[并行与分布式程序设计] Xcode上MPI编程环境搭建 & Hello World实现

1. Running Open MPI on macOS

2. brew install mpich

3. Xcode设置条件编译参数

4. Debugging and Running MPI in Xcode. 注意其中的工程设置!! 很有用

   #include <iostream>
   #include <mpi.h>
   
   // C
   //int main(int argc, char * argv[]){
   //    int my_id, num_procs;
   //    int name_len;
   //    char processer_name[MPI_MAX_PROCESSOR_NAME];
   //    MPI_Init(&argc, &argv);
   //    MPI_Comm_rank(MPI_COMM_WORLD, &my_id);
   //    MPI_Comm_size(MPI_COMM_WORLD, &num_procs);
   //    MPI_Get_processor_name(processer_name, &name_len);
   //    printf("hello world! Process %d of %d on %s\n", my_id, num_procs, processer_name);
   //
   //    MPI_Finalize();
   //}
   
   // C++
   int main(int argc, char * argv[]) {
       int rank, size, name_len;
       char processer_name[MPI_MAX_PROCESSOR_NAME];
       MPI::Init(argc, argv);
       rank = MPI::COMM_WORLD.Get_rank();
       size = MPI::COMM_WORLD.Get_size();
       // 和C语言不同, 第二个参数C中是指针, C++中是引用
       MPI::Get_processor_name(processer_name, name_len);
       
       std::cout<<"Greetings from process "<<rank<<" of "<<size<<" on "<<processer_name<<"\n";
       MPI::Finalize();
       return 0;
   }
   

5. Mac OS X下利用MPI进行并行计算

6. Xcode中使用MPIRUN运行, 需要把MPI件夹中的那个二进制运行文件复制一下(mpiruncopy)才能被选中

7. MPI_Send 和 MPI_Recv 的使用, ANY_TAG, ANY_SORCE

   #include <stdio.h>
   #include <mpi.h>
   
   // C
   int main(int argc, char * argv[]){
       int my_id;
       int name_len;
       char message[20];
       MPI_Status status;
       char processer_name[MPI_MAX_PROCESSOR_NAME];
       MPI_Init(&argc, &argv);
       MPI_Comm_rank(MPI_COMM_WORLD, &my_id);
       MPI_Get_processor_name(processer_name, &name_len);
       if (my_id == 0) {
           strcpy(message, "Hello Process 1");
           printf("Process 0 on %s send %s\n", processer_name, message);
           MPI_Send(message, 20, MPI_CHAR, 1, 99, MPI_COMM_WORLD);
       }
       else if (my_id == 1) {
           MPI_Recv(message, 20, MPI_CHAR, 0, 99, MPI_COMM_WORLD, &status);
           printf("Process 1 on %s received %s\n", processer_name, message);
       }
       MPI_Finalize();
       return 0;
   }
   

   #include <stdio.h>
   #include <mpi.h>
   
   int main(int argc, char * argv[]){
       int rank, size, buf[1];
       MPI_Status status;
       MPI_Init(&argc, &argv);
       MPI_Comm_rank(MPI_COMM_WORLD, &rank);
       MPI_Comm_size(MPI_COMM_WORLD, &size);
       if (rank == 0) {
           for (int i = 0; i < (size - 1); i++) {
               MPI_Recv(buf, 1, MPI_INT, MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status);
               printf("Msg=%d from %d with tag %d\n", buf[0], status.MPI_SOURCE, status.MPI_TAG);
           }
       }
       else {
           buf[0] = rank;
           MPI_Send(buf, 1, MPI_INT, 0, 100-rank, MPI_COMM_WORLD);
       }
       MPI_Finalize();
       return 0;
   }