Code RoomCold pod connection storms
MediumPrep Room Coding #2854

Cold pod connection storms

On-callReliability & on-callMid–Senior~25 min

After each rolling deploy, freshly started pods show a 20-30 second window of elevated p99 and a burst of `connection reset` / handshake-timeout errors to your database and a downstream gRPC service, then settle. It's not GC or JIT — profiling shows the time going into establishing new TCP+TLS connections and the DB driver doing per-connection auth. The connection pools are configured lazy (`min-idle = 0`), so a fresh pod opens connections only as the first requests arrive — right when the LB hits it at full traffic. How do you triage and fix this cold-start?

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

0:00 of about 25 min
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