Question

我正在尝试使用线程实现内存和不同的分页算法。现在当我运行我的代码时，只运行前两个线程，而不是第三个。这是它打印的内容：

Thread one: Task 1, Sequence 1
Thread two: Task 1, Sequence 2

如果有人能告诉我为什么我的第三个线程没有运行，那将非常有帮助。

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>

pthread_mutex_t MemoryLock;
int k = 10;
int m = 10;
int n = 1000;
int seq = 0;
int start = 0; //for thread 2
int end = 10; //end is equal to value of k for thread 2

int disk[1000];

int MemoryLookupTable[10]; //Stores which variable is present in memory
int PhysicalMemory[10]; //Stores the value of the variables
int MetaTable[10]; //Meta level information

void least_recent(int i){
    int t, position, smallest, disk_num;

    t = 1;
    smallest = MetaTable[0];
    position = 0;

    while(t < m){
        if(smallest > MetaTable[t]){
            smallest = MetaTable[t];
            position = t;
        }
        t++;
    }

    disk_num = MemoryLookupTable[position];
    disk[disk_num] = PhysicalMemory[position];

    PhysicalMemory[position] = disk[i];
    MemoryLookupTable[position] = i;
    MetaTable[position] = seq;
}

void most_recent(int i){
    int t, position, largest, disk_num;

    t = 1;
    largest = MetaTable[0];
    position = 0;

    while(t < m){
        if(largest < MetaTable[t]){
            largest = MetaTable[t];
            position = t;
        }
        t++;
    }

    disk_num = MemoryLookupTable[position];
    disk[disk_num] = PhysicalMemory[position];

    PhysicalMemory[position] = disk[i];
    MemoryLookupTable[position] = i;
    MetaTable[position] = seq;
}

void random_order(int i){
    int r, disk_num;
    r = m * (rand() / (RAND_MAX + 1.0));

    disk_num = MemoryLookupTable[r];
    disk[disk_num] = PhysicalMemory[r];

    PhysicalMemory[r] = disk[i];
    MemoryLookupTable[r] = i;
}

int fetch(int i){
    int x = 0;
    int x_i;

    x_i = disk[i];
    while(x < m){
        if(x_i == PhysicalMemory[x])
            return x_i;
        x++;
    }

    return -1;
}

void PageIn(int i){
    int x = 0;
    int present;

    present = fetch(i);
    if(present == -1)
        return; //Do not need to page in, since variable is already there.

    least_recent(i);
    //most_recent(i); I am testing each algorithm at a time, so these are commented out.
    //random_order(i);
}

void *t1(){
    int sum, task, r, i, fetched;
    sum, task = 0;
    r = rand() % (n - k) + k;

    for(i = 0; i < k - 1; i++){
        pthread_mutex_lock(&MemoryLock);
        seq++;
        fetched = fetch(i);
        if(fetched == -1){
            PageIn(i);
            pthread_mutex_unlock(&MemoryLock);
            if(i = (k - 2))
           break;
        }
        sum = sum + disk[i];
        pthread_mutex_unlock(&MemoryLock);
   }

   sum = sum + disk[r];
   task++;
   printf("\nThread one: Task %d, Sequence %d", task, seq);

   return NULL;
}

void *t2(){
    int sum, task, i, fetched;
    sum, task = 0;

    for(i = start; i < end; i++){
        pthread_mutex_lock(&MemoryLock);
        seq++;
        fetched = fetch(i);
        if(fetched == -1){
            PageIn(i);
            pthread_mutex_unlock(&MemoryLock);
            if(i = (end - 1)){
          sum = sum + disk[i];
          break;
            }
        }
        sum = sum + disk[i];
        pthread_mutex_unlock(&MemoryLock);
    }

    sum = sum + disk[i];
    task++;
    start++;
    if(end == n){
        start = 0;
        end = k;
    }
    else
        end++;
    printf("\nThread two: Task %d, Sequence %d", task, seq);

    return NULL;
}

void *t3(){
    int sum, task, r, i, fetched;

    for(i = 0; i < k; i++){
        pthread_mutex_lock(&MemoryLock);
        seq++;
        r =  n * (rand() / (RAND_MAX + 1.0));
        fetched = fetch(r);
        if(fetched == -1){
            PageIn(r);
            pthread_mutex_unlock(&MemoryLock);
            if(i = (k - 1)){
          sum = sum + disk[r];
          break;
            }
        }
        sum = sum + disk[r];
        pthread_mutex_unlock(&MemoryLock);
   }

   sum = sum + disk[r];
   task++;
   printf("\nThread three: Task %d, Sequence %d", task, seq);

   return NULL;
}

main(){
    int pt1, pt2, pt3, i, j, randNum;
    pthread_t thread1, thread2, thread3;

    for(i = 0; i < n; i++){
        randNum = 200 * (rand() / (RAND_MAX + 1.0));
        disk[i] = randNum;
    }

    for(j = 0; j < m; j++) //initializing array to empty
        MemoryLookupTable[j] = -1;

    if((pt1 = pthread_create(&thread1, NULL, t1, NULL)))
         printf("Thread creation failed: %d\n", pt1);

    if((pt2 = pthread_create(&thread2, NULL, t2, NULL)))
         printf("Thread creation failed: %d\n", pt2);

    if((pt3 = pthread_create(&thread3, NULL, t3, NULL)))
         printf("Thread creation failed: %d\n", pt3);

    pthread_join(thread1, NULL);
    pthread_join(thread2, NULL); 
    pthread_join(thread3, NULL);  

    pthread_exit(0); 
}

Answer 1

我运行你的程序，第三个线程成功执行。尝试将"\n"添加到t3()输出的末尾：

printf("\nThread three: Task %d, Sequence %d\n", task, seq);

如果行尾没有换行符，则终端可能无法显示。

我的C程序出了什么问题

1 个答案: