Log trace_pipe only when debug mode

ebpf/gmon.go

@@ -1,14 +1,10 @@
 package ebpf
 
 import (
- "bufio"
  "context"
  "errors"
  "fmt"
- "io/fs"
  "log/slog"
- "os"
- "strings"
 
  "github.com/cilium/ebpf"
  "github.com/cilium/ebpf/link"
@@ -28,7 +24,6 @@ func Run(ctx context.Context, config Config) (func(), error) {
  if err != nil {
  return func() {}, err
  }
- go logTracePipe(ctx.Done())
  ex, err := link.OpenExecutable(config.binPath)
  if err != nil {
  return func() {}, err
@@ -117,30 +112,3 @@ func linkUprobe(
  slog.Debug("attach uprobe with address", slog.String("symbol", symbol), slog.String("address", fmt.Sprintf("%#x", address)))
  return l, nil
 }
-
-func logTracePipe(done <-chan struct{}) {
- tracePipe, err := os.Open("/sys/kernel/debug/tracing/trace_pipe")
- if err != nil {
- slog.Error("open trace_pipe", slog.Any("error", err))
- return
- }
- defer tracePipe.Close()
-
- go func() {
- // Create a bufio.Scanner to read the trace data.
- scanner := bufio.NewScanner(tracePipe)
- // Read and print the trace data.
- for scanner.Scan() {
- msg := strings.TrimSpace(scanner.Text())
- if strings.Contains(msg, "gmon") {
- slog.Warn(msg)
- }
- }
- if err := scanner.Err(); err != nil {
- if !errors.Is(err, fs.ErrClosed) {
- slog.Error("read trace_pipe", slog.Any("error", err))
- }
- }
- }()
- <-done
-}

main.go

@@ -1,9 +1,12 @@
 package main
 
 import (
+ "bufio"
  "context"
+ "errors"
  "flag"
  "fmt"
+ "io/fs"
  "log"
  "log/slog"
  "net/http"
@@ -12,6 +15,7 @@ import (
  "os/signal"
  "runtime"
  "runtime/trace"
+ "strings"
 
  "github.com/cilium/ebpf/rlimit"
  "github.com/keisku/gmon/ebpf"
@@ -96,6 +100,9 @@ func main() {
  if err != nil {
  errlog.Fatalln(err)
  }
+ if levelMap[*level] == slog.LevelDebug {
+ go logTracePipe(ctx.Done())
+ }
  if 1023 < *pprofPort {
  go func() {
  _ = http.ListenAndServe(fmt.Sprintf("127.0.0.1:%d", pprofPort), nil)
@@ -105,3 +112,28 @@ func main() {
  slog.Debug("gmon exits")
  eBPFClose()
 }
+
+func logTracePipe(done <-chan struct{}) {
+ tracePipe, err := os.Open("/sys/kernel/debug/tracing/trace_pipe")
+ if err != nil {
+ slog.Error("open trace_pipe", slog.Any("error", err))
+ return
+ }
+ defer tracePipe.Close()
+
+ go func() {
+ scanner := bufio.NewScanner(tracePipe)
+ for scanner.Scan() {
+ msg := strings.TrimSpace(scanner.Text())
+ if strings.Contains(msg, "gmon") {
+ slog.Debug(msg)
+ }
+ }
+ if err := scanner.Err(); err != nil {
+ if !errors.Is(err, fs.ErrClosed) {
+ slog.Error("read trace_pipe", slog.Any("error", err))
+ }
+ }
+ }()
+ <-done
+}