SLO 消耗率监控

🌐 SLO burn rate monitoring

const { createHistogram } = require('node:perf_hooks');

// Track latency with EWMA (half-life 100 samples) and a 200ms SLO threshold
const latency = createHistogram({
  halfLife: 100,
  threshold: 200_000_000,  // 200ms in nanoseconds
});

// Record request latencies...

// Smoothed error rate: probability of exceeding the threshold
console.log(`Error rate: ${(latency.ewmaErrorRate * 100).toFixed(2)}%`);

// Burn rate against a 99.9% SLO
// >1 means the error budget is depleting faster than allowed
const rate = latency.burnRate(0.999);
console.log(`Burn rate: ${rate.toFixed(2)}x`);

// EWMA mean and stddev track the smoothed latency
console.log(`EWMA latency: ${latency.ewmaMean.toFixed(0)}ns`);
console.log(`EWMA stddev:  ${latency.ewmaStddev.toFixed(0)}ns`); 拷贝