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What Is a Heartbeat?

A heartbeat is a small message emitted at a regular interval to indicate that a node or process is still running. Peers or a coordinator track these signals and treat a missed sequence, beyond a timeout, as evidence the sender has failed. Heartbeats drive failure detection, lease renewal, and membership decisions.

Why it matters

Distributed systems cannot tell a crashed node from a slow one without a signal. Heartbeats provide that signal, but the timeout must be tuned to avoid declaring a merely slow node dead.

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