Merge pull request #13481 from banjoh/em/add-cpu-memory-profiling-flags

feat: Enable CPU and memory profiling

CONTRIBUTING.md

@@ -276,12 +276,26 @@ Like any good open source project, we use Pull Requests (PRs) to track code chan
       or explicitly request another OWNER do that for them.
     - If the owner of a PR is _not_ listed in `OWNERS`, any core maintainer may merge the PR.
 
-#### Documentation PRs
+### Documentation PRs
 
 Documentation PRs should be made on the docs repo: <https://github.com/helm/helm-www>. Keeping Helm's documentation up to date is highly desirable, and is recommended for all user facing changes. Accurate and helpful documentation is critical for effectively communicating Helm's behavior to a wide audience.
 
 Small, ad-hoc changes/PRs to Helm which introduce user facing changes, which would benefit from documentation changes, should apply the `docs needed` label. Larger changes associated with a HIP should track docs via that HIP. The `docs needed` label doesn't block PRs, and maintainers/PR reviewers should apply discretion judging in whether the `docs needed` label should be applied.
 
+### Profiling PRs
+
+If your contribution requires profiling to check memory and/or CPU usage, you can set `HELM_PPROF_CPU_PROFILE=/path/to/cpu.prof` and/or `HELM_PPROF_MEM_PROFILE=/path/to/mem.prof` environment variables to collect runtime profiling data for analysis. You can use Golang's [pprof](https://github.com/google/pprof/blob/main/doc/README.md) tool to inspect the results.
+
+Example analysing collected profiling data
+```
+HELM_PPROF_CPU_PROFILE=cpu.prof HELM_PPROF_MEM_PROFILE=mem.prof helm show all bitnami/nginx
+
+# Visualize graphs. You need to have installed graphviz package in your system
+go tool pprof -http=":8000" cpu.prof
+
+go tool pprof -http=":8001" mem.prof
+```
+
 ## The Triager
 
 Each week, one of the core maintainers will serve as the designated "triager" starting after the

cmd/helm/profiling.go

@@ -0,0 +1,91 @@
+/*
+Copyright The Helm Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"runtime"
+	"runtime/pprof"
+)
+
+var (
+	cpuProfileFile *os.File
+	cpuProfilePath string
+	memProfilePath string
+)
+
+func init() {
+	cpuProfilePath = os.Getenv("HELM_PPROF_CPU_PROFILE")
+	memProfilePath = os.Getenv("HELM_PPROF_MEM_PROFILE")
+}
+
+// startProfiling starts profiling CPU usage if HELM_PPROF_CPU_PROFILE is set
+// to a file path. It returns an error if the file could not be created or
+// CPU profiling could not be started.
+func startProfiling() error {
+	if cpuProfilePath != "" {
+		var err error
+		cpuProfileFile, err = os.Create(cpuProfilePath)
+		if err != nil {
+			return fmt.Errorf("could not create CPU profile: %w", err)
+		}
+		if err := pprof.StartCPUProfile(cpuProfileFile); err != nil {
+			cpuProfileFile.Close()
+			cpuProfileFile = nil
+			return fmt.Errorf("could not start CPU profile: %w", err)
+		}
+	}
+	return nil
+}
+
+// stopProfiling stops profiling CPU and memory usage.
+// It writes memory profile to the file path specified in HELM_PPROF_MEM_PROFILE
+// environment variable.
+func stopProfiling() error {
+	errs := []error{}
+
+	// Stop CPU profiling if it was started
+	if cpuProfileFile != nil {
+		pprof.StopCPUProfile()
+		err := cpuProfileFile.Close()
+		if err != nil {
+			errs = append(errs, err)
+		}
+		cpuProfileFile = nil
+	}
+
+	if memProfilePath != "" {
+		f, err := os.Create(memProfilePath)
+		if err != nil {
+			errs = append(errs, err)
+		}
+		defer f.Close()
+
+		runtime.GC() // get up-to-date statistics
+		if err := pprof.WriteHeapProfile(f); err != nil {
+			errs = append(errs, err)
+		}
+	}
+
+	if err := errors.Join(errs...); err != nil {
+		return fmt.Errorf("error(s) while stopping profiling: %w", err)
+	}
+
+	return nil
+}

cmd/helm/root.go

@@ -95,6 +95,16 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 		Short:        "The Helm package manager for Kubernetes.",
 		Long:         globalUsage,
 		SilenceUsage: true,
+		PersistentPreRun: func(_ *cobra.Command, _ []string) {
+			if err := startProfiling(); err != nil {
+				log.Printf("Warning: Failed to start profiling: %v", err)
+			}
+		},
+		PersistentPostRun: func(_ *cobra.Command, _ []string) {
+			if err := stopProfiling(); err != nil {
+				log.Printf("Warning: Failed to stop profiling: %v", err)
+			}
+		},
 	}
 	flags := cmd.PersistentFlags()