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Posts tagged “Monitoring”

Deploy markers name the guilty release: p95 per endpoint before and after a deploy, with /v1/search flagged as a regression
Monitoring

Deploy markers: tying a latency regression to the release that caused it

p95 doubled, and there were three deploys and a flag flip since yesterday. Deploy markers and a version field on every log line turn "which release did this" into a five-minute query. Here is how to set both up for a Node API.

Jason Fill October 13, 2026 6 min read
Third-party API latency, measured. Cover graphic for a guide to measuring per-vendor latency, errors and throttling from Node.
Monitoring

Third-party API latency: measuring vendor slowness and failures in Node

The vendor status page is green and your checkout is slow. Here is how to measure third-party API latency and failures from your own Node servers, per dependency, without wrapping fetch.

Jason Fill September 17, 2026 6 min read
API alerting best practices for small teams. Cover graphic for a guide to choosing which API symptoms to page on for a Node API.
Monitoring

API alerting best practices: what to page on for a Node API

A 3am CPU page that meant nothing, then a real outage that paged nobody. Here is the short list of alerts a small Node API team needs, with rules and code to match.

Jason Fill August 4, 2026 5 min read
Node.js event loop lag, explained. Cover graphic for a guide to measuring Node.js event loop delay and finding the code that blocks it.
Monitoring

Node.js event loop lag: the metric that explains "random" slowness

Every endpoint slow at once, database fine, CPU looks idle: that is event loop lag. Here is how to measure it in Node with built-in tools and find the code that blocks.

Jason Fill June 22, 2026 6 min read
Node.js memory leak? Take three snapshots. Cover graphic for a guide to finding Node.js memory leaks with heap snapshots in Chrome DevTools.
Monitoring

Node.js memory leak debugging with heap snapshots

The container keeps getting OOM-killed and restarts hide why. Here is the three-snapshot method that finds a Node.js memory leak, and how to do it safely in production.

Jason Fill May 25, 2026 6 min read
Your error budget in two lines. Cover graphic for a guide to setting SLOs and an error budget for a small Node API team.
Monitoring

SLOs and an error budget for a small API team, without the enterprise ceremony

Is a 0.4% error rate bad? Without a target, nobody knows. Set one availability and one latency SLO for your Node API, compute the error budget from your request logs, and agree what happens when it runs out.

Jason Fill March 9, 2026 6 min read
Node.js health checks that tell the truth. Cover graphic for a guide to liveness and readiness health checks in Node.js.
Monitoring

Node.js health checks that tell the truth: liveness vs readiness

A database blip should not restart every replica of your API. Split /health into liveness and readiness, with Express and Fastify code you can ship today.

Jason Fill January 13, 2026 6 min read
API latency percentiles, read honestly. Cover graphic for a guide to reading p50, p95 and p99 API latency correctly.
Monitoring

API latency percentiles: how to read p50, p95 and p99 without fooling yourself

Your average latency says 102 ms; a customer says the app hangs for two seconds. Both are true. Learn to read p50, p95 and p99, avoid the four classic mistakes, and record percentiles per route in Node.

Jason Fill December 18, 2025 7 min read