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Code RoomSpring Boot OOM from non-heap memory growth
MediumPrep Room Coding #2551

Spring Boot OOM from non-heap memory growth

On-callAlgorithms & data structuresMid–Senior~30 min

A Spring Boot payments service running on Kubernetes started CrashLooping at 02:00. Dashboards show pods restarting every ~4 minutes with exit code 137; container memory climbs steadily from 600MB to the 1Gi limit then drops to zero on restart. JVM heap-used (from Micrometer) only reaches ~480MB before each kill, well under the -Xmx of 768m. GC pause time and old-gen occupancy look normal. There was no deploy; traffic is flat versus last week. The only recent change was an infra ticket that lowered the pod memory limit from 1.5Gi to 1Gi the previous afternoon. Walk through how you triage and mitigate this.

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 30 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.