What Is Leader Election?
Leader election in distributed systems is the process of selecting a single node as the leader (coordinator) to manage tasks and ensure consistency across all nodes.
When to Use
Leader election is used in distributed databases, consensus protocols, and cluster management whenever a single point of coordination is required for tasks like write ordering or conflict resolution.
Example
Think of a database cluster: one node is elected leader to handle writes. If it crashes, a new leader is quickly chosen so the system stays available.
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Why Is It Important
Consistency and fault tolerance depend on leader election. Without it, nodes might act independently, leading to conflicts or downtime.
Interview Tips
In interviews, define leader election clearly, give a simple example, and mention algorithms like Bully or Raft. Highlight how systems recover when a leader fails.
A leader simplifies decision-making but introduces a single point of coordination. Elections add latency, and the leader can become a bottleneck.
Pitfalls
Common mistakes include ignoring network partitions (causing split-brain), slow re-election times, or hardcoding leaders instead of using robust algorithms.
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