爲什麼我在共享內存中編譯C代碼時遇到「未定義的引用'sem_init'」錯誤

Question

我是使用共享內存的初學者，並且實現了一個並行加法器，其中每個k處理器都在其中實現作爲一個孩子的過程。具體來說，給定一組n個整數和k的值，主程序創建k個子進程，爲每個子進程分配計算其分配給n/k個數的上限的總和，等待每個k的小計子流程，總計小計，並打印每個小計的結果以及總計。我沒有使用線程。

此程序是爲在大學任命而創建的，他們預計可在任何部門計算機上運行。

此代碼在Kali Linux上正確編譯，但無法在其他Linux版本上編譯和運行。 當我試圖在Ubuntu編譯它給出了錯誤說

未定義參考「sem_init」

我編制的線路使用-lrt。請幫我解決這個問題。

這是我創建的代碼。

#include<stdio.h> 
#include<sys/ipc.h> 
#include<sys/wait.h> 
#include<sys/stat.h> 
#include<sys/types.h> 
#include<fcntl.h> 
#include<errno.h> 
#include<semaphore.h> 
#include<unistd.h> 
#include<math.h> 
#include<stdlib.h> 

#define BUFFER_SIZE 100 
#define BUFFER_SUB 2 

typedef struct 
{ 
    int bufMax; 
    int datalimit; 
    int buff[BUFFER_SIZE]; 
    sem_t mutex, empty, full; 

} shared_inputs; 
typedef struct 
{ 
     int sub[BUFFER_SUB]; 
     sem_t mutex,empty,full; 
}sub_tot; 

int main(int argc, char *argv[]) 
{ 
    int x = 0; 
    int data,count,i,j,tot; 
    int n; 
    int k =atoi(argv[2]); 
    int assign_size; 
    count = tot =0; 




    int segment_id; 
     size_t segment_size = sizeof(shared_inputs); 
     segment_id = shmget(IPC_PRIVATE,segment_size,IPC_CREAT|0666); 
     shared_inputs *shared_memory = shmat(segment_id,NULL,0); 

    sem_init(&shared_memory->mutex,1,1); 
     sem_init(&shared_memory->empty,1,BUFFER_SIZE); 
     sem_init(&shared_memory->full,1,0); 



    int segment_idSubs; 
     size_t segment_size1 = sizeof(sub_tot); 
     segment_idSubs = shmget(IPC_PRIVATE,segment_size1,IPC_CREAT|0666); 
     sub_tot *subtotal = shmat(segment_idSubs,NULL,0); 

    sem_init(&subtotal->mutex,1,1); 
     sem_init(&subtotal->empty,1,BUFFER_SUB); 
     sem_init(&subtotal->full,1,0); 

    FILE *numFile; 
    numFile = fopen(argv[1], "r"); 



    while(!feof(numFile)) 
     { 
     fscanf(numFile,"%d",&data); 
       sem_wait(&shared_memory->empty); 
       sem_wait(&shared_memory->mutex); 
       shared_memory->buff[x] = data; 
       sem_post(&shared_memory->mutex); 
       sem_post(&shared_memory->full); 
     printf("%d ", shared_memory->buff[x]); 
       x++; 
     n = x; 

     } 
    assign_size = ceil((double)n/(double)k); 
    printf("\n"); 
    shared_memory->datalimit = 0; 
    shared_memory->bufMax = n-1; 
    printf("assigned size : %d \n", assign_size); 
    printf("n : %d , k : %d \n",n,k); 


    for(i =0; i < k; i++) 
    { 
     int id; 
     int subt = 0; 

     id = fork(); 
     if(id < 0) // error in fork 
     { 
      perror("Error in fork "); 
      exit(300); 
     } 
     else if(id == 0)//the new child process 
     { 


      for(j=0;j< assign_size; j++)//getting items from the shared memory 
      { 

       sem_wait(&shared_memory->full); 
           sem_wait(&shared_memory->mutex); 
           int num = shared_memory->buff[shared_memory->datalimit]; 
       //printf("%d \n",shared_memory->buff[shared_memory->datalimit]); 
       shared_memory->datalimit++; 
           sem_post(&shared_memory->mutex); 
           sem_post(&shared_memory->empty); 
           subt = subt + num; 
       if(shared_memory->datalimit == shared_memory->bufMax) 
       { 
        break; 
       } 

      } 

      int pid = getpid(); 
         sem_wait(&subtotal->empty); 
         sem_wait(&subtotal->mutex); 
         subtotal->sub[0] = pid; 
         subtotal->sub[1] = subt; 
         sem_post(&subtotal->mutex); 
         sem_post(&subtotal->full); 
      printf("Sub-total produced by Processor with ID %d: %d \n",pid,subt); 

      exit(0); 
     } 
     else//parent process 
     { 
      int status; 
         wait(&status); 
         sem_wait(&subtotal->full); 
         sem_wait(&subtotal->mutex); 
         int sub = subtotal->sub[1]; 
         sem_post(&subtotal->mutex); 
         sem_post(&subtotal->empty); 
         tot = tot+sub; 
     } 
    } 
    printf("Total: %d \n",tot); 


    return 0; 

} 

Answer 1

需要在編譯和使用-lm和-lrt時添加-lpthread。