[receiver/hostmetrics] Cheaper parent PID and number of threads retrieval on Windows

.chloggen/hostmetricsreceiver-process-scraper-windows-optimization.yaml

@@ -0,0 +1,29 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'enhancement'
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: hostmetricsreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: >
+  Reduced the cost of retrieving number of threads and parent process ID on Windows.
+  Disable the featuregate `hostmetrics.process.onWindowsUseNewGetProcesses` to fallback to the previous implementation.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32947, 38589]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/hostmetricsreceiver/internal/scraper/processscraper/get_process_handles_others.go

@@ -0,0 +1,27 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+//go:build !windows
+
+package processscraper // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/processscraper"
+
+import (
+	"context"
+
+	"github.com/shirou/gopsutil/v4/process"
+)
+
+func getGopsutilProcessHandles(ctx context.Context) (processHandles, error) {
+	processes, err := process.ProcessesWithContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+	wrapped := make([]wrappedProcessHandle, len(processes))
+	for i, p := range processes {
+		wrapped[i] = wrappedProcessHandle{
+			Process: p,
+		}
+	}
+
+	return &gopsProcessHandles{handles: wrapped}, nil
+}

receiver/hostmetricsreceiver/internal/scraper/processscraper/get_process_handles_windows.go

@@ -0,0 +1,84 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+//go:build windows
+
+package processscraper // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/processscraper"
+
+import (
+	"context"
+	"fmt"
+	"unsafe"
+
+	"github.com/shirou/gopsutil/v4/process"
+	"go.opentelemetry.io/collector/featuregate"
+	"golang.org/x/sys/windows"
+)
+
+var useNewGetProcessHandles = featuregate.GlobalRegistry().MustRegister(
+	"hostmetrics.process.onWindowsUseNewGetProcesses",
+	featuregate.StageBeta,
+	featuregate.WithRegisterDescription("If disabled, the scraper will use the legacy implementation to retrieve process handles."),
+)
+
+func getGopsutilProcessHandles(ctx context.Context) (processHandles, error) {
+	if !useNewGetProcessHandles.IsEnabled() {
+		return getGopsutilProcessHandlesLegacy(ctx)
+	}
+
+	snap, err := windows.CreateToolhelp32Snapshot(windows.TH32CS_SNAPPROCESS, 0)
+	if err != nil {
+		return nil, fmt.Errorf("could not create snapshot: %w", err)
+	}
+	defer func() {
+		_ = windows.CloseHandle(snap)
+	}()
+
+	var pe32 windows.ProcessEntry32
+	pe32.Size = uint32(unsafe.Sizeof(pe32))
+	if err = windows.Process32First(snap, &pe32); err != nil {
+		return nil, fmt.Errorf("could not get first process: %w", err)
+	}
+
+	wrappedProcesses := make([]wrappedProcessHandle, 0, 64)
+	for {
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		default:
+			// Ignoring any errors here to keep same behavior as the legacy implementation
+			// based on the `process.ProcessesWithContext` from the `gopsutil` package.
+			p, _ := process.NewProcess(int32(pe32.ProcessID))
+			if p != nil {
+				wrappedProcess := wrappedProcessHandle{
+					Process:           p,
+					parentPid:         int32(pe32.ParentProcessID),
+					initialNumThreads: int32(pe32.Threads),
+					flags:             flagParentPidSet | flagUseInitialNumThreadsOnce,
+				}
+				wrappedProcesses = append(wrappedProcesses, wrappedProcess)
+			}
+		}
+
+		if err = windows.Process32Next(snap, &pe32); err != nil {
+			break
+		}
+	}
+
+	return &gopsProcessHandles{handles: wrappedProcesses}, nil
+}
+
+func getGopsutilProcessHandlesLegacy(ctx context.Context) (processHandles, error) {
+	processes, err := process.ProcessesWithContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+	wrapped := make([]wrappedProcessHandle, len(processes))
+	for i, p := range processes {
+		wrapped[i] = wrappedProcessHandle{
+			Process: p,
+		}
+	}
+
+	return &gopsProcessHandles{handles: wrapped}, nil
+}

receiver/hostmetricsreceiver/internal/scraper/processscraper/process.go

@@ -109,18 +109,26 @@ func (p *gopsProcessHandles) Pid(index int) int32 {
 }
 
 func (p *gopsProcessHandles) At(index int) processHandle {
-	return p.handles[index]
+	return &(p.handles[index])
 }
 
 func (p *gopsProcessHandles) Len() int {
 	return len(p.handles)
 }
 
+const (
+	flagParentPidSet             = 1 << 0
+	flagUseInitialNumThreadsOnce = 1 << 1
+)
+
 type wrappedProcessHandle struct {
 	*process.Process
+	parentPid         int32
+	initialNumThreads int32
+	flags             uint8 // bitfield to track if fields are set
 }
 
-func (p wrappedProcessHandle) CgroupWithContext(ctx context.Context) (string, error) {
+func (p *wrappedProcessHandle) CgroupWithContext(ctx context.Context) (string, error) {
 	pid := p.Process.Pid
 	statPath := getEnvWithContext(ctx, string(common.HostProcEnvKey), "/proc", strconv.Itoa(int(pid)), "cgroup")
 	contents, err := os.ReadFile(statPath)
@@ -131,6 +139,36 @@ func (p wrappedProcessHandle) CgroupWithContext(ctx context.Context) (string, er
 	return strings.TrimSuffix(string(contents), "\n"), nil
 }
 
+func (p *wrappedProcessHandle) PpidWithContext(ctx context.Context) (int32, error) {
+	if p.flags&flagParentPidSet != 0 {
+		return p.parentPid, nil
+	}
+
+	parentPid, err := p.Process.PpidWithContext(ctx)
+	if err != nil {
+		return 0, err
+	}
+
+	p.parentPid = parentPid
+	p.flags |= flagParentPidSet
+	return parentPid, nil
+}
+
+func (p *wrappedProcessHandle) NumThreadsWithContext(ctx context.Context) (int32, error) {
+	if p.flags&flagUseInitialNumThreadsOnce != 0 {
+		// The number of threads can fluctuate so use the initially cached value only the first time.
+		p.flags &^= flagUseInitialNumThreadsOnce
+		return p.initialNumThreads, nil
+	}
+
+	numThreads, err := p.Process.NumThreadsWithContext(ctx)
+	if err != nil {
+		return 0, err
+	}
+
+	return numThreads, nil
+}
+
 // copied from gopsutil:
 // GetEnvWithContext retrieves the environment variable key. If it does not exist it returns the default.
 // The context may optionally contain a map superseding os.EnvKey.
@@ -150,19 +188,6 @@ func getEnvWithContext(ctx context.Context, key string, dfault string, combineWi
 	return filepath.Join(segments...)
 }
 
-func getProcessHandlesInternal(ctx context.Context) (processHandles, error) {
-	processes, err := process.ProcessesWithContext(ctx)
-	if err != nil {
-		return nil, err
-	}
-	wrapped := make([]wrappedProcessHandle, len(processes))
-	for i, p := range processes {
-		wrapped[i] = wrappedProcessHandle{Process: p}
-	}
-
-	return &gopsProcessHandles{handles: wrapped}, nil
-}
-
 func parentPid(ctx context.Context, handle processHandle, pid int32) (int32, error) {
 	// special case for pid 0 and pid 1 in darwin
 	if pid == 0 || (pid == 1 && runtime.GOOS == "darwin") {

receiver/hostmetricsreceiver/internal/scraper/processscraper/process_metadata_benchmark_test.go

@@ -0,0 +1,65 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+//go:build windows
+
+package processscraper
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/featuregate"
+	"go.opentelemetry.io/collector/scraper"
+)
+
+func BenchmarkGetProcessMetadata(b *testing.B) {
+	ctx := context.Background()
+	config := &Config{}
+
+	scraper, err := newProcessScraper(scraper.Settings{}, config)
+	if err != nil {
+		b.Fatalf("Failed to create process scraper: %v", err)
+	}
+
+	benchmarks := []struct {
+		name             string
+		useLegacy        bool
+		parentPidEnabled bool
+	}{
+		{
+			name: "New-ExcludeParentPid",
+		},
+		{
+			name:      "Old-ExcludeParentPid",
+			useLegacy: true,
+		},
+		{
+			name:             "New-IncludeParentPid",
+			parentPidEnabled: true,
+		},
+		{
+			name:             "Old-IncludeParentPid",
+			parentPidEnabled: true,
+			useLegacy:        true,
+		},
+	}
+
+	for _, bm := range benchmarks {
+		b.Run(bm.name, func(b *testing.B) {
+			// Set feature gate value
+			previousValue := useNewGetProcessHandles.IsEnabled()
+			require.NoError(b, featuregate.GlobalRegistry().Set(useNewGetProcessHandles.ID(), !bm.useLegacy))
+			defer func() {
+				require.NoError(b, featuregate.GlobalRegistry().Set(useNewGetProcessHandles.ID(), previousValue))
+			}()
+			scraper.config.MetricsBuilderConfig.ResourceAttributes.ProcessParentPid.Enabled = bm.parentPidEnabled
+
+			for i := 0; i < b.N; i++ {
+				// Typically there are errors, but we are not interested in them for this benchmark
+				_, _ = scraper.getProcessMetadata(ctx)
+			}
+		})
+	}
+}

receiver/hostmetricsreceiver/internal/scraper/processscraper/process_scraper.go

@@ -66,7 +66,7 @@ func newProcessScraper(settings scraper.Settings, cfg *Config) (*processScraper,
 		settings:             settings,
 		config:               cfg,
 		getProcessCreateTime: processHandle.CreateTimeWithContext,
-		getProcessHandles:    getProcessHandlesInternal,
+		getProcessHandles:    getGopsutilProcessHandles,
 		scrapeProcessDelay:   cfg.ScrapeProcessDelay,
 		ucals:                make(map[int32]*ucal.CPUUtilizationCalculator),
 		handleCountManager:   handlecount.NewManager(),
@@ -271,14 +271,17 @@ func (s *processScraper) getProcessMetadata(ctx context.Context) ([]*processMeta
 			continue
 		}
 
-		parentPid, err := parentPid(ctx, handle, pid)
-		if err != nil {
-			errs.AddPartial(0, fmt.Errorf("error reading parent pid for process %q (pid %v): %w", executable.name, pid, err))
+		parentProcessID := int32(0)
+		if s.config.MetricsBuilderConfig.ResourceAttributes.ProcessParentPid.Enabled {
+			parentProcessID, err = parentPid(ctx, handle, pid)
+			if err != nil {
+				errs.AddPartial(0, fmt.Errorf("error reading parent pid for process %q (pid %v): %w", executable.name, pid, err))
+			}
 		}
 
 		md := &processMetadata{
 			pid:        pid,
-			parentPid:  parentPid,
+			parentPid:  parentProcessID,
 			executable: executable,
 			command:    command,
 			username:   username,