A fan-out of N in-process subagents used to add one sleeping daemon
thread per delegated child (delegate heartbeat, 30s) and one or two per
active turn (durable turn-lease refresher; turn-liveness watchdog). A
profiled session with ~130 children was carrying ~1000 threads. All
of these timers now run on a single process-wide daemon thread.
- agent/periodic_scheduler.py (new): heap-ordered periodic scheduler on
one Condition-driven daemon thread. schedule(fn, interval) -> handle;
handle.cancel(wait=) blocks for an in-flight run like the old join.
A callback returning False stops itself; a raising callback is logged
at debug and rescheduled, so one bad timer cannot kill the rest.
- tools/delegate_tool.py: _heartbeat_loop body -> _heartbeat_tick,
scheduled at _HEARTBEAT_INTERVAL; stale-cycle closure state and
idle/in-tool thresholds unchanged; cancel(wait=5) in finally where the
stop-event + join(5) lived.
- run_agent.py: _refresh_durable_turn_lease body scheduled at
_lease_refresh_interval; lease-lost / refresh-error interrupt paths
and the stop-event fencing are unchanged; the join(timeout=1.0) is now
cancel(wait=1.0) so the interrupt clear still runs after any in-flight
tick.
- agent/turn_liveness.py: TurnLivenessWatchdog.make_thread/start ->
schedule(); the poll body is _tick(), same sampling state machine.
Bench (evals/fanout_resource_bench.py, 30 children / 10 worktrees,
ok=30/30 both): peak threads 168 -> 132. At peak the old tree held 30
"Thread-N (_heartbeat_loop)" threads; the new one holds zero plus one
"hermes-periodic-scheduler".
Teknium
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