PID limit exhaustion from zombie processes
A CI build host starts failing new builds with 'fork: retry: Resource temporarily unavailable' and SSH logins are refused, though CPU, memory, and disk all look fine. The host runs many short-lived containerized build steps. `ps -eLf | wc -l` shows ~30,000 tasks; `cat /proc/sys/kernel/pid_max` is 32768. A build job introduced last week spawns a per-test helper process but, on a code path hit by a flaky test, never reaps the children — `ps` shows thousands of <defunct> (zombie) processes parented to that job. Triage and fix.
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 40 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.