diff --git a/src/Makefile b/src/Makefile
index 71f166c..d2a23ad 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,5 +1,5 @@
-CFLAGS=-O2 -g -std=gnu++11 -fvisibility=hidden -fpic -Wall
-LDFLAGS=-fvisibility=hidden -Wl,--export-dynamic -fpic -Wall
+CFLAGS=-O2 -g -std=gnu++11 -fvisibility=hidden -fpic -pthread -Wall
+LDFLAGS=-fvisibility=hidden -Wl,--export-dynamic -fpic -pthread -Wall
 
 CC=g++
 
diff --git a/src/deptree.cpp b/src/deptree.cpp
index f37b825..b9dc9c1 100644
--- a/src/deptree.cpp
+++ b/src/deptree.cpp
@@ -169,132 +169,190 @@ DepTree::LeafVector DepTree::FindLeafNodes() const
 
 
 // Multi-threaded version
-void TreeEvaluate(std::mutex* mtx, int* errflag, DepTree::LeafVector* leafs, const DepTree* root)
+void* TreeEvaluateM(void* arg)
 {
- // mtx[0] - mutex for manipulating with LeafVector
- // mtx[1] - mutex for manipulating with tree
+ struct timespec skip={0,10000000};
+ DepTree::thread_params* p=reinterpret_cast<DepTree::thread_params*>(arg);
  DepTree* leaf;
  ObjectBase *ob,*eob;
  ObjectList* ol;
  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;}
+  // Begin critical section (access to root)
+  pthread_mutex_lock(&p->root_mtx);
+  // Check, if all done, or error happens?
+  if(0==p->root->childrens.size() || 0!=p->exitcode) {pthread_mutex_unlock(&p->root_mtx); return 0;}
+  // End critical section
+  pthread_mutex_unlock(&p->root_mtx);
+
+  // Begin critical section (access to leafs)
+  pthread_mutex_lock(&p->leaf_mtx);
+  // Check, if some work available?
+  if(0==p->leafs.size()) {pthread_mutex_unlock(&p->leaf_mtx); nanosleep(&skip,0); continue;}
   // Select working node
-  leaf=*(leafs->begin());
+  leaf=*(p->leafs.begin());
   // and remove its from list
-  leafs->erase(leafs->begin());
-  mtx[0].unlock();
-  // End locked section
+  p->leafs.erase(p->leafs.begin());
+  // End critical section
+  pthread_mutex_unlock(&p->leaf_mtx);
 
   if(DepTree::SAVE==leaf->type)
   {
    err=false;
+
+   // Begin critical section (access to G_toprint or G_tosave)
+   pthread_mutex_lock(&p->prsv_mtx);
    ol=G_tosave[leaf->index];
+   // End critical section
+   pthread_mutex_unlock(&p->prsv_mtx);
+
    ol->Evaluate(&err); // For list Evaluate always return 0;
    if(err)
    {
     COUT(ERROR)<<" in instruction save"<<ol->Dump()<<")"<<std::endl;
-    *errflag=1;
-    return;
+    p->exitcode=1;
+    return 0;
    }
    if(!Save(ol))
    {
-    mtx[0].lock();
-    *errflag=1;
-    mtx[0].unlock();
-    return;
+    p->exitcode=1;
+    return 0;
    }
+   // This leaf can have only one parent - root
+   // Begin critical section (access to root)
+   pthread_mutex_lock(&p->root_mtx);
+   (*leaf->parents.begin())->childrens.erase(leaf);
+   // End critical section
+   pthread_mutex_unlock(&p->root_mtx);
   }
 
   if(DepTree::PRINT==leaf->type)
   {
    err=false;
+
+   // Begin critical section (access to G_toprint or G_tosave)
+   pthread_mutex_lock(&p->prsv_mtx);
    ol=G_toprint[leaf->index];
+   // End critical section
+   pthread_mutex_unlock(&p->prsv_mtx);
+
    ol->Evaluate(&err); // For list Evaluate always return 0;
    if(err)
    {
     COUT(ERROR)<<" in instruction print"<<ol->Dump()<<")"<<std::endl;
-    *errflag=1;
-    return;
+    p->exitcode=1;
+    return 0;
    }
    if(!Print(ol))
    {
-    mtx[0].lock();
-    *errflag=1;
-    mtx[0].unlock();
-    return;
+    p->exitcode=1;
+    return 0;
    }
+
+   // Begin critical section (access to root)
+   pthread_mutex_lock(&p->root_mtx);
+   // This leaf can have only one parent - root
+   (*leaf->parents.begin())->childrens.erase(leaf);
+   // End critical section
+   pthread_mutex_unlock(&p->root_mtx);
+
   }
 
   if(DepTree::VAR==leaf->type)
   {
-   err=false;
+   // Begin critical section (access to G_vars)
+   pthread_mutex_lock(&p->vars_mtx);
    ob=G_vars.at(leaf->name);
+   G_vars.erase(leaf->name);
+   // End critical section
+   pthread_mutex_unlock(&p->vars_mtx);
+
    // Main working call
+   err=false;
    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;
+    p->exitcode=1;
+    return 0;
    }
 
    // 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();
+
+   // Begin critical section (access to tree structure)
+   pthread_mutex_lock(&p->tree_mtx);
    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::SAVE==i->type)
+    {
+     // Begin critical section (access to G_toprint or G_tosave)
+     pthread_mutex_lock(&p->prsv_mtx);
+     G_tosave[i->index]->ReplaceVar(leaf->name,eob);    // ReplaceVar always return 0 for ObjectList
+     // End critical section
+     pthread_mutex_unlock(&p->prsv_mtx);
+    }
+    if(DepTree::PRINT==i->type)
+    {
+     // Begin critical section (access to G_toprint or G_tosave)
+     pthread_mutex_lock(&p->prsv_mtx);
+     G_toprint[i->index]->ReplaceVar(leaf->name,eob);   // ReplaceVar always return 0 for ObjectList
+     // End critical section
+     pthread_mutex_unlock(&p->prsv_mtx);
+    }
     if(DepTree::VAR==i->type)
     {
+     // Begin critical section (access to G_vars)
+     pthread_mutex_lock(&p->vars_mtx);
      ob=G_vars[i->name]->ReplaceVar(leaf->name,eob);
-     if(0!=ob) {delete G_vars[i->name]; G_vars[i->name]=ob;}
+     if(0!=ob)
+     {
+      delete G_vars[i->name];
+      G_vars[i->name]=ob;
+     }
+     // End critical section
+     pthread_mutex_unlock(&p->vars_mtx);
     }
+
+    // Begin critical section (access to leafs)
+    pthread_mutex_lock(&p->leaf_mtx);
     // If node have no children, it's a new leaf node
-    if(0==i->childrens.size() && DepTree::ROOT!=i->type) leafs->push_back(i);
+    if(0==i->childrens.size() && DepTree::ROOT!=i->type) p->leafs.push_back(i);
+    pthread_mutex_unlock(&p->leaf_mtx);
+    // End critical section
    }
-   mtx[1].unlock();
-   // End locked section
+   // End critical section
+   pthread_mutex_unlock(&p->tree_mtx);
    delete eob;
-   leaf->parents.clear();
-   delete leaf;
   }
+
+  leaf->parents.clear();
+  delete leaf;
  }
+ return 0;
 }
 
 
 // Single-threaded version
-void TreeEvaluate(int* errflag, DepTree::LeafVector* leafs)
+void* TreeEvaluate(void* arg)
 {
+ DepTree::thread_params* p=reinterpret_cast<DepTree::thread_params*>(arg);
  DepTree* leaf;
  ObjectBase *ob,*eob;
  ObjectList* ol;
  bool err;
- while(0!=leafs->size())
+ while(0!=p->leafs.size())
  {
   // Select working node
-  leaf=*(leafs->begin());
+  leaf=*(p->leafs.begin());
   // and remove its from list
-  leafs->erase(leafs->begin());
+  p->leafs.erase(p->leafs.begin());
 
   if(DepTree::SAVE==leaf->type)
   {
@@ -304,15 +362,17 @@ void TreeEvaluate(int* errflag, DepTree::LeafVector* leafs)
    if(err)
    {
     COUT(ERROR)<<" in instruction save"<<ol->Dump()<<")"<<std::endl;
-    *errflag=1;
-    return;
+    p->exitcode=1;
+    return 0;
    }
    // eob is evaluated object
    if(!Save(ol))
    {
-    *errflag=1;
-    return;
+    p->exitcode=1;
+    return 0;
    }
+   // This leaf can have only one parent - root
+   (*leaf->parents.begin())->childrens.erase(leaf);
   }
 
   if(DepTree::PRINT==leaf->type)
@@ -323,33 +383,36 @@ void TreeEvaluate(int* errflag, DepTree::LeafVector* leafs)
    if(err)
    {
     COUT(ERROR)<<" in instruction print"<<ol->Dump()<<")"<<std::endl;
-    *errflag=1;
-    return;
+    p->exitcode=1;
+    return 0;
    }
    if(!Print(ol))
    {
-    *errflag=1;
-    return;
+    p->exitcode=1;
+    return 0;
    }
+   // This leaf can have only one parent - root
+   (*leaf->parents.begin())->childrens.erase(leaf);
   }
 
   if(DepTree::VAR==leaf->type)
   {
    err=false;
    ob=G_vars.at(leaf->name);
+   G_vars.erase(leaf->name);
    // Main working call
    eob=ob->Evaluate(&err);
    if(err)
    {
     COUT(ERROR)<<" in definition of variable "<<leaf->name<<std::endl;
-    *errflag=1;
-    return;
+    p->exitcode=1;
+    return 0;
    }
 
    // eob is evaluated object
    if(0!=eob) delete ob;
    else eob=ob;
-   G_vars.erase(leaf->name);
+   //G_vars.erase(leaf->name);
    for(auto& i:leaf->parents)
    {
     // leaf not children of anyone
@@ -363,21 +426,45 @@ void TreeEvaluate(int* errflag, DepTree::LeafVector* leafs)
      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);
+    if(0==i->childrens.size() && DepTree::ROOT!=i->type) p->leafs.push_back(i);
    }
    delete eob;
-   leaf->parents.clear();
-   delete leaf;
   }
+  leaf->parents.clear();
+  delete leaf;
  }
+ return 0;
 }
 
 
-int DepTree::EvaluateTree()
+int DepTree::EvaluateTree(unsigned int nthreads)
 {
- int errflag=0;
- LeafVector leafs=FindLeafNodes();
+ DepTree::thread_params p;
 
- TreeEvaluate(&errflag,&leafs);
- return errflag;
+ p.exitcode=0;
+ p.leafs=FindLeafNodes();
+
+ if(1==nthreads) TreeEvaluate(&p);
+ else
+ {
+  pthread_t* threads=new pthread_t[nthreads-1];
+  p.root=this;
+  pthread_mutex_init(&p.leaf_mtx,0);
+  pthread_mutex_init(&p.root_mtx,0);
+  pthread_mutex_init(&p.vars_mtx,0);
+  pthread_mutex_init(&p.prsv_mtx,0);
+  pthread_mutex_init(&p.tree_mtx,0);
+  while(0!=p.root->parents.size()) p.root=*(p.root->parents.begin());
+
+  for(unsigned int i=0;i<nthreads-1;++i) pthread_create(threads+i,0,&TreeEvaluateM,&p);
+  TreeEvaluateM(&p);
+  for(unsigned int i=0;i<nthreads-1;++i) pthread_join(threads[i],0);
+  delete[] threads;
+  pthread_mutex_destroy(&p.leaf_mtx);
+  pthread_mutex_destroy(&p.root_mtx);
+  pthread_mutex_destroy(&p.vars_mtx);
+  pthread_mutex_destroy(&p.prsv_mtx);
+  pthread_mutex_destroy(&p.tree_mtx);
+ }
+ return p.exitcode;
 }
diff --git a/src/deptree.h b/src/deptree.h
index 2928c1e..50107f1 100644
--- a/src/deptree.h
+++ b/src/deptree.h
@@ -3,18 +3,30 @@
 #include <set>
 #include <vector>
 #include <string>
-#include <mutex>
-#include <thread>
+#include <pthread.h>
+#include <time.h>
 #include "globals.h"
 
 class DepTree
 {
  typedef std::vector<DepTree*> LeafVector;
  typedef std::map<std::string,DepTree*> DepTreeVars;
- enum NodeType {NOTDEF,ROOT,SAVE,PRINT,VAR};
-
  typedef std::set<DepTree*> NodeVector;
  typedef std::set<DepTree*> CallStack;
+ enum NodeType {NOTDEF,ROOT,SAVE,PRINT,VAR};
+
+ typedef struct
+ {
+  const DepTree* root;
+  int exitcode;
+  LeafVector leafs;
+  pthread_mutex_t leaf_mtx;
+  pthread_mutex_t root_mtx;
+  pthread_mutex_t vars_mtx;
+  pthread_mutex_t prsv_mtx;
+  pthread_mutex_t tree_mtx;
+ } thread_params;
+
  NodeVector parents;
  NodeVector childrens;
  NodeType type;
@@ -39,9 +51,9 @@ 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);
+ int EvaluateTree(unsigned int nthreads);
+ friend void* TreeEvaluateM(void* arg);
+ friend void* TreeEvaluate (void* arg);
 };
 
 #endif
diff --git a/src/main.cpp b/src/main.cpp
index 77124ec..0987e95 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -68,7 +68,7 @@ int main(int argc, char** argv)
  else
  {
   COUT(INFO)<<"Evaluate tree ";
-  ret=DPTree->EvaluateTree(); if(ret!=0) { ClearGlobals(); delete DPTree; return 1;}
+  ret=DPTree->EvaluateTree(options.threads); if(ret!=0) { ClearGlobals(); delete DPTree; return 1;}
   COUT(INFO)<<"Ok"<<std::endl;
  }