diff --git a/src/deptree.cpp b/src/deptree.cpp
index 5f80f58..1f8597b 100644
--- a/src/deptree.cpp
+++ b/src/deptree.cpp
@@ -1,3 +1,4 @@
+#include <stack>
 #include "deptree.h"
 
 int DepTree::CreateNodeFromVar(const std::string& var, UsedType& used, CallStack& callstack)
@@ -142,3 +143,198 @@ DepTree* DepTree::FindNodeByVar(const std::string& var) const
  while(curnode->parents.size()!=0) curnode=*(curnode->parents.begin());
  return curnode->FindNodeByVarFromCurrent(var);
 }
+
+
+DepTree::LeafVector DepTree::FindLeafNodes() const
+{
+ LeafVector leafs;
+ std::stack<NodeVector::const_iterator> path,ends;
+ NodeVector::const_iterator it,end;
+ // define isvisited as reversion of last visited
+ bool isvisited=!visited;
+ // ascending to root
+ const DepTree* root=this;
+ while(root->parents.size()!=0) root=*(root->parents.begin());
+
+ const DepTree* curnode=root;
+ curnode->visited=isvisited;
+ it=curnode->childrens.begin();
+ end=curnode->childrens.end();
+
+ while(true)
+ {
+  if(it!=end)
+  {
+   if((*it)->visited==isvisited) {it++; continue;}
+   path.push(it); ends.push(end);
+   curnode=(*it);
+   curnode->visited=isvisited;
+   it=curnode->childrens.begin();
+   end=curnode->childrens.end();
+   if(it==end) leafs.push_back(const_cast<DepTree*>(curnode));
+  }
+  else
+  {
+   if(path.size()==0) break;
+   it=path.top(); path.pop();
+   end=ends.top(); ends.pop();
+   it++;
+  }
+ }
+
+ return leafs;
+}
+
+
+// Multi-threaded version
+void TreeEvaluate(std::mutex* mtx, int* errflag, DepTree::LeafVector* leafs, const DepTree* root)
+{
+ // mtx[0] - mutex for manipulating with LeafVector
+ // mtx[1] - mutex for manipulating with tree
+ DepTree* leaf;
+ ObjectBase *ob,*eob;
+ bool err;
+ while(true)
+ {
+  // Begin locked section (errflag check, leafs manipulations)
+  mtx[0].lock();
+  // Is was error?
+  if(0!=errflag) {mtx[0].unlock(); return;}
+  // Is work finished?
+  if(0==root->childrens.size()) {mtx[0].unlock(); return;}
+  // Is jobs awaiting?
+  if(0==leafs->size()) {mtx[0].unlock(); std::this_thread::yield(); std::this_thread::sleep_for(std::chrono::milliseconds(100)); continue;}
+  // Select working node
+  leaf=*(leafs->begin());
+  // and remove its from list
+  leafs->erase(leafs->begin());
+  mtx[0].unlock();
+  // End locked section
+
+  if(DepTree::SAVE==leaf->type)
+  {
+   COUT(INFO)<<"save ("<<G_tosave[leaf->index]->Dump()<<")"<<std::endl;
+  }
+
+  if(DepTree::PRINT==leaf->type)
+  {
+   COUT(INFO)<<"print ("<<G_toprint[leaf->index]->Dump()<<")"<<std::endl;
+  }
+
+  if(DepTree::VAR==leaf->type)
+  {
+   err=false;
+   ob=G_vars.at(leaf->name);
+   // Main working call
+   eob=ob->Evaluate(&err);
+   if(err)
+   {
+    COUT(ERROR)<<" in definition of variable "<<leaf->name<<std::endl;
+    // Begin locked section (errflag set)
+    mtx[0].lock();
+    *errflag=1;
+    mtx[0].unlock();
+    // End locked section
+    return;
+   }
+
+   // eob is evaluated object
+   if(0!=eob) delete ob;
+   else eob=ob;
+   G_vars.erase(leaf->name); // Concurrent access is safe
+   // Begin locked section
+   mtx[1].lock();
+   for(auto& i:leaf->parents)
+   {
+    // leaf not children of anyone
+    i->childrens.erase(leaf);
+    // Replace variable on eob
+    if(DepTree::SAVE==i->type) G_tosave[i->index]->ReplaceVar(leaf->name,eob);   // ReplaceVar always return 0 for ObjectList
+    if(DepTree::PRINT==i->type) G_toprint[i->index]->ReplaceVar(leaf->name,eob);
+    if(DepTree::VAR==i->type)
+    {
+     ob=G_vars[i->name]->ReplaceVar(leaf->name,eob);
+     if(0!=ob) {delete G_vars[i->name]; G_vars[i->name]=ob;}
+    }
+    // If node have no children, it's a new leaf node
+    if(0==i->childrens.size() && DepTree::ROOT!=i->type) leafs->push_back(i);
+   }
+   mtx[1].unlock();
+   // End locked section
+   leaf->parents.clear();
+   delete leaf;
+  }
+ }
+}
+
+
+// Single-threaded version
+void TreeEvaluate(int* errflag, DepTree::LeafVector* leafs)
+{
+ DepTree* leaf;
+ ObjectBase *ob,*eob;
+ bool err;
+ while(0!=leafs->size())
+ {
+  // Select working node
+  leaf=*(leafs->begin());
+  // and remove its from list
+  leafs->erase(leafs->begin());
+
+  if(DepTree::SAVE==leaf->type)
+  {
+   COUT(INFO)<<"save ("<<G_tosave[leaf->index]->Dump()<<")"<<std::endl;
+  }
+
+  if(DepTree::PRINT==leaf->type)
+  {
+   COUT(INFO)<<"print ("<<G_toprint[leaf->index]->Dump()<<")"<<std::endl;
+  }
+
+  if(DepTree::VAR==leaf->type)
+  {
+   err=false;
+   ob=G_vars.at(leaf->name);
+   // Main working call
+   eob=ob->Evaluate(&err);
+   if(err)
+   {
+    COUT(ERROR)<<" in definition of variable "<<leaf->name<<std::endl;
+    *errflag=1;
+    return;
+   }
+
+   // eob is evaluated object
+   if(0!=eob) delete ob;
+   else eob=ob;
+   G_vars.erase(leaf->name); // Concurrent access is safe
+   for(auto& i:leaf->parents)
+   {
+    // leaf not children of anyone
+    i->childrens.erase(leaf);
+    // Replace variable on eob
+    if(DepTree::SAVE==i->type) G_tosave[i->index]->ReplaceVar(leaf->name,eob);   // ReplaceVar always return 0 for ObjectList
+    if(DepTree::PRINT==i->type) G_toprint[i->index]->ReplaceVar(leaf->name,eob);
+    if(DepTree::VAR==i->type)
+    {
+     ob=G_vars[i->name]->ReplaceVar(leaf->name,eob);
+     if(0!=ob) {delete G_vars[i->name]; G_vars[i->name]=ob;}
+    }
+    // If node have no children, it's a new leaf node
+    if(0==i->childrens.size() && DepTree::ROOT!=i->type) leafs->push_back(i);
+   }
+   leaf->parents.clear();
+   delete leaf;
+  }
+ }
+}
+
+
+int DepTree::EvaluateTree()
+{
+ int errflag=0;
+ LeafVector leafs=FindLeafNodes();
+
+ TreeEvaluate(&errflag,&leafs);
+ return errflag;
+}
diff --git a/src/deptree.h b/src/deptree.h
index 274b73b..a74e529 100644
--- a/src/deptree.h
+++ b/src/deptree.h
@@ -3,10 +3,13 @@
 #include <set>
 #include <vector>
 #include <string>
+#include <mutex>
+#include <thread>
 #include "globals.h"
 
 class DepTree
 {
+ typedef std::vector<DepTree*> LeafVector;
  enum NodeType {NOTDEF,ROOT,SAVE,PRINT,VAR};
 
  typedef std::set<DepTree*> NodeVector;
@@ -16,13 +19,15 @@ class DepTree
  NodeType type;
  G_toType::size_type index;
  std::string name;
+ mutable bool visited;
 
  int CreateNodeFromVar(const std::string& var, UsedType& used, CallStack& callstack);
  int CreateNodeFromSP(NodeType list, G_toType::size_type ind, UsedType& used);
  DepTree* FindNodeByVarFromCurrent(const std::string& var) const;
  DepTree* FindNodeByVar(const std::string& var) const;
+ LeafVector FindLeafNodes() const;
 public:
- DepTree():type(DepTree::NOTDEF) {}
+ DepTree():type(DepTree::NOTDEF),visited(false) {}
  DepTree(const DepTree&) = delete;
  ~DepTree()
  {
@@ -35,6 +40,9 @@ public:
  }
 
  int CreateGlobalTree(UsedType& used);
+ int EvaluateTree();
+ friend void TreeEvaluate(std::mutex* mtx, int* errflag, LeafVector* leafs, const DepTree* root);
+ friend void TreeEvaluate(int* errflag, LeafVector* leafs);
 };
 
 #endif
diff --git a/src/main.cpp b/src/main.cpp
index d7f0c60..1c28619 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -41,9 +41,9 @@ int main(int argc, char** argv)
  ret=CheckFunctions(); if(ret!=0) { ClearGlobals(); delete DPTree; return 1;}
  COUT(INFO)<<"Ok"<<std::endl;
 
- DumpConfig();
-
- COUT(INFO)<<sizeof(DepTree)<<" "<<sizeof(ObjectList)<<std::endl;
+ COUT(INFO)<<"Evaluate tree ";
+ ret=DPTree->EvaluateTree(); if(ret!=0) { ClearGlobals(); delete DPTree; return 1;}
+ COUT(INFO)<<"Ok"<<std::endl;
 
  ClearGlobals();
  delete DPTree;