Don't deepcopy job when retrieving copy of Alloc

This PR removes deepcopying of the job attached to the allocation in the
alloc runner. This operation is called very often so removing reflect
from the code path and the potentially large number of mallocs need to
create a job reduced memory and cpu pressure.

client/alloc_runner.go

@@ -279,8 +279,17 @@ func copyTaskStates(states map[string]*structs.TaskState) map[string]*structs.Ta
 // Alloc returns the associated allocation
 func (r *AllocRunner) Alloc() *structs.Allocation {
 	r.allocLock.Lock()
+
+	// Clear the job before copying
+	job := r.alloc.Job
+	r.alloc.Job = nil
+
 	alloc := r.alloc.Copy()
 
+	// Restore
+	r.alloc.Job = job
+	alloc.Job = job
+
 	// The status has explicitly been set.
 	if r.allocClientStatus != "" || r.allocClientDescription != "" {
 		alloc.ClientStatus = r.allocClientStatus

client/util.go

@@ -1,6 +1,7 @@
 package client
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -9,6 +10,7 @@ import (
 	"path/filepath"
 
 	"github.com/hashicorp/nomad/nomad/structs"
+	"github.com/ugorji/go/codec"
 )
 
 type allocTuple struct {
@@ -78,15 +80,17 @@ func shuffleStrings(list []string) {
 
 // persistState is used to help with saving state
 func persistState(path string, data interface{}) error {
-	buf, err := json.Marshal(data)
-	if err != nil {
-		return fmt.Errorf("failed to encode state: %v", err)
+	var buf bytes.Buffer
+	enc := codec.NewEncoder(&buf, structs.JsonHandlePretty)
+	if err := enc.Encode(data); err != nil {
+		return err
 	}
+
 	if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil {
 		return fmt.Errorf("failed to make dirs for %s: %v", path, err)
 	}
 	tmpPath := path + ".tmp"
-	if err := ioutil.WriteFile(tmpPath, buf, 0600); err != nil {
+	if err := ioutil.WriteFile(tmpPath, buf.Bytes(), 0600); err != nil {
 		return fmt.Errorf("failed to save state to tmp: %v", err)
 	}
 	if err := os.Rename(tmpPath, path); err != nil {

command/agent/fs_endpoint.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/docker/docker/pkg/ioutils"
 	"github.com/hashicorp/nomad/client/allocdir"
+	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hpcloud/tail/watch"
 	"github.com/ugorji/go/codec"
 )
@@ -290,7 +291,7 @@ func NewStreamFramer(out io.WriteCloser, plainTxt bool,
 	heartbeatRate, batchWindow time.Duration, frameSize int) *StreamFramer {
 
 	// Create a JSON encoder
-	enc := codec.NewEncoder(out, jsonHandle)
+	enc := codec.NewEncoder(out, structs.JsonHandle)
 
 	// Create the heartbeat and flush ticker
 	heartbeat := time.NewTicker(heartbeatRate)

command/agent/http.go

@@ -29,18 +29,6 @@ const (
 	scadaHTTPAddr = "SCADA"
 )
 
-var (
-	// jsonHandle and jsonHandlePretty are the codec handles to JSON encode
-	// structs. The pretty handle will add indents for easier human consumption.
-	jsonHandle = &codec.JsonHandle{
-		HTMLCharsAsIs: true,
-	}
-	jsonHandlePretty = &codec.JsonHandle{
-		HTMLCharsAsIs: true,
-		Indent:        4,
-	}
-)
-
 // HTTPServer is used to wrap an Agent and expose it over an HTTP interface
 type HTTPServer struct {
 	agent    *Agent
@@ -248,13 +236,13 @@ func (s *HTTPServer) wrap(handler func(resp http.ResponseWriter, req *http.Reque
 		if obj != nil {
 			var buf bytes.Buffer
 			if prettyPrint {
-				enc := codec.NewEncoder(&buf, jsonHandlePretty)
+				enc := codec.NewEncoder(&buf, structs.JsonHandlePretty)
 				err = enc.Encode(obj)
 				if err == nil {
 					buf.Write([]byte("\n"))
 				}
 			} else {
-				enc := codec.NewEncoder(&buf, jsonHandle)
+				enc := codec.NewEncoder(&buf, structs.JsonHandle)
 				err = enc.Encode(obj)
 			}
 			if err != nil {

nomad/structs/structs.go

@@ -4231,6 +4231,18 @@ var MsgpackHandle = func() *codec.MsgpackHandle {
 	return h
 }()
 
+var (
+	// JsonHandle and JsonHandlePretty are the codec handles to JSON encode
+	// structs. The pretty handle will add indents for easier human consumption.
+	JsonHandle = &codec.JsonHandle{
+		HTMLCharsAsIs: true,
+	}
+	JsonHandlePretty = &codec.JsonHandle{
+		HTMLCharsAsIs: true,
+		Indent:        4,
+	}
+)
+
 var HashiMsgpackHandle = func() *hcodec.MsgpackHandle {
 	h := &hcodec.MsgpackHandle{RawToString: true}