Node.js
40 MB an hour: the Node memory leak hiding behind setMaxListeners(0)
A postmortem of a slow leak in a Node ingest service: how two heap snapshots, one retainer chain and a silenced warning led us to the bug.
A group engineering blog
Careful notes on the systems we run
Four developers writing about Postgres, Node, Go and the tooling around them. One post every two weeks or so, each one with code you can run and a fix we actually shipped.
- 9 stories
- 4 writers
- RSS
Start here
Reliability
Idempotency keys for webhooks: the ten lines that stop double charges
Webhook providers deliver at least once, so your handler will see duplicates. A unique key and one transaction in Postgres make that harmless.
Tooling
A boring monorepo layout that has survived three years and 40 packages
Three top-level folders, one dependency rule and pnpm filters for CI. The monorepo structure we keep coming back to, and what we stopped doing.
Latest posts
How to read a flame graph without guessing
Width is time, height is call depth, colour means nothing. A practical guide to reading CPU flame graphs from Go's pprof, using a real regression we fixed.
Renaming a column without downtime: expand, migrate, contract
ALTER TABLE ... RENAME COLUMN takes a millisecond and breaks every running pod. A step-by-step expand and contract rename in Postgres, with the trigger we use.
TIL: our trial countdown was wrong one day a year, and only in Europe
A date test that passed for months failed on a CI runner in Berlin. What we learned about DST, local midnight and testing code that reads the clock.
Feature flags without a vendor: one table, one function, one rule
For most teams, feature flags are a Postgres table, a hashing function and a policy about expiry dates. Here is ours, and when we would pay for a product instead.
The index that did nothing: reading an EXPLAIN plan line by line
We added an index to fix a 1.2 second query and the plan did not change. Here is how EXPLAIN ANALYZE told us why, and the partial index that worked.
A retry helper with full jitter, in about 40 lines of Go
Exponential backoff without jitter turns one outage into synchronized waves of retries. Here is a small Go helper that gets backoff, jitter and cancellation right.