perf: Access to performance monitoring and observability operations is limited
The kernel's perf_event_paranoid setting stops unprivileged users profiling, and most distributions ship it at 2, while Debian and Ubuntu kernels carry a patch for stricter levels that block it entirely. In a container the setting comes from the host kernel and the seccomp profile also blocks perf_event_open, so changing it inside the container does nothing.
Quick fix
Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.
# Current setting (higher is stricter)
cat /proc/sys/kernel/perf_event_paranoid
# Allow user space profiling of your own processes until reboot
sudo sysctl kernel.perf_event_paranoid=1
# Kernel symbols too
sudo sysctl kernel.kptr_restrict=0
# Persist it
echo 'kernel.perf_event_paranoid = 1' | sudo tee /etc/sysctl.d/90-perf.conf
# Or run the profile as root without changing the setting
sudo perf record -g -p "$(pgrep -n myapp)" -- sleep 30
# Containers: set it on the host, and allow perf_event_open in seccompHow to diagnose Performance errors
Performance failures rarely produce an error message. They produce timeouts elsewhere. The three classic causes are stop-the-world garbage collection, thread pool starvation (all workers blocked on I/O so new requests queue), and event loop blocking in single-threaded runtimes. All three look identical from outside: latency climbs, then upstream timeouts fire. Distinguishing them requires looking inside the process.
If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.
- Measure the p99, not the mean. Averages hide exactly the pauses that cause timeouts.
- For the JVM, enable GC logging (
-Xlog:gc*) and correlate pause durations with latency spikes before tuning anything. - For thread pools, log active versus queued task counts. A queue that grows while CPU is idle is starvation, and the fix is asynchronous I/O, not more threads.
- In Node.js, measure event loop lag directly (
perf_hooks.monitorEventLoopDelay). Any synchronous work over a few milliseconds per request will show up here. - Profile before optimising.
pprof,async-profiler,py-spyand Chrome's profiler all point at the real hot path, which is rarely where intuition suggests.
Tools worth reaching for
async-profilergo tool pprofpy-spyperf_hooks.monitorEventLoopDelay-Xlog:gc*
Authoritative references
Primary documentation for this error, worth reading before applying any fix in production.
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Something missing or wrong?
This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.