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Node.js40 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.
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EXPLAIN plans, heap snapshots and flame graphs
Every post starts from a real symptom: a p95 that doubled, a pod that grew 40 MB an hour, a migration that locked a table. Then we show the commands, the output and the diff.
Latest posts
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.
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.