nice and renice for noisy neighbors

[snippet] 2026-09-25

nice and renice for noisy neighbors

nice is CPU scheduling priority (−20 urgent … 19 meek). It does not cap memory or I/O by itself.

# Start a batch job that shouldn’t steal CPU from the API
nice -n 19 python /opt/jobs/reindex.py

# Already running? bump it down
renice -n 10 -p $(pgrep -n reindex.py)

# Check: NI column in top / ps
ps -o pid,ni,comm -p $(pgrep -n reindex.py)

Scenario: Nightly compaction fights daytime traffic. Wrap it in nice -n 19 so interactive workers win CPU contention. For disk-heavy jobs pair with ionice; nice alone won’t stop an I/O storm.