_id>.heartbeat.pid`), and waits for the timer to drain its
in-flight beats - killing it after `MAM_HEARTBEAT_DRAIN_S` - before it takes
its own seq.
The timer is bound to the agent's life (review B2): it watches one process -
`--watch-pid`, or by default the nearest ancestor of the publishing process
that is an agent CLI (claude, codex, agy, ...; the agent runs the start
command from its shell tool, so that ancestor is the agent itself) - and stops
within one period once that process is gone. A crashed or killed agent
therefore stops heartbeating and is closed after K x N like any silent one;
an agent that is alive but stuck keeps heartbeating, which is the contract's
deliberate trade-off (liveness of the process, not of the work).
Each beat is an ordinary `publish_event` call in this process: it takes the
next seq, is signed with the job's auth_token, carries the dispatch token and
attempt id the timer was started with, and is recorded in events.log before
the wire publish - exactly what the orchestrator's disk and wire liveness
checks read.
"""
from __future__ import annotations
import argparse
import json
import logging
import os
import signal
import subprocess
import sys
import threading
import time
from typing import List, Optional
from lib_py.delegation import mqtt_common
from lib_py.delegation.mqtt_common import default_registry_dir, load_job
logger = logging.getLogger("delegate_job.heartbeat")
TERMINAL_STATUSES = ("completed", "error", "cancelled")
HEARTBEAT_DETAIL = "heartbeat"
MAX_IN_FLIGHT = 8
# The agent CLIs, as lib_py.agents.base names them. Repeated here rather than
# imported: lib_py.delegation may not import a sibling lib_py package (a
# frozen loop binds delegation to a different tree, see __init__).
AGENT_CLI_NAMES = ("claude", "agy", "hermes", "grok", "opencode", "codex")
def _is_agent_cli(command: str) -> bool:
"""Some token before the first option has an agent basename
(`claude ...`, `node .../claude ...`, `/bin/sh .../agy ...`)."""
for tok in command.split():
if tok.startswith("-"):
break
if os.path.basename(tok) in AGENT_CLI_NAMES:
return True
return False
def _process_table():
"""{pid: (ppid, command)} from ps; empty when ps is unavailable."""
try:
out = subprocess.run(["ps", "-axo", "pid=,ppid=,command="], capture_output=True, text=True).stdout
except OSError:
return {}
table = {}
for line in out.splitlines():
parts = line.split(None, 2)
if len(parts) < 2:
continue
try:
pid, ppid = int(parts[0]), int(parts[1])
except ValueError:
continue
table[pid] = (ppid, parts[2] if len(parts) > 2 else "")
return table
def nearest_agent_cli_ancestor(start_pid: Optional[int] = None) -> Optional[int]:
"""PID of the closest ancestor (start_pid included) that is an agent CLI.
The agent executes the injected start command through its shell tool, so
the chain is agent CLI -> shell -> python publish_event; the agent is the
first agent-CLI process met walking up. None when there is no such
ancestor (a test, a plain shell, a remote runner)."""
table = _process_table()
pid = start_pid if start_pid is not None else os.getpid()
seen = set()
while pid and pid > 1 and pid not in seen:
seen.add(pid)
entry = table.get(pid)
if entry is None:
return None
ppid, command = entry
if _is_agent_cli(command):
return pid
pid = ppid
return None
def pidfile_path(job_id: str, registry_dir: str) -> str:
return os.path.join(registry_dir, "{}.heartbeat.pid".format(job_id))
def _pid_alive(pid: int) -> bool:
try:
os.kill(pid, 0)
except ProcessLookupError:
return False
except PermissionError:
return True
try:
state = subprocess.run(["ps", "-o", "stat=", "-p", str(pid)],
capture_output=True, text=True).stdout.strip()
except OSError:
return True
return bool(state) and not state.startswith("Z")
def running_timer(job_id: str, registry_dir: str) -> Optional[int]:
"""PID of a live timer for this job, or None."""
try:
with open(pidfile_path(job_id, registry_dir)) as fh:
pid = int(fh.read().strip() or 0)
except (OSError, ValueError):
return None
if pid > 0 and _pid_alive(pid):
return pid
return None
def _is_timer_process(pid: int, job_id: str) -> bool:
"""The pid really is this job's timer (a stale pidfile after a crash may
name a recycled pid that now belongs to something else)."""
entry = _process_table().get(pid)
if entry is None:
return False
command = entry[1]
return "lib_py.delegation.heartbeat" in command and job_id in command
DRAIN_ENV = "MAM_HEARTBEAT_DRAIN_S"
# Short on purpose: the barrier already keeps any beat from taking a seq after
# the terminal, so the drain only lets an idle timer exit cleanly. A beat still
# on the wire is cancelled with the timer (its seq is older than the terminal's)
# rather than holding back the terminal event - which may be the orchestrator
# closing the job - for seconds of broker round trips.
DEFAULT_DRAIN_S = 1.0
def drain_seconds() -> float:
"""How long a terminal publish waits for the timer to drain (env override)."""
try:
return max(0.0, float(os.environ.get(DRAIN_ENV, DEFAULT_DRAIN_S)))
except ValueError:
return DEFAULT_DRAIN_S
def stop_timer(job_id: str, registry_dir: str, drain: Optional[float] = None) -> bool:
"""Terminate the job's timer if one runs. Returns True when one was signalled.
``drain`` (seconds): also wait for the timer to exit - on TERM it stops
scheduling and joins its in-flight beats - and SIGKILL it if it has not
gone by then, so none of its beats can still publish afterwards. A terminal
publish uses this (review round 2, codex R3): "TERM sent" is not "timer
stopped"."""
pid = running_timer(job_id, registry_dir)
path = pidfile_path(job_id, registry_dir)
if pid is None or not _is_timer_process(pid, job_id):
try:
os.unlink(path)
except OSError:
pass
return False
try:
os.kill(pid, signal.SIGTERM)
except OSError:
pass
if drain is not None:
deadline = time.monotonic() + drain
while time.monotonic() < deadline and _pid_alive(pid):
time.sleep(0.1)
if _pid_alive(pid):
logger.warning("heartbeat timer %d for %s did not drain within %.0fs; killing it", pid, job_id, drain)
try:
os.kill(pid, signal.SIGKILL)
except OSError:
pass
deadline = time.monotonic() + 2.0
while time.monotonic() < deadline and _pid_alive(pid):
time.sleep(0.05)
try:
os.unlink(path)
except OSError:
pass
return True
def barrier_path(job_id: str, registry_dir: str) -> str:
return os.path.join(registry_dir, "{}.heartbeat.barrier".format(job_id))
def raise_barrier(job_id: str, registry_dir: str, dispatch_token=None, attempt_id=None) -> None:
"""Mark this attempt as ending (review round 2, codex R3).
Written under the registry lock - the lock `next_seq` takes - so a beat
either took its seq before this point (and the terminal publisher then
waits for the timer to drain) or meets the barrier when it asks for a seq
and is refused without consuming one."""
with mqtt_common.registry_lock(registry_dir):
with open(barrier_path(job_id, registry_dir), "w") as fh:
json.dump({"dispatch_token": dispatch_token, "attempt_id": attempt_id}, fh)
def barrier_blocks(job_id: str, registry_dir: str, dispatch_token=None, attempt_id=None) -> bool:
"""True when a terminal barrier was raised for this attempt (a later
attempt, with its own token, is not blocked). Check it under the registry
lock when the answer must be atomic with a seq."""
try:
with open(barrier_path(job_id, registry_dir)) as fh:
barrier = json.load(fh)
except (OSError, ValueError):
return False
if not isinstance(barrier, dict):
return True
if dispatch_token and barrier.get("dispatch_token"):
return barrier["dispatch_token"] == dispatch_token
if attempt_id is not None and barrier.get("attempt_id") is not None:
return int(barrier["attempt_id"]) == int(attempt_id)
return True
def start_timer(job_id: str, registry_dir: str, interval: int,
dispatch_token: Optional[str] = None, attempt_id: Optional[int] = None,
python: Optional[str] = None, watch_pid: Optional[int] = None) -> int:
"""Spawn the detached timer process and return its pid.
A timer that already runs for the job is stopped first: a second `started`
for the same job (a retry of the same command) must not double the rate.
``watch_pid`` binds the timer to a process (default: the nearest agent-CLI
ancestor of this process, if any); 0 disables the watch explicitly.
"""
stop_timer(job_id, registry_dir)
if watch_pid is None:
watch_pid = nearest_agent_cli_ancestor()
cmd: List[str] = [python or sys.executable, "-m", "lib_py.delegation.heartbeat",
"--job", job_id, "--registry-dir", registry_dir,
"--interval", str(int(interval))]
if dispatch_token:
cmd += ["--expect-dispatch-token", dispatch_token]
if attempt_id is not None:
cmd += ["--attempt-id", str(int(attempt_id))]
if watch_pid:
cmd += ["--watch-pid", str(int(watch_pid))]
env = dict(os.environ)
# The timer imports lib_py from the same tree as this process.
pkg_root = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
env["PYTHONPATH"] = pkg_root + (os.pathsep + env["PYTHONPATH"] if env.get("PYTHONPATH") else "")
log_path = os.path.join(registry_dir, "{}.heartbeat.log".format(job_id))
with open(log_path, "ab") as log:
proc = subprocess.Popen(cmd, stdin=subprocess.DEVNULL, stdout=log, stderr=subprocess.STDOUT,
start_new_session=True, env=env, cwd=os.getcwd())
with open(pidfile_path(job_id, registry_dir), "w") as fh:
fh.write(str(proc.pid))
logger.info("heartbeat timer pid %d for job %s every %ss (watching pid %s)",
proc.pid, job_id, interval, watch_pid or "none")
return proc.pid
def _should_stop(job_id: str, registry_dir: str, dispatch_token, attempt_id,
watch_pid: Optional[int] = None) -> Optional[str]:
if watch_pid and not _pid_alive(watch_pid):
return "watched agent process {} is gone".format(watch_pid)
try:
rec = load_job(job_id, registry_dir)
except FileNotFoundError:
return "job record gone"
if rec.get("status") in TERMINAL_STATUSES:
return "job is {}".format(rec.get("status"))
if barrier_blocks(job_id, registry_dir, dispatch_token, attempt_id):
return "the terminal barrier for this attempt is raised"
if dispatch_token and rec.get("dispatch_token") != dispatch_token:
return "dispatch token changed (re-dispatched)"
if attempt_id is not None and rec.get("attempt_id", rec.get("iteration", 1)) != attempt_id:
return "attempt changed (re-dispatched)"
return None
def run(job_id: str, registry_dir: str, interval: int, dispatch_token=None,
attempt_id=None, max_lifetime: Optional[float] = None,
watch_pid: Optional[int] = None) -> int:
"""The timer loop. Runs until a stop condition holds."""
from lib_py.delegation import publish_event # late import: the CLI imports us
interval = max(1, int(interval))
if max_lifetime is None:
try:
max_lifetime = float(load_job(job_id, registry_dir).get("timeout_sec", 3600)) + interval
except FileNotFoundError:
return 1
stop = {"flag": False}
def _on_term(_signum, _frame):
stop["flag"] = True
signal.signal(signal.SIGTERM, _on_term)
signal.signal(signal.SIGINT, _on_term)
started = time.monotonic()
own_pidfile = pidfile_path(job_id, registry_dir)
# Fixed cadence: the next beat is due `interval` after the previous one
# was *due*, not after its publish returned, so a slow broker (seconds per
# ACK) does not stretch the period the contract promises. Each beat is
# recorded on disk before its wire publish, so the on-disk cadence holds
# even when the wire lags. Sleep first: `started` was just published.
next_due = time.monotonic() + interval
in_flight: List[threading.Thread] = []
while not stop["flag"]:
while time.monotonic() < next_due and not stop["flag"]:
time.sleep(min(0.5, max(0.0, next_due - time.monotonic())))
if stop["flag"]:
break
next_due += interval
if next_due < time.monotonic():
next_due = time.monotonic() + interval # fell far behind: resync
reason = _should_stop(job_id, registry_dir, dispatch_token, attempt_id, watch_pid)
if reason:
logger.info("heartbeat timer for %s stopping: %s", job_id, reason)
break
if time.monotonic() - started > max_lifetime:
logger.info("heartbeat timer for %s stopping: lifetime %.0fs exceeded", job_id, max_lifetime)
break
argv = ["--registry-dir", registry_dir, "--job", job_id, "--event", "progress",
"--detail", HEARTBEAT_DETAIL, "--attempts", "2"]
if dispatch_token:
argv += ["--expect-dispatch-token", dispatch_token]
if attempt_id is not None:
argv += ["--attempt-id", str(attempt_id)]
# Each beat publishes in its own thread: the local record (seq, HMAC,
# events.log) is taken at once, and the wire publish - seconds per ACK
# on a slow broker - must not delay the next beat. In-flight beats are
# capped so a dead broker cannot pile up threads without bound.
in_flight[:] = [t for t in in_flight if t.is_alive()]
if len(in_flight) >= MAX_IN_FLIGHT:
logger.warning("heartbeat for %s skipped: %d publishes still in flight", job_id, len(in_flight))
continue
def _beat(argv=argv):
try:
# _beat=True: admitted under the seq lock, never after this
# attempt's terminal barrier (review round 2, codex R3)
rc = publish_event.main(argv, _beat=True)
except Exception as exc: # pragma: no cover - defensive
logger.warning("heartbeat publish raised: %s", exc)
rc = 2
if rc == 4:
logger.info("heartbeat publish refused (terminal barrier, terminal record or stale attempt); "
"timer for %s will stop", job_id)
stop["flag"] = True
t = threading.Thread(target=_beat, daemon=True)
t.start()
in_flight.append(t)
for t in in_flight:
t.join(timeout=15)
try:
with open(own_pidfile) as fh:
if fh.read().strip() == str(os.getpid()):
os.unlink(own_pidfile)
except (OSError, ValueError):
pass
return 0
def main(argv=None) -> int:
parser = argparse.ArgumentParser(description="automatic heartbeat timer for a delegated job")
parser.add_argument("--job", required=True)
parser.add_argument("--registry-dir", default=default_registry_dir())
parser.add_argument("--interval", type=int, required=True, help="heartbeat period N in seconds")
parser.add_argument("--expect-dispatch-token", default=None)
parser.add_argument("--attempt-id", type=int, default=None)
parser.add_argument("--max-lifetime", type=float, default=None)
parser.add_argument("--watch-pid", type=int, default=None,
help="stop once this process (the agent) is gone")
parser.add_argument("-v", "--verbose", action="store_true")
args = parser.parse_args(argv)
mqtt_common.ensure_env_loaded()
mqtt_common.setup_logging(logging.DEBUG if args.verbose else logging.INFO)
return run(args.job, args.registry_dir, args.interval, args.expect_dispatch_token,
args.attempt_id, args.max_lifetime, args.watch_pid)
if __name__ == "__main__":
sys.exit(main())