Merge pull request #1194 from hashicorp/ceb-debug

cmd/waypoint-entrypoint: dump heap profile on SIGUSR1

cmd/waypoint-entrypoint/debug.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+ "context"
+ "fmt"
+ "os"
+ "os/signal"
+ "path/filepath"
+ "runtime/pprof"
+ "time"
+
+ "github.com/hashicorp/go-hclog"
+ "golang.org/x/sys/unix"
+)
+
+// debugSignalHandler writes a heap profile to the system temporary
+// directory when SIGUSR1 is received. The output path for each dump
+// is logged.
+//
+// NOTE(mitchellh): In the future, I expect that we'll dump a lot more
+// data and perhaps store a tar file or some other format. Given the
+// debug nature of this file, I'm not going to worry too much about tagging
+// the file type and so on.
+func debugSignalHandler(ctx context.Context, log hclog.Logger) {
+ ch := make(chan os.Signal, 1)
+ signal.Notify(ch, unix.SIGUSR1)
+ defer signal.Stop(ch)
+
+ for {
+ select {
+ case <-ctx.Done():
+ return
+
+ case <-ch:
+ }
+
+ // Dump the profile to a timestamped file
+ path := filepath.Join(os.TempDir(), fmt.Sprintf(
+ "waypoint_heap_%d", time.Now().Unix()))
+ log.Warn("SIGUSR1 received, dumping heap profile", "path", path)
+
+ // Get the profile, this is predefined by Go and should always exist.
+ profile := pprof.Lookup("heap")
+ if profile == nil {
+ log.Error("heap profile not found, this should not be possible")
+ continue
+ }
+
+ // Write it
+ f, err := os.Create(path)
+ if err != nil {
+ log.Error("error opening file to dump profile", "err", err)
+ continue
+ }
+ err = profile.WriteTo(f, 0)
+ f.Close()
+ if err != nil {
+ log.Error("error writing heap profile", "err", err)
+ }
+ }
+}

cmd/waypoint-entrypoint/main.go

@@ -37,6 +37,9 @@ func realMain() int {
  ctx, closer := signalcontext.WithInterrupt(context.Background(), log)
  defer closer()
 
+ // Start our debug signal handler
+ go debugSignalHandler(ctx, log.Named("debug"))
+
  // Run our core logic
  err := ceb.Run(ctx,
  ceb.WithEnvDefaults(),