Comparison / Monitoring models
Heartbeat vs Dead Man vs Dead Hand Monitoring
Three related questions, three different failure classes: check-in, missing check-in and stale progress.
Concept comparison; implementation status is explicit per productStart with the state you need to distinguish
| Observed state | Heartbeat Monitor | Dead Man Monitor | Dead Hand Monitor |
|---|---|---|---|
| Process checks in | Records evidence | Uses the evidence | Uses the evidence |
| Check-ins stop | Shows the last evidence | Evaluates the missing condition | Cannot evaluate progress without a fresh check-in |
| Check-ins continue but work stops | Usually misses it | Usually sees the process as alive | Evaluates stale progress when a valid marker exists |
The practical distinction
Heartbeat is evidence. Dead Man is a silence policy. Dead Hand is a progress-freshness policy. Combining the names into one generic monitoring feature hides the operational question and creates false confidence.
Implementation boundary
Current HPH provides the authenticated heartbeat and signal foundation. Dead Man state calculation and Dead Hand progress evaluation are product-layer work that must be implemented before they can be advertised as live customer features.
How to choose
- Need recent check-in evidence? Start with Heartbeat Monitor.
- Need to investigate expected silence? Use the Dead Man model.
- Need to detect a live but frozen worker? Design a meaningful progress marker and evaluate the Dead Hand model.