diff --git a/src/engine_base.cc b/src/allreduce_base.cc
similarity index 99%
rename from src/engine_base.cc
rename to src/allreduce_base.cc
index 556b71e08..ca63f5c1c 100644
--- a/src/engine_base.cc
+++ b/src/allreduce_base.cc
@@ -1,5 +1,5 @@
 /*!
- * \file engine_base.cc
+ * \file allreduce_base.cc
  * \brief Basic implementation of AllReduce
  *
  * \author Tianqi Chen, Ignacio Cano, Tianyi Zhou
@@ -8,7 +8,7 @@
 #define _CRT_SECURE_NO_DEPRECATE
 #define NOMINMAX
 #include <cstring>
-#include "./engine_base.h"
+#include "./allreduce_base.h"
 
 namespace rabit {
 namespace engine {
diff --git a/src/engine_base.h b/src/allreduce_base.h
similarity index 98%
rename from src/engine_base.h
rename to src/allreduce_base.h
index 48d38aeb9..5ddf27635 100644
--- a/src/engine_base.h
+++ b/src/allreduce_base.h
@@ -1,5 +1,5 @@
 /*!
- * \file engine_base.h
+ * \file allreduce_base.h
  * \brief Basic implementation of AllReduce
  *   using TCP non-block socket and tree-shape reduction.
  *
@@ -8,8 +8,8 @@
  *
  * \author Tianqi Chen, Ignacio Cano, Tianyi Zhou
  */
-#ifndef RABIT_ENGINE_BASE_H
-#define RABIT_ENGINE_BASE_H
+#ifndef RABIT_ALLREDUCE_BASE_H
+#define RABIT_ALLREDUCE_BASE_H
 
 #include <vector>
 #include <string>
@@ -275,4 +275,4 @@ class AllReduceBase : public IEngine {
 };
 }  // namespace engine
 }  // namespace rabit
-#endif  // RABIT_ENGINE_BASE_H
+#endif  // RABIT_ALLREDUCE_BASE_H
diff --git a/src/engine_robust-inl.h b/src/allreduce_robust-inl.h
similarity index 99%
rename from src/engine_robust-inl.h
rename to src/allreduce_robust-inl.h
index 1eae685cc..cc9943282 100644
--- a/src/engine_robust-inl.h
+++ b/src/allreduce_robust-inl.h
@@ -1,5 +1,5 @@
 /*!
- * \file engine_robust-inl.h
+ * \file allreduce_robust-inl.h
  * \brief implementation of inline template function in AllReduceRobust
  *   
  * \author Tianqi Chen
diff --git a/src/engine_robust.cc b/src/allreduce_robust.cc
similarity index 99%
rename from src/engine_robust.cc
rename to src/allreduce_robust.cc
index 59a5b79a3..83b6a5fc8 100644
--- a/src/engine_robust.cc
+++ b/src/allreduce_robust.cc
@@ -1,5 +1,5 @@
 /*!
- * \file engine_robust.cc
+ * \file allreduce_robust.cc
  * \brief Robust implementation of AllReduce
  *
  * \author Tianqi Chen, Ignacio Cano, Tianyi Zhou
@@ -11,7 +11,7 @@
 #include <utility>
 #include "./io.h"
 #include "./utils.h"
-#include "./engine_robust.h"
+#include "./allreduce_robust.h"
 
 namespace rabit {
 namespace engine {
diff --git a/src/engine_robust.h b/src/allreduce_robust.h
similarity index 98%
rename from src/engine_robust.h
rename to src/allreduce_robust.h
index 32aee1f2b..d9eee6d25 100644
--- a/src/engine_robust.h
+++ b/src/allreduce_robust.h
@@ -1,5 +1,5 @@
 /*!
- * \file engine_robust.h
+ * \file allreduce_robust.h
  * \brief Robust implementation of AllReduce
  *   using TCP non-block socket and tree-shape reduction.
  *
@@ -7,11 +7,11 @@
  *   
  * \author Tianqi Chen, Ignacio Cano, Tianyi Zhou
  */
-#ifndef RABIT_ENGINE_ROBUST_H
-#define RABIT_ENGINE_ROBUST_H
+#ifndef RABIT_ALLREDUCE_ROBUST_H
+#define RABIT_ALLREDUCE_ROBUST_H
 #include <vector>
 #include "./engine.h"
-#include "./engine_base.h"
+#include "./allreduce_base.h"
 
 namespace rabit {
 namespace engine {
@@ -70,7 +70,7 @@ class AllReduceRobust : public AllReduceBase {
    *    this function is only used for test purpose
    */
   virtual void InitAfterException(void) {
-    this->CheckAndRecover(kGetExcept);
+    //this->CheckAndRecover(kGetExcept);
   }
 
  private:
@@ -371,6 +371,6 @@ class AllReduceRobust : public AllReduceBase {
 }  // namespace engine
 }  // namespace rabit
 // implementation of inline template function
-#include "./engine_robust-inl.h"
+#include "./allreduce_robust-inl.h"
 
-#endif // RABIT_ENGINE_ROBUST_H
+#endif // RABIT_ALLREDUCE_ROBUST_H
diff --git a/src/engine.cc b/src/engine.cc
index de58f4c4e..24ab1e588 100644
--- a/src/engine.cc
+++ b/src/engine.cc
@@ -10,8 +10,8 @@
 #define NOMINMAX
 
 #include "./engine.h"
-#include "./engine_base.h"
-#include "./engine_robust.h"
+#include "./allreduce_base.h"
+#include "./allreduce_robust.h"
 
 namespace rabit {
 namespace engine {
@@ -37,5 +37,14 @@ void Finalize(void) {
 IEngine *GetEngine(void) {
   return &manager;
 }
+// perform in-place allreduce, on sendrecvbuf 
+void AllReduce_(void *sendrecvbuf,
+                size_t type_nbytes,
+                size_t count,
+                IEngine::ReduceFunction red,               
+                mpi::DataType dtype,
+                mpi::OpType op) {
+  GetEngine()->AllReduce(sendrecvbuf, type_nbytes, count, red);
+}
 }  // namespace engine
 }  // namespace rabit
diff --git a/src/engine.h b/src/engine.h
index 1c040a9e4..873c02588 100644
--- a/src/engine.h
+++ b/src/engine.h
@@ -105,6 +105,37 @@ void Finalize(void);
 /*! \brief singleton method to get engine */
 IEngine *GetEngine(void);
 
+/*! \brief namespace that contains staffs to be compatible with MPI */
+namespace mpi {
+/*!\brief enum of all operators */
+enum OpType {
+  kMax, kMin, kSum, kBitwiseOR
+};
+/*!\brief enum of supported data types */
+enum DataType {
+  kInt,
+  kUInt,
+  kDouble,
+  kFloat
+};
+}  // namespace mpi
+/*!
+ * \brief perform in-place allreduce, on sendrecvbuf 
+ *   this is an internal function used by rabit to be able to compile with MPI
+ *   do not use this function directly
+ * \param sendrecvbuf buffer for both sending and recving data
+ * \param type_nbytes the unit number of bytes the type have
+ * \param count number of elements to be reduced
+ * \param reducer reduce function
+ * \param dtype the data type 
+ * \param op the reduce operator type
+ */
+void AllReduce_(void *sendrecvbuf,
+                size_t type_nbytes,
+                size_t count,
+                IEngine::ReduceFunction red,               
+                mpi::DataType dtype,
+                mpi::OpType op);
 }  // namespace engine
 }  // namespace rabit
 #endif  // RABIT_ENGINE_H
diff --git a/src/engine_mpi.cc b/src/engine_mpi.cc
new file mode 100644
index 000000000..c2e2a572d
--- /dev/null
+++ b/src/engine_mpi.cc
@@ -0,0 +1,115 @@
+/*!
+ * \file engine_mpi.cc
+ * \brief this file gives an implementation of engine interface using MPI,
+ *   this will allow rabit program to run with MPI, but do not comes with fault tolerant
+ *   
+ * \author Tianqi Chen
+ */
+#define _CRT_SECURE_NO_WARNINGS
+#define _CRT_SECURE_NO_DEPRECATE
+#define NOMINMAX
+#include "./engine.h"
+#include "./utils.h"
+#include <mpi.h>
+
+namespace rabit {
+namespace engine {
+/*! \brief implementation of engine using MPI */
+class MPIEngine : public IEngine {
+ public:
+  MPIEngine(void) {
+    version_number = 0;
+  }
+  virtual void AllReduce(void *sendrecvbuf_,
+                         size_t type_nbytes,
+                         size_t count,
+                         ReduceFunction reducer) {
+    utils::Error("MPIEngine:: AllReduce is not supported, use AllReduce_ instead");
+  }
+  virtual void Broadcast(void *sendrecvbuf_, size_t size, int root) {   
+    MPI::COMM_WORLD.Bcast(sendrecvbuf_, size, MPI::CHAR, root);
+  }
+  virtual void InitAfterException(void) {
+    utils::Error("MPI is not fault tolerant");
+  }
+  virtual int LoadCheckPoint(utils::ISerializable *p_model) {
+    return 0;
+  }
+  virtual void CheckPoint(const utils::ISerializable &model) {
+    version_number += 1;
+  }
+  virtual int VersionNumber(void) const {
+    return version_number;
+  }
+  /*! \brief get rank of current node */
+  virtual int GetRank(void) const {
+    return MPI::COMM_WORLD.Get_rank();    
+  }
+  /*! \brief get total number of */
+  virtual int GetWorldSize(void) const {
+    return MPI::COMM_WORLD.Get_size();    
+  }
+  /*! \brief get the host name of current node */  
+  virtual std::string GetHost(void) const {
+    int len;
+    char name[MPI_MAX_PROCESSOR_NAME];
+    MPI::Get_processor_name(name, len);
+    name[len] = '\0';
+    return std::string(name);
+  }
+
+ private:
+  int version_number;
+};
+
+// singleton sync manager
+MPIEngine manager;
+
+/*! \brief intiialize the synchronization module */
+void Init(int argc, char *argv[]) {
+  MPI::Init(argc, argv);
+}
+/*! \brief finalize syncrhonization module */
+void Finalize(void) {
+  MPI::Finalize();
+}
+
+/*! \brief singleton method to get engine */
+IEngine *GetEngine(void) {
+  return &manager;
+}
+// transform enum to MPI data type
+inline MPI::Datatype GetType(mpi::DataType dtype) {
+  using namespace mpi;
+  switch(dtype) {
+    case kInt: return MPI::INT;
+    case kUInt: return MPI::UNSIGNED;
+    case kFloat: return MPI::FLOAT;
+    case kDouble: return MPI::DOUBLE;
+  }
+  utils::Error("unknown mpi::DataType");
+  return MPI::CHAR;
+}
+// transform enum to MPI OP
+inline MPI::Op GetOp(mpi::OpType otype) {
+  using namespace mpi;
+  switch(otype) {
+    case kMax: return MPI::MAX;
+    case kMin: return MPI::MIN;
+    case kSum: return MPI::SUM;
+    case kBitwiseOR: return MPI::BOR;
+  }
+  utils::Error("unknown mpi::OpType");
+  return MPI::MAX;
+}
+// perform in-place allreduce, on sendrecvbuf 
+void AllReduce_(void *sendrecvbuf,
+                size_t type_nbytes,
+                size_t count,
+                IEngine::ReduceFunction red,               
+                mpi::DataType dtype,
+                mpi::OpType op) {  
+  MPI::COMM_WORLD.Allreduce(MPI_IN_PLACE, sendrecvbuf, count, GetType(dtype), GetOp(op));
+}
+}  // namespace engine
+}  // namespace rabit
diff --git a/src/rabit-inl.h b/src/rabit-inl.h
new file mode 100644
index 000000000..bc3c4a4fb
--- /dev/null
+++ b/src/rabit-inl.h
@@ -0,0 +1,123 @@
+/*!
+ * \file rabit-inl.h
+ * \brief implementation of inline template function for rabit interface
+ *   
+ * \author Tianqi Chen
+ */
+#ifndef RABIT_RABIT_INL_H
+#define RABIT_RABIT_INL_H
+
+namespace rabit {
+namespace engine {
+namespace mpi {
+// template function to translate type to enum indicator
+template<typename DType>
+inline DataType GetType(void);
+template<>
+inline DataType GetType<int>(void) {
+  return kInt;
+}
+template<>
+inline DataType GetType<unsigned>(void) {
+  return kUInt;
+}
+template<>
+inline DataType GetType<float>(void) {
+  return kFloat;
+}
+template<>
+inline DataType GetType<double>(void) {
+  return kDouble;
+}
+}  // namespace mpi
+}  // namespace engine
+
+namespace op {
+struct Max {
+  const static engine::mpi::OpType kType = engine::mpi::kMax;
+  template<typename DType>
+  inline static void Reduce(DType &dst, const DType &src) {
+    if (dst < src) dst = src;
+  }
+};
+struct Min {
+  const static engine::mpi::OpType kType = engine::mpi::kMin;
+  template<typename DType>
+  inline static void Reduce(DType &dst, const DType &src) {
+    if (dst > src) dst = src;
+  }
+};
+struct Sum {
+  const static engine::mpi::OpType kType = engine::mpi::kSum;
+  template<typename DType>
+  inline static void Reduce(DType &dst, const DType &src) {
+    dst += src;
+  }
+};
+struct BitOR {
+  const static engine::mpi::OpType kType = engine::mpi::kBitwiseOR;
+  template<typename DType>
+  inline static void Reduce(DType &dst, const DType &src) {
+    dst |= src;
+  }
+};
+template<typename OP, typename DType>
+inline void Reducer(const void *src_, void *dst_, int len, const MPI::Datatype &dtype) {
+  const DType *src = (const DType*)src_;
+  DType *dst = (DType*)dst_;  
+  for (int i = 0; i < len; ++i) {
+    OP::Reduce(dst[i], src[i]);
+  }
+}
+} // namespace op
+
+// intialize the rabit engine
+inline void Init(int argc, char *argv[]) {
+  engine::Init(argc, argv);
+}
+// finalize the rabit engine
+inline void Finalize(void) {
+  engine::Finalize();
+}
+// get the rank of current process
+inline int GetRank(void) {
+  return engine::GetEngine()->GetRank();
+}
+// the the size of the world
+inline int GetWorldSize(void) {
+  return engine::GetEngine()->GetWorldSize();
+}
+// get the name of current processor
+inline std::string GetProcessorName(void) {
+  return engine::GetEngine()->GetHost();
+}
+// broadcast an std::string to all others from root
+inline void Bcast(std::string *sendrecv_data, int root) {
+  engine::IEngine *e = engine::GetEngine();
+  unsigned len = static_cast<unsigned>(sendrecv_data->length());
+  e->Broadcast(&len, sizeof(len), root);
+  sendrecv_data->resize(len);
+  if (len != 0) {
+    e->Broadcast(&(*sendrecv_data)[0], len, root);  
+  }
+}
+// perform inplace AllReduce
+template<typename OP, typename DType>
+inline void AllReduce(DType *sendrecvbuf, size_t count) {
+  engine::AllReduce_(sendrecvbuf, sizeof(DType), count, op::Reducer<OP,DType>,
+                     engine::mpi::GetType<DType>(), OP::kType);
+}
+// load latest check point
+inline int LoadCheckPoint(utils::ISerializable *p_model) {
+  return engine::GetEngine()->LoadCheckPoint(p_model);
+}
+// checkpoint the model, meaning we finished a stage of execution
+inline void CheckPoint(const utils::ISerializable &model) {
+  engine::GetEngine()->CheckPoint(model);
+}
+// return the version number of currently stored model
+inline int VersionNumber(void) {
+  return engine::GetEngine()->VersionNumber();
+}
+}  // namespace rabit
+#endif
diff --git a/src/rabit.h b/src/rabit.h
index 5659798ec..0260ee52b 100644
--- a/src/rabit.h
+++ b/src/rabit.h
@@ -2,8 +2,9 @@
 #define RABIT_RABIT_H
 /*!
  * \file rabit.h
- * \brief This file defines a template wrapper of engine to give more flexible
- *      AllReduce operations
+ * \brief This file defines unified AllReduce/Broadcast interface of rabit
+ *   The actual implementation is redirected to rabit engine
+ *   Code only using this header can also compiled with MPI AllReduce(with no fault recovery),
  *
  * \author Tianqi Chen, Ignacio Cano, Tianyi Zhou
  */
@@ -13,53 +14,32 @@
 namespace rabit {
 /*! \brief namespace of operator */
 namespace op {
-struct Max {
-  template<typename DType>
-  inline static void Reduce(DType &dst, const DType &src) {
-    if (dst < src) dst = src;
-  }
-};
-struct Sum {
-  template<typename DType>
-  inline static void Reduce(DType &dst, const DType &src) {
-    dst += src;
-  }
-};
-struct BitOR {
-  template<typename DType>
-  inline static void Reduce(DType &dst, const DType &src) {
-    dst |= src;
-  }
-};
-template<typename OP, typename DType>
-inline void Reducer(const void *src_, void *dst_, int len, const MPI::Datatype &dtype) {
-  const DType *src = (const DType*)src_;
-  DType *dst = (DType*)dst_;  
-  for (int i = 0; i < len; ++i) {
-    OP::Reduce(dst[i], src[i]);
-  }
-}
+/*! \brief maximum value */
+struct Max;
+/*! \brief minimum value */
+struct Min;
+/*! \brief perform sum */
+struct Sum;
+/*! \brief perform bitwise OR */
+struct BitOR;
 }  // namespace op
 
-void Init(int argc, char *argv[]) {
-  engine::Init(argc, argv);
-}
-void Finalize(void) {
-  engine::Finalize();
-}
-
+/*!
+ * \brief intialize the rabit module, call this once function before using anything
+ * \param argc number of arguments in argv
+ * \param argv the array of input arguments
+ */
+inline void Init(int argc, char *argv[]);
+/*! 
+ * \brief finalize the rabit engine, call this function after you finished all jobs 
+ */
+inline void Finalize(void);
 /*! \brief get rank of current process */
-inline int GetRank(void) {
-  return engine::GetEngine()->GetRank();
-}
+inline int GetRank(void);
 /*! \brief get total number of process */
-int GetWorldSize(void) {
-  return engine::GetEngine()->GetWorldSize();
-}
+inline int GetWorldSize(void);
 /*! \brief get name of processor */
-std::string GetProcessorName(void) {
-  return engine::GetEngine()->GetHost();
-}
+inline std::string GetProcessorName(void);
 /*!
  * \brief broadcast an std::string to all others from root
  * \param sendrecv_data the pointer to send or recive buffer,
@@ -67,15 +47,7 @@ std::string GetProcessorName(void) {
  *                      and string will be resized to correct length
  * \param root the root of process
  */
-inline void Bcast(std::string *sendrecv_data, int root) {
-  engine::IEngine *e = engine::GetEngine();
-  unsigned len = static_cast<unsigned>(sendrecv_data->length());
-  e->Broadcast(&len, sizeof(len), root);
-  sendrecv_data->resize(len);
-  if (len != 0) {
-    e->Broadcast(&(*sendrecv_data)[0], len, root);  
-  }
-}
+inline void Bcast(std::string *sendrecv_data, int root);
 /*!
  * \brief perform in-place allreduce, on sendrecvbuf 
  *        this function is NOT thread-safe
@@ -90,9 +62,7 @@ inline void Bcast(std::string *sendrecv_data, int root) {
  * \tparam DType type of data
  */
 template<typename OP, typename DType>
-inline void AllReduce(DType *sendrecvbuf, size_t count) {
-  engine::GetEngine()->AllReduce(sendrecvbuf, sizeof(DType), count, op::Reducer<OP,DType>);
-}
+inline void AllReduce(DType *sendrecvbuf, size_t count);
 /*!
  * \brief load latest check point
  * \param p_model pointer to the model
@@ -110,9 +80,7 @@ inline void AllReduce(DType *sendrecvbuf, size_t count) {
  *
  * \sa CheckPoint, VersionNumber
  */
-inline int LoadCheckPoint(utils::ISerializable *p_model) {
-  return engine::GetEngine()->LoadCheckPoint(p_model);
-}
+inline int LoadCheckPoint(utils::ISerializable *p_model);
 /*!
  * \brief checkpoint the model, meaning we finished a stage of execution
  *  every time we call check point, there is a version number which will increase by one
@@ -120,16 +88,14 @@ inline int LoadCheckPoint(utils::ISerializable *p_model) {
  * \param p_model pointer to the model
  * \sa LoadCheckPoint, VersionNumber
  */
-inline void CheckPoint(const utils::ISerializable &model) {
-  engine::GetEngine()->CheckPoint(model);
-}
+inline void CheckPoint(const utils::ISerializable &model);
 /*!
  * \return version number of current stored model,
  *         which means how many calls to CheckPoint we made so far
  * \sa LoadCheckPoint, CheckPoint
  */
-inline int VersionNumber(void) {
-  return engine::GetEngine()->VersionNumber();
-}
+inline int VersionNumber(void);
 }  // namespace rabit
+// implementation of template functions
+#include "./rabit-inl.h"
 #endif  // RABIT_ALLREDUCE_H
diff --git a/test/.gitignore b/test/.gitignore
new file mode 100644
index 000000000..851969b1e
--- /dev/null
+++ b/test/.gitignore
@@ -0,0 +1,2 @@
+*.mpi
+test_*
diff --git a/test/Makefile b/test/Makefile
index a48fcd77c..bd14fff97 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -4,26 +4,31 @@ export MPICXX = mpicxx
 export LDFLAGS= -pthread -lm 
 export CFLAGS = -Wall -O3 -msse2  -Wno-unknown-pragmas -fPIC -I../src
 
-ifeq ($(no_omp),1)
-	CFLAGS += -DDISABLE_OPENMP 
-else 
-	CFLAGS += -fopenmp
-endif
-
 # specify tensor path
 BIN = test_allreduce test_recover test_model_recover
-OBJ = engine_base.o engine_robust.o engine.o
+# objectives that makes up rabit library
+RABIT_OBJ = allreduce_base.o allreduce_robust.o engine.o
+MPIOBJ = engine_mpi.o
+
+OBJ = $(RABIT_OBJ) test_allreduce.o test_recover.o test_model_recover.o
+MPIBIN = test_allreduce.mpi
 .PHONY: clean all
 
 all: $(BIN) $(MPIBIN)
 
-engine_tcp.o: ../src/engine_tcp.cpp ../src/*.h
-engine_base.o: ../src/engine_base.cc ../src/*.h
+allreduce_base.o: ../src/allreduce_base.cc ../src/*.h
 engine.o: ../src/engine.cc ../src/*.h
-engine_robust.o: ../src/engine_robust.cc ../src/*.h
-test_allreduce: test_allreduce.cpp ../src/*.h $(OBJ)
-test_recover: test_recover.cpp ../src/*.h $(OBJ)
-test_model_recover: test_model_recover.cpp ../src/*.h $(OBJ)
+allreduce_robust.o: ../src/allreduce_robust.cc ../src/*.h
+engine_mpi.o: ../src/engine_mpi.cc
+test_allreduce.o: test_allreduce.cpp ../src/*.h
+test_recover.o: test_recover.cpp ../src/*.h 
+test_model_recover.o: test_model_recover.cpp ../src/*.h
+
+# we can link against MPI version to get use MPI
+test_allreduce: test_allreduce.o  $(RABIT_OBJ)
+test_allreduce.mpi: test_allreduce.o $(MPIOBJ)
+test_recover: test_recover.o  $(RABIT_OBJ)
+test_model_recover: test_model_recover.o  $(RABIT_OBJ)
 
 $(BIN) : 
 	$(CXX) $(CFLAGS) $(LDFLAGS) -o $@ $(filter %.cpp %.o %.c %.cc, $^)
@@ -32,7 +37,10 @@ $(OBJ) :
 	$(CXX) -c $(CFLAGS) -o $@ $(firstword $(filter %.cpp %.c %.cc, $^) )
 
 $(MPIBIN) : 
-	$(MPICXX) $(CFLAGS) $(LDFLAGS) -o $@ $(filter %.cpp %.o %.c %.cc, $^)
+	$(MPICXX) $(CFLAGS)  $(LDFLAGS) -o $@ $(filter %.cpp %.o %.c %.cc, $^)
+
+$(MPIOBJ) : 
+	$(MPICXX) -c $(CFLAGS) -o $@ $(firstword $(filter %.cpp %.c %.cc, $^) )
 
 clean:
 	$(RM) $(OBJ) $(BIN) $(MPIBIN) *~ ../src/*~
diff --git a/test/test_allreduce.cpp b/test/test_allreduce.cpp
index 7f9ad9f78..e0fc9843f 100644
--- a/test/test_allreduce.cpp
+++ b/test/test_allreduce.cpp
@@ -79,7 +79,8 @@ int main(int argc, char *argv[]) {
   utils::LogPrintf("[%d] !!!TestMax pass\n", rank);
   TestSum(mock, n);
   utils::LogPrintf("[%d] !!!TestSum pass\n", rank);
-  for (int i = 0; i < nproc; i += nproc / 3) {
+  int step = std::max(nproc / 3, 1);
+  for (int i = 0; i < nproc; i += step) {
     TestBcast(mock, n, i);
   }
   utils::LogPrintf("[%d] !!!TestBcast pass\n", rank);
diff --git a/test/test_model_recover.cpp b/test/test_model_recover.cpp
index a7f4d7677..c6d2973ce 100644
--- a/test/test_model_recover.cpp
+++ b/test/test_model_recover.cpp
@@ -132,7 +132,7 @@ int main(int argc, char *argv[]) {
       }
       break;
     } catch (MockException &e) {
-      //rabit::engine::GetEngine()->InitAfterException();
+      rabit::engine::GetEngine()->InitAfterException();
       ++ntrial;
     }
   }
diff --git a/test/test_recover.cpp b/test/test_recover.cpp
index 761226889..9dfc7f60a 100644
--- a/test/test_recover.cpp
+++ b/test/test_recover.cpp
@@ -115,7 +115,7 @@ int main(int argc, char *argv[]) {
       // reach here
       break;
     } catch (MockException &e) {
-      //rabit::engine::GetEngine()->InitAfterException();
+      rabit::engine::GetEngine()->InitAfterException();
       ++ntrial;
     }
   }