How to detect node failure in a distributed system?

How to detect node failure in a distributed system?

The following figure shows the 6 major heartbeat detection mechanisms.

In a distributed system, the heartbeat mechanism is crucial for monitoring the health and status of various components. Several common heartbeat detection mechanisms play a key role in real-time monitoring systems to ensure high availability and stability of the system.

1. Push-based heartbeat

The most basic form of heartbeat involves sending periodic signals from one node to another node or to a monitoring service.

If the heartbeat signal stops arriving within the specified time interval, the system will consider the node to have failed.

This method is simple to implement, but network congestion may lead to false positives.

2. Pull-based heartbeat

The central monitor can periodically "pull" status information from nodes instead of nodes actively sending heartbeats.

This can reduce network traffic, but may increase failure detection latency.

3.Heartbeat with health check

Heartbeat signals can provide important data about CPU usage, memory usage, or specific application metrics by including diagnostic information about the health of the node.

This approach provides more detailed information about the node, allowing more granular decisions to be made. However, it adds complexity and potentially greater network overhead.

4.Heartbeat with timestamp

Heartbeats containing timestamps can not only help the receiving node or service determine whether the node is alive, but also determine whether there is network delay that affects communication.

5. Heartbeat with confirmation

In this mode, the recipient of the heartbeat message must send back an acknowledgment. This not only ensures that the sender is alive, but also that the network path between the sender and receiver is normal.

6.Heartbeat with quorum

In some distributed systems, especially those involving consensus protocols such as Paxos or Raft, the concept of quorum (majority of nodes) is used.

Heartbeats can be used to establish or maintain a quorum, ensuring a sufficient number of nodes are running for the system to make decisions. This introduces the complexity of implementing and managing quorum changes as nodes join or leave the system.

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