diff --git a/services/syncbase/vsync/dag.go b/services/syncbase/vsync/dag.go
index 2caa50d..1d0eacd 100644
--- a/services/syncbase/vsync/dag.go
+++ b/services/syncbase/vsync/dag.go
@@ -113,8 +113,14 @@
 // batchSet holds information on a set of write batches.
 type batchSet map[uint64]*batchInfo
 
-// graftMap holds the state of DAG node grafting (attaching) per object.
-type graftMap map[string]*graftInfo
+// graftMap holds the state of DAG node grafting (attaching) per object.  It
+// holds a store handle to use when reading the object heads during grafting
+// operations.  This avoids contaminating the transaction read-set of the
+// caller (typically the Initiator storing newly received deltas).
+type graftMap struct {
+	objGraft map[string]*graftInfo
+	st       store.Store
+}
 
 // graftInfo holds the state of an object's node grafting in the DAG.
 // It is ephemeral (in-memory), used during a single sync operation to track
@@ -247,7 +253,7 @@
 //
 // The grafting structure is not needed when nodes are being added locally by
 // the Watcher, passing a nil grafting structure.
-func (s *syncService) addNode(ctx *context.T, tx store.Transaction, oid, version, logrec string, deleted bool, parents []string, btid uint64, graft graftMap) error {
+func (s *syncService) addNode(ctx *context.T, tx store.Transaction, oid, version, logrec string, deleted bool, parents []string, btid uint64, graft *graftMap) error {
 	if parents != nil {
 		if len(parents) > 2 {
 			return verror.New(verror.ErrInternal, ctx, "cannot have more than 2 parents")
@@ -347,7 +353,7 @@
 // to track DAG attachements during a sync operation.  It is not needed if the
 // parent linkage is due to a local change (from conflict resolution selecting
 // an existing version).
-func (s *syncService) addParent(ctx *context.T, tx store.Transaction, oid, version, parent string, graft graftMap) error {
+func (s *syncService) addParent(ctx *context.T, tx store.Transaction, oid, version, parent string, graft *graftMap) error {
 	if version == parent {
 		return verror.New(verror.ErrInternal, ctx, "object", oid, version, "cannot be its own parent")
 	}
@@ -435,7 +441,7 @@
 // head is different from the current local head. If there is a single new-head
 // and the snapshot head is the same as the current local head, the object
 // changes were applied without triggering a conflict.
-func hasConflict(ctx *context.T, st store.StoreReader, oid string, graft graftMap) (isConflict bool, newHead, oldHead, ancestor string, err error) {
+func hasConflict(ctx *context.T, st store.StoreReader, oid string, graft *graftMap) (isConflict bool, newHead, oldHead, ancestor string, err error) {
 	isConflict = false
 	oldHead = NoVersion
 	newHead = NoVersion
@@ -447,7 +453,7 @@
 		return
 	}
 
-	info := graft[oid]
+	info := graft.objGraft[oid]
 	if info == nil {
 		err = verror.New(verror.ErrInternal, ctx, "node", oid, "has no DAG graft info")
 		return
@@ -521,18 +527,22 @@
 	return
 }
 
-// newGraft allocates a graftMap to track DAG node grafting during sync.
-func newGraft() graftMap {
-	return make(graftMap)
+// newGraft allocates a graftMap to track DAG node grafting during sync.  It is
+// given a handle to a store to use for its own reading of object head nodes.
+func newGraft(st store.Store) *graftMap {
+	return &graftMap{
+		objGraft: make(map[string]*graftInfo),
+		st:       st,
+	}
 }
 
 // getObjectGraft returns the graftInfo for an object ID.  If the graftMap is
 // nil, a nil graftInfo is returned because grafting is not being tracked.
-func getObjectGraftInfo(ctx *context.T, sntx store.SnapshotOrTransaction, graft graftMap, oid string) *graftInfo {
+func getObjectGraftInfo(ctx *context.T, sntx store.SnapshotOrTransaction, graft *graftMap, oid string) *graftInfo {
 	if graft == nil {
 		return nil
 	}
-	if info := graft[oid]; info != nil {
+	if info := graft.objGraft[oid]; info != nil {
 		return info
 	}
 
@@ -543,12 +553,20 @@
 	}
 
 	// If the object has a head node, include it in the set of new heads.
-	if head, err := getHead(ctx, sntx, oid); err == nil {
+	// Note: use the store handle of the graftMap if available to avoid
+	// contaminating the read-set of the caller's transaction.  Otherwise
+	// use the caller's transaction.
+	var st store.StoreReader
+	st = graft.st
+	if st == nil {
+		st = sntx
+	}
+	if head, err := getHead(ctx, st, oid); err == nil {
 		info.newHeads[head] = true
 		info.oldHeadSnap = head
 	}
 
-	graft[oid] = info
+	graft.objGraft[oid] = info
 	return info
 }
 
@@ -818,15 +836,15 @@
 // getParentMap is a testing and debug helper function that returns for an
 // object a map of its DAG (node-to-parents relations).  If a graft structure
 // is given, include its fragments in the map.
-func getParentMap(ctx *context.T, st store.StoreReader, oid string, graft graftMap) map[string][]string {
+func getParentMap(ctx *context.T, st store.StoreReader, oid string, graft *graftMap) map[string][]string {
 	parentMap := make(map[string][]string)
 	var start []string
 
 	if head, err := getHead(ctx, st, oid); err == nil {
 		start = append(start, head)
 	}
-	if graft != nil && graft[oid] != nil {
-		for v := range graft[oid].newHeads {
+	if graft != nil && graft.objGraft[oid] != nil {
+		for v := range graft.objGraft[oid].newHeads {
 			start = append(start, v)
 		}
 	}
diff --git a/services/syncbase/vsync/dag_test.go b/services/syncbase/vsync/dag_test.go
index 57291a4..709df1c 100644
--- a/services/syncbase/vsync/dag_test.go
+++ b/services/syncbase/vsync/dag_test.go
@@ -128,7 +128,7 @@
 	}
 	tx.Commit()
 
-	graft := newGraft()
+	graft := newGraft(st)
 	tx = st.NewTransaction()
 	if err := s.addParent(nil, tx, oid, version, version, graft); err == nil {
 		t.Errorf("addParent() did not fail on a self-parent for object %s:%s", oid, version)
@@ -154,7 +154,7 @@
 		}
 		tx.Commit()
 
-		var g graftMap
+		var g *graftMap
 		if remote {
 			g = graft
 		}
@@ -311,7 +311,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"3": true}
 
@@ -388,7 +388,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"6": true}
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
@@ -471,7 +471,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"3": true, "6": true}
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
@@ -564,7 +564,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"3": true, "6": true}
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
@@ -651,7 +651,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"3": true, "6": true}
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
@@ -956,7 +956,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"3": true}
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
@@ -981,7 +981,7 @@
 		t.Errorf("hasConflict() on %v did not fail with a nil graft map: flag %t, newHead %s, oldHead %s, ancestor %s, err %v",
 			oid, isConflict, newHead, oldHead, ancestor, errConflict)
 	}
-	isConflict, newHead, oldHead, ancestor, errConflict = hasConflict(nil, st, oid, newGraft())
+	isConflict, newHead, oldHead, ancestor, errConflict = hasConflict(nil, st, oid, newGraft(st))
 	if errConflict == nil {
 		t.Errorf("hasConflict() on %v did not fail with an empty graft map: flag %t, newHead %s, oldHead %s, ancestor %s, err %v",
 			oid, isConflict, newHead, oldHead, ancestor, errConflict)
@@ -1026,7 +1026,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"3": true, "4": true}
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
@@ -1086,7 +1086,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"4": true}
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
@@ -1148,7 +1148,7 @@
 	}
 
 	// Verify the grafting of remote nodes.
-	g := graft[oid]
+	g := graft.objGraft[oid]
 
 	expNewHeads := map[string]bool{"5": true}
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
@@ -1185,7 +1185,7 @@
 		t.Errorf("object %s has wrong head: %s", oid, head)
 	}
 
-	g = graft[oid]
+	g = graft.objGraft[oid]
 
 	if !reflect.DeepEqual(g.newHeads, expNewHeads) {
 		t.Errorf("object %s has invalid newHeads: (%v) instead of (%v)", oid, g.newHeads, expNewHeads)
diff --git a/services/syncbase/vsync/initiator.go b/services/syncbase/vsync/initiator.go
index 5875e21..94f79e1 100644
--- a/services/syncbase/vsync/initiator.go
+++ b/services/syncbase/vsync/initiator.go
@@ -180,7 +180,7 @@
 	remote     interfaces.GenVector         // generation vector from the remote peer.
 	updLocal   interfaces.GenVector         // updated local generation vector at the end of sync round.
 	updObjects map[string]*objConflictState // tracks updated objects during a log replay.
-	dagGraft   graftMap                     // DAG state that tracks conflicts and common ancestors.
+	dagGraft   *graftMap                    // DAG state that tracks conflicts and common ancestors.
 
 	req    interfaces.DeltaReq                // GetDeltas RPC request.
 	stream interfaces.SyncGetDeltasClientCall // stream handle for the GetDeltas RPC.
@@ -243,7 +243,7 @@
 	iSt := &initiationState{}
 	iSt.config = c
 	iSt.updObjects = make(map[string]*objConflictState)
-	iSt.dagGraft = newGraft()
+	iSt.dagGraft = newGraft(c.st)
 	iSt.sg = sg
 	return iSt
 }
@@ -436,18 +436,6 @@
 // resolution during replay.  This avoids resolving conflicts that have already
 // been resolved by other devices.
 func (iSt *initiationState) recvAndProcessDeltas(ctx *context.T) error {
-	// This is to handle issues with graftMap in DAG. Ideally, the
-	// transaction created to store all the deltas received over the network
-	// should not contend with any other store changes since this is all
-	// brand new information. However, as log records are received over the
-	// network, they are also incrementally processed. To enable incremental
-	// processing, the current head of each dirty object is read to populate
-	// the graftMap. This read can potentially contend with the watcher
-	// updating the head of an object. This lock prevents that contention in
-	// order to avoid retrying the whole transaction.
-	iSt.config.sync.thLock.Lock()
-	defer iSt.config.sync.thLock.Unlock()
-
 	// TODO(hpucha): This works for now, but figure out a long term solution
 	// as this may be implementation dependent. It currently works because
 	// the RecvStream call is stateless, and grabbing a handle to it
diff --git a/services/syncbase/vsync/replay_test.go b/services/syncbase/vsync/replay_test.go
index e13eab6..272b945 100644
--- a/services/syncbase/vsync/replay_test.go
+++ b/services/syncbase/vsync/replay_test.go
@@ -179,14 +179,14 @@
 
 // dagReplayCommands parses a sync test file and replays its commands, updating
 // the DAG structures associated with the sync service.
-func (s *syncService) dagReplayCommands(ctx *context.T, syncfile string) (graftMap, error) {
+func (s *syncService) dagReplayCommands(ctx *context.T, syncfile string) (*graftMap, error) {
 	cmds, err := parseSyncCommands(syncfile)
 	if err != nil {
 		return nil, err
 	}
 
 	st := s.sv.St()
-	graft := newGraft()
+	graft := newGraft(st)
 
 	for _, cmd := range cmds {
 		tx := st.NewTransaction()