Infrastructure · Primitives
Heartbeat
Liveness detection via periodic signals
Definition
Mechanism
Periodic Liveness Signal: An entity emits Signal (Heartbeat) every interval I. Missing K consecutive heartbeats triggers failure detection. Heartbeat may include health metrics. Receiver tracks last-seen timestamp. It feeds into the Quorum detector, allowing the collective to identify and prune dead nodes.
Preconditions
- Active component
- Monitor
Postconditions
- Liveness confirmed
Invariants
- Missing `timeout_multiplier` consecutive intervals triggers failure DETECTION, which is a suspicion and not a fact about the emitter.
- Emission interval stays within `interval`.
Risks
Failure modes
False failure detection
the node is alive and its heartbeat was delayed, so absence of signal was read as absence of the emitter.
Heartbeat outlives usefulness
the emitter is alive and the work it was doing is not, so liveness is reported while progress has stopped.
Relationships
Builds on
Accepts
Raw information emission
Composes with
Minimum participation threshold
References
Continuous observation of state over time
Used by
Composes with
Society
Work handoff: delegate → accept/refuse → heartbeat → result-or-failure
References
Real-time readable intent broadcasting
Society
Fluid, organic synchronization without rigid clock ticks.
Society
Continuous ownership of a system invariant
Formal state machine governing task progression
Reference
Parameters
intervalDuration, [100ms, 60s]- Time between heartbeats
timeout_multiplierInteger, [2, 5]- Missed beats before failure