@@ -731,6 +731,7 @@ func NewDaemon(config *Config, registryService *registry.Service) (daemon *Daemo

 	d.RegistryService = registryService

 	d.EventsService = eventsService

 	d.root = config.Root

+	go d.execCommandGC()

 	if err := d.restore(); err != nil {

 		return nil, err

@@ -6,6 +6,7 @@ import (

 	"io/ioutil"

 	"strings"

 	"sync"

+	"time"

 	"github.com/Sirupsen/logrus"

 	"github.com/docker/docker/daemon/execdriver"

@@ -247,3 +248,34 @@ func (d *Daemon) Exec(c *Container, execConfig *execConfig, pipes *execdriver.Pi

 	return exitStatus, err

 }

+

+// execCommandGC runs a ticker to clean up the daemon references

+// of exec configs that are no longer part of the container.

+func (d *Daemon) execCommandGC() {

+	for range time.Tick(5 * time.Minute) {

+		var (

+			cleaned          int

+			liveExecCommands = d.containerExecIds()

+			ids              = d.execCommands.List()

+		)

+		for _, id := range ids {

+			if _, exists := liveExecCommands[id]; !exists {

+				cleaned++

+				d.execCommands.Delete(id)

+			}

+		}

+		logrus.Debugf("clean %d unused exec commands", cleaned)

+	}

+}

+

+// containerExecIds returns a list of all the current exec ids that are in use

+// and running inside a container.

+func (d *Daemon) containerExecIds() map[string]struct{} {

+	ids := map[string]struct{}{}

+	for _, c := range d.containers.List() {

+		for _, id := range c.execCommands.List() {

+			ids[id] = struct{}{}

+		}

+	}

+	return ids

+}