// Example: Simple Leader Election
const nodes = [NODE_1, NODE_2, NODE_3];
const consensus = new Raft();
async function reachConsensus() {
const leader = await consensus.selectLeader(nodes);
console.log(`Leader elected: ${leader.id}`);
return consensus.finalize();
}
reachConsensus();
Why Consensus Matters
In distributed systems, achieving agreement across independent nodes is like herding cats. Consensus algorithms ensure all participants agree on a single data value. Imagine blockchain, databases, or cloud services failing simultaneously without this core mechanism.
"Consensus is the heartbeat of fault-tolerant systems." – Distributed Systems Handbook
Key Requirements
- • Termination
- • Validity
- • Agreement
- • Integrity
Real-World Applications
- • Blockchain networks
- • Distributed databases
- • Kubernetes
- • Cloud orchestration
Algorithm Showdown
{/* Algorithm Cards */}Paxos
Google's foundational algorithm for large-scale systems. While powerful, it's complex to implement and requires careful tuning of phases.
Raft
Simpler than Paxos with clear leader election and log replication. Popular in etcd and Kubernetes for its intuitive design.
PBFT
Provides robust Byzantine fault tolerance but with higher computational overhead. Common in cryptocurrency protocols like Ethereum.
| Metric | Paxos | Raft | PBFT |
|---|---|---|---|
| Nodes | 5+ | 3+ | 3N |
| Throughput | ~1k ops/sec | ~2.5k ops/sec | ~100 ops/sec |
| Fault Tolerance | F | Crash | BFT |
Choosing the Right Algorithm
When designing your next distributed system, consider these criteria:
- • Network Stability: Paxos requires stable communication paths
- • Node Count: Raft scales better than PBFT •Consistency Model: Linearizability vs. Eventual Consistency
- • Trust Level: PBFT requires all nodes to be trusted
// Simplified Raft Leader Election
class RaftNode {
constructor(id) {
this.id = id;
this.state = 'follower';
this.heartbeat = 500;
}
becomeCandidate() {
this.state = 'candidate';
this.votesForSelf = 0;
}
async requestVote(node) {
return new Promise(resolve => {
setTimeout(() => {
this.votesForSelf++;
resolve(this.votesForSelf > this.quorum);
}, Math.random() * 1000);
});
}
}
