PROFILING.md

Profiling Knative Serving

Knative Serving allows for collecting runtime profiling data expected by the pprof visualization tool. Profiling data is available for the autoscaler, activator, controller, webhook and for the queue-proxy container which is injected into the user application pod. When enabled Knative serves profiling data on the default port 8008 through a web server.

Steps to get profiling data

Edit the config-observability ConfigMap and add profiling.enable = "true":

kubectl edit configmap config-observability -n knative-serving

Use port-forwarding to get access to Knative Serving pods. For example, activator:

ACTIVATOR_POD=$(kubectl -n knative-serving get pods -l app=activator -o custom-columns=:metadata.name --no-headers)
kubectl port-forward -n knative-serving $ACTIVATOR_POD 8008:8008

View all available profiles at http://localhost:8008/debug/pprof/ through a web browser or request specific profiling data using one of the commands below:

Heap profile

go tool pprof http://localhost:8008/debug/pprof/heap

30-second CPU profile

go tool pprof http://localhost:8008/debug/pprof/profile?seconds=30

Go routine blocking profile

go tool pprof http://localhost:8008/debug/pprof/block

5-second execution trace

wget http://localhost:8008/debug/pprof/trace\?seconds\=5 && go tool trace trace\?seconds\=5

All memory allocations

go tool pprof http://localhost:8008/debug/pprof/allocs

Holders of contended mutexes

go tool pprof http://localhost:8008/debug/pprof/mutex

Stack traces of all current goroutines

go tool pprof http://localhost:8008/debug/pprof/goroutine

Stack traces that led to the creation of new OS threads

go tool pprof http://localhost:8008/debug/pprof/threadcreate

Command line arguments for the current program

curl http://localhost:8008/debug/pprof/cmdline --output -

More information on profiling Go applications in this blog