Spew debugging

Signed-off-by: John Howard <jhoward@microsoft.com>

daemon/daemon.go

@@ -476,10 +476,6 @@ func NewDaemon(config *Config, registryService registry.Service, containerdRemot
 		return nil, err
 	}
 
-	// set up SIGUSR1 handler on Unix-like systems, or a Win32 global event
-	// on Windows to dump Go routine stacks
-	setupDumpStackTrap(config.Root)
-
 	uidMaps, gidMaps, err := setupRemappedRoot(config)
 	if err != nil {
 		return nil, err
@@ -699,6 +695,10 @@ func NewDaemon(config *Config, registryService registry.Service, containerdRemot
 	engineCpus.Set(float64(info.NCPU))
 	engineMemory.Set(float64(info.MemTotal))
 
+	// set up SIGUSR1 handler on Unix-like systems, or a Win32 global event
+	// on Windows to dump Go routine stacks
+	d.setupDumpStackTrap(config.Root)
+
 	return d, nil
 }
 

daemon/debugtrap.go

@@ -0,0 +1,33 @@
+package daemon
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/davecgh/go-spew/spew"
+	"github.com/pkg/errors"
+)
+
+const dataStructuresLogNameTemplate = "daemon-data-%s.log"
+
+// dumpDaemon appends the daemon datastructures into file in dir and returns full path
+// to that file.
+func (d *Daemon) dumpDaemon(dir string) (string, error) {
+	// Ensure we recover from a panic as we are doing this without any locking
+	defer func() {
+		recover()
+	}()
+
+	path := filepath.Join(dir, fmt.Sprintf(dataStructuresLogNameTemplate, strings.Replace(time.Now().Format(time.RFC3339), ":", "", -1)))
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0666)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to open file to write the daemon datastructure dump")
+	}
+	defer f.Close()
+	spew.Fdump(f, d) // Does not return an error
+	f.Sync()
+	return path, nil
+}

daemon/debugtrap_unix.go

@@ -7,12 +7,11 @@ import (
 	"os/signal"
 	"syscall"
 
-	stackdump "github.com/docker/docker/pkg/signal"
-
 	"github.com/Sirupsen/logrus"
+	stackdump "github.com/docker/docker/pkg/signal"
 )
 
-func setupDumpStackTrap(root string) {
+func (d *Daemon) setupDumpStackTrap(root string) {
 	c := make(chan os.Signal, 1)
 	signal.Notify(c, syscall.SIGUSR1)
 	go func() {
@@ -20,9 +19,15 @@ func setupDumpStackTrap(root string) {
 			path, err := stackdump.DumpStacks(root)
 			if err != nil {
 				logrus.WithError(err).Error("failed to write goroutines dump")
-				continue
+			} else {
+				logrus.Infof("goroutine stacks written to %s", path)
+			}
+			path, err = d.dumpDaemon(root)
+			if err != nil {
+				logrus.WithError(err).Error("failed to write daemon datastructure dump")
+			} else {
+				logrus.Infof("daemon datastructure dump written to %s", path)
 			}
-			logrus.Infof("goroutine stacks written to %s", path)
 		}
 	}()
 }

daemon/debugtrap_unsupported.go

@@ -2,6 +2,6 @@
 
 package daemon
 
-func setupDumpStackTrap(_ string) {
+func (d *Daemon) setupDumpStackTrap(_ string) {
 	return
 }

daemon/debugtrap_windows.go

@@ -12,7 +12,7 @@ import (
 	"github.com/docker/docker/pkg/system"
 )
 
-func setupDumpStackTrap(root string) {
+func (d *Daemon) setupDumpStackTrap(root string) {
 	// Windows does not support signals like *nix systems. So instead of
 	// trapping on SIGUSR1 to dump stacks, we wait on a Win32 event to be
 	// signaled. ACL'd to builtin administrators and local system
@@ -38,9 +38,15 @@ func setupDumpStackTrap(root string) {
 			path, err := signal.DumpStacks(root)
 			if err != nil {
 				logrus.WithError(err).Error("failed to write goroutines dump")
-				continue
+			} else {
+				logrus.Infof("goroutine stacks written to %s", path)
+			}
+			path, err = d.dumpDaemon(root)
+			if err != nil {
+				logrus.WithError(err).Error("failed to write daemon datastructure dump")
+			} else {
+				logrus.Infof("daemon datastructure dump written to %s", path)
 			}
-			logrus.Infof("goroutine stacks written to %s", path)
 		}
 	}()
 }

pkg/signal/trap.go

@@ -6,6 +6,7 @@ import (
 	gosignal "os/signal"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"sync/atomic"
 	"syscall"
 	"time"
@@ -82,7 +83,7 @@ func DumpStacks(dir string) (string, error) {
 		bufferLen *= 2
 	}
 	buf = buf[:stackSize]
-	path := filepath.Join(dir, fmt.Sprintf(stacksLogNameTemplate, time.Now().Format(time.RFC3339)))
+	path := filepath.Join(dir, fmt.Sprintf(stacksLogNameTemplate, strings.Replace(time.Now().Format(time.RFC3339), ":", "", -1)))
 	f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0666)
 	if err != nil {
 		return "", errors.Wrap(err, "failed to open file to write the goroutine stacks")