Starvation Solution for Reader Writer Problem using Semaphore

Starvation Solution for Reader Writer Problem using Semaphore

05:30

Description: The solution of the Readers-Writers problem usually given may starve the writers. So, following is a starvation-free solution for Reader Writer problem using semaphore.

semaphore rw_mutex=1;

semaphore mutex=1;

semaphore turn=1;     //new added line

int read_count=0;

//Writer Process

do{

   wait(turn);        //new added line

   wait(rw_mutex);

   signal(turn);      //new added line

  

   /* Writing is Performed */

  

   signal(rw_mutex);

}while(true);

//Reader Process

do{

   wait(turn);        //new added line

   wait(mutex);

  

   read_count++;

   if(read_count==1)

      wait(rw_mutex);

   signal(turn);      //new added line

  

   signal(mutex);

  

   /* Reading is Performed */

  

   wait(mutex);

  

   read_count--;

   if(read_count==0)

      signal(rw_mutex);

  

   signal(mutex);

}while(true);