c - 多线程程序C中的段错误

标签 c linux multithreading segmentation-fault pthreads

我制作了以下程序作为我的学术项目的一部分。因为我无法确定实际问题，所以我给出了整个程序。

#include<stdio.h>
#include<math.h>
#include<pthread.h>
//Structure for getting dam details
struct dam
{
    float max_height;
    float min_height;
    float sto_capacity;
    float pro_capacity;
    float stn_const;
    float crnt_lvl;
    float delay;
    float crnt_lvl_min;
    float crnt_lvl_max;
    float unit_vol;
    float water_req;
    float work_hr;
    int work_hr_int;
};
//global variables
int n, i, extra_w_hr_int, extra_w_hr_ref, j, k, flag, l, m, swap, pos=11, h, main_flag=1, days_count=0, temp_extra_w_hr_ref;
int jj, k1, flag1, l1, m1, swap1, g=0;
float extra_w_hr, extra_height, diff_level, extra_water;
int rank[24];
int rank1[24];
float rate[24];
float water_pu[24];
float sum_rate1[24];
float avg_rate1[24];
float std_dev_rate1[24];
float temp_rate1[24];
float sum_rate[24];
float avg_rate[24];
float std_dev_rate[24];
float temp_rate[24];
struct dam dam_obj[10];
pthread_t inner_thread[10];
//Thread for increasing water in lower dam after delay
void *inner_function(void *no)
{

    int *num = no;
    if(*num != (n-1))
    {

        sleep(dam_obj[*num-1].delay);

    }
    else if(*num == (n-1))
    {

        sleep(dam_obj[*num].delay);

    }
    dam_obj[*num+1].unit_vol = dam_obj[*num+1].sto_capacity/(dam_obj[*num+1].max_height - dam_obj[*num+1].min_height);
    extra_height = extra_water/dam_obj[*num+1].unit_vol;
    dam_obj[*num+1].crnt_lvl+=extra_height;
    pthread_exit(NULL);

}
//Thread for forcasting 7 day details
void *days_function()
{

    while(days_count<7)
    {

        h=n-2;

        while(h>=(pos-1))
        {

            printf("Day-%d\tWorking Hours of dam %d:\t18hrs to 22hrs\n", days_count+1, h);
            dam_obj[h].water_req = (dam_obj[h].pro_capacity*dam_obj[h].work_hr)/(1000*dam_obj[h].stn_const);
            if((h-1)>-1)
            {

                dam_obj[h-1].work_hr = dam_obj[h].water_req*1000*dam_obj[h].stn_const/dam_obj[h-1].pro_capacity;
                dam_obj[h-1].work_hr_int = dam_obj[h-1].work_hr*10;
                temp_extra_w_hr_ref = dam_obj[h-1].work_hr_int%10;
                dam_obj[h-1].work_hr_int/=10;
                if(temp_extra_w_hr_ref>2)
                {

                    dam_obj[h-1].work_hr_int++;

                }

                dam_obj[h-1].work_hr_int-=4;

                //calculate the average and standard deviation of the rates
                jj=0;
                k1=1;
                flag1=1;
                while(flag1=1)
                {

                    if(jj==0 && k1==0)
                    {

                        flag1=0;
                        break;

                    }

                    if(jj>=18 && jj<=22 && (jj+dam_obj[h-1].work_hr_int)>=18 && (jj+dam_obj[h-1].work_hr_int)<=22)
                    {

                        rank1[jj]=25;
                        jj++;
                        sum_rate1[jj]=0;
                        avg_rate1[jj]=0;
                        std_dev_rate1[jj]=0;
                        continue;

                    }

                    rank1[jj]=jj;
                    k1=0;
                    sum_rate1[jj] = 0;
                    for(l1=0;l1<dam_obj[h-1].work_hr_int;l1++)
                    {

                        m1 = jj+l1;
                        if(m1>23)
                        {

                            m1-=24;

                        }
                        sum_rate1[jj]+=rate[m1];

                    }

                    avg_rate1[jj]=sum_rate1[jj]/extra_w_hr_int;

                    for(l1=0;l1<dam_obj[h-1].work_hr_int;l1++)
                    {

                        m1 = jj+l1;
                        if(m1>23)
                        {

                            m1-=24;

                        }

                        temp_rate1[m1]=rate[m1];
                        temp_rate1[m1]=pow((temp_rate1[m1]-avg_rate1[m1]),2);
                        std_dev_rate1[jj]+=temp_rate1[m1];

                    }

                    jj++;

                    if(jj>23)
                    {

                        jj-=24;

                    }

                }

                //Sorting the values
                for(jj=0;jj<(n-1);jj++)
                {

                    for(l1=0;l1<n-jj-1;l1++)
                    {

                        if((avg_rate1[l1]>avg_rate1[l1+1]) || ((avg_rate1[l1]==avg_rate1[l1+1]) && (std_dev_rate1[l1]>std_dev_rate1[l1+1])))
                        {

                            swap1=rank1[l1];
                            rank1[l1]=rank[l1+1];
                            rank[l1+1]=swap1;

                        }

                    }

                }

                printf("Day-%d\tWorking Hours of dam %d:\t18hrs to 22hrs\tand\t%dhrs to %dhrs\n", days_count+1, h-1, rank1[0], rank1[0]+dam_obj[h-1].work_hr_int);

            }

            h--;

        }

        while(g<(pos-1))
        {

            printf("Day-%d\tWorking Hours of dam 1:\t18hrs to 22hrs\n", days_count+1);
            dam_obj[g].water_req = dam_obj[g].pro_capacity*dam_obj[g].work_hr/(1000*dam_obj[g].stn_const);
            dam_obj[g+1].work_hr = dam_obj[g].water_req*1000*dam_obj[g+1].stn_const/dam_obj[g+1].pro_capacity;
            dam_obj[g+1].work_hr_int = dam_obj[g+1].work_hr*10;
            temp_extra_w_hr_ref = dam_obj[g+1].work_hr_int%10;
            dam_obj[g+1].work_hr_int/=10;
            if(temp_extra_w_hr_ref>2)
            {

                dam_obj[g+1].work_hr_int++;

            }
            dam_obj[g+1].work_hr_int-=4;

            //calculate the average and standard deviation of the rates
            jj=0;
            k1=1;
            flag1=1;
            while(flag1=1)
            {

                if(jj==0 && k1==0)
                {

                    flag1=0;
                    break;

                }

                if(jj>=18 && jj<=22 && (jj+dam_obj[g+1].work_hr_int)>=18 && (jj+dam_obj[g+1].work_hr_int)<=22)
                {

                    rank1[jj]=25;
                    jj++;
                    sum_rate1[jj]=0;
                    avg_rate1[jj]=0;
                    std_dev_rate1[jj]=0;
                    continue;

                }

                rank1[jj]=jj;
                k1=0;
                sum_rate1[jj] = 0;
                for(l1=0;l1<dam_obj[g+1].work_hr_int;l1++)
                {

                    m1 = jj+l1;
                    if(m1>23)
                    {

                        m1-=24;

                    }
                    sum_rate1[jj]+=rate[m1];

                }

                avg_rate1[jj]=sum_rate1[jj]/extra_w_hr_int;

                for(l1=0;l1<dam_obj[g+1].work_hr_int;l1++)
                {

                    m1 = jj+l1;
                    if(m1>23)
                    {

                        m1-=24;

                    }

                    temp_rate1[m1]=rate[m1];
                    temp_rate1[m1]=pow((temp_rate1[m1]-avg_rate1[m1]),2);
                    std_dev_rate1[jj]+=temp_rate1[m1];

                }

                jj++;

                if(jj>23)
                {

                    jj-=24;

                }

            }

            //Sorting the values
            for(jj=0;jj<(n-1);jj++)
            {

                for(l1=0;l1<n-jj-1;l1++)
                {

                    if((avg_rate1[l1]>avg_rate1[l1+1]) || ((avg_rate1[l1]==avg_rate1[l1+1]) && (std_dev_rate1[l1]>std_dev_rate1[l1+1])))
                    {

                        swap1=rank1[l1];
                        rank1[l1]=rank[l1+1];
                        rank[l1+1]=swap1;

                    }

                }

            }

            printf("Day-%d\tWorking Hours of dam %d:\t18hrs to 22hrs\tand\t%dhrs to %dhrs\n", days_count+1, g+2, rank1[0], rank1[0]+dam_obj[g+1].work_hr_int);
            g++;

        }

        dam_obj[n-1].water_req = dam_obj[g].water_req - dam_obj[g-1].water_req;
        dam_obj[n-1].work_hr = dam_obj[n-1].water_req*1000*dam_obj[n-1].stn_const/dam_obj[n-1].pro_capacity;
        dam_obj[n-1].work_hr_int = dam_obj[n-1].work_hr*10;
        temp_extra_w_hr_ref = dam_obj[n-1].work_hr_int%10;
        dam_obj[n-1].work_hr_int/=10;
        if(temp_extra_w_hr_ref>2)
        {

            dam_obj[n-1].work_hr_int++;

        }
        dam_obj[n-1].work_hr_int-=4;

        //calculate the average and standard deviation of the rates
        jj=0;
        k1=1;
        flag1=1;
        while(flag1=1)
        {

            if(jj==0 && k1==0)
            {

                flag1=0;
                break;

            }

            if(jj>=18 && jj<=22 && (jj+dam_obj[n-1].work_hr_int)>=18 && (jj+dam_obj[n-1].work_hr_int)<=22)
            {

                rank1[jj]=25;
                jj++;
                sum_rate1[jj]=0;
                avg_rate1[jj]=0;
                std_dev_rate1[jj]=0;
                continue;

            }

            rank1[jj]=jj;
            k1=0;
            sum_rate1[jj] = 0;
            for(l1=0;l1<dam_obj[n-1].work_hr_int;l1++)
            {

                m1 = jj+l1;
                if(m1>23)
                {

                    m1-=24;

                }
                sum_rate1[jj]+=rate[m1];

            }

            avg_rate1[jj]=sum_rate1[jj]/extra_w_hr_int;

            for(l1=0;l1<dam_obj[h-1].work_hr_int;l1++)
            {

                m1 = jj+l1;
                if(m1>23)
                {

                    m1-=24;

                }

                temp_rate1[m1]=rate[m1];
                temp_rate1[m1]=pow((temp_rate1[m1]-avg_rate1[m1]),2);
                std_dev_rate1[jj]+=temp_rate1[m1];

            }

            jj++;

            if(jj>23)
            {

                jj-=24;

            }

        }

        //Sorting the values
        for(jj=0;jj<(n-1);jj++)
        {

            for(l1=0;l1<n-jj-1;l1++)
            {

                if((avg_rate1[l1]>avg_rate1[l1+1]) || ((avg_rate1[l1]==avg_rate1[l1+1]) && (std_dev_rate1[l1]>std_dev_rate1[l1+1])))
                {

                    swap1=rank1[l1];
                    rank1[l1]=rank[l1+1];
                    rank[l1+1]=swap1;

                }

            }

        }

        printf("Day-%d\tWorking Hours of dam %d:\t18hrs to 22hrs\tand\t%dhrs to %dhrs\n", days_count+1, n-1, rank1[0], rank1[0]+dam_obj[n-1].work_hr_int);


    }

    pthread_exit(NULL);

}
//Thread function for working of dams
void *dam_function()
{

    diff_level = dam_obj[i].crnt_lvl - dam_obj[i].crnt_lvl_max;
    dam_obj[i].unit_vol = dam_obj[i].sto_capacity/(dam_obj[i].max_height - dam_obj[i].min_height);
    extra_water = diff_level * dam_obj[i].unit_vol;
    water_pu[i] = dam_obj[i].pro_capacity/(dam_obj[i].stn_const * 1000);
    extra_w_hr = extra_water/water_pu[i];
    extra_w_hr_int = extra_w_hr*10;
    extra_w_hr_ref = extra_w_hr_int%10;
    extra_w_hr_int/=10;
    if(extra_w_hr_ref>2)
    {

        extra_w_hr_int++;

    }

    //calculate the average and standard deviation of the rates
    j=0;
    k=1;
    flag=1;
    while(flag=1)
    {

        if(j==0 && k==0)
        {

            flag=0;
            break;

        }

        if(j>=18 && j<=22 && (j+extra_w_hr_int)>=18 && (j+extra_w_hr_int)<=22)
        {

            rank[j]=25;
            j++;
            sum_rate[j]=0;
            avg_rate[j]=0;
            std_dev_rate[j]=0;
            continue;

        }

        rank[j]=j;
        k=0;
        sum_rate[j] = 0;

        for(l=0;l<extra_w_hr_int;l++)
        {

            m = j+l;
            if(m>23)
            {

                m-=24;

            }
            sum_rate[j]+=rate[m];

        }

        avg_rate[j]=sum_rate[j]/extra_w_hr_int;
        std_dev_rate[j]=0;

        for(l=0;l<extra_w_hr_int;l++)
        {

            m = j+l;
            if(m>23)
            {

                m-=24;

            }
            temp_rate[m]=rate[m];
            temp_rate[m]=pow((temp_rate[m]-avg_rate[m]),2);
            std_dev_rate[j]+=temp_rate[m];

        }

        j++;

        if(j>23)
        {

            j-=24;

        }

    }

    //Sorting the values
    for(j=0;j<(n-1);j++)
    {

        for(l=0;l<n-j-1;l++)
        {

            if((avg_rate[l]>avg_rate[l+1]) || ((avg_rate[l]==avg_rate[l+1]) && (std_dev_rate[l]>std_dev_rate[l+1])))
            {

                swap=rank[l];
                rank[l]=rank[l+1];
                rank[l+1]=swap;

            }

        }

    }

    printf("Hours of extra running: %d\nExtra Working Hours for dam-%d: %d Hours - %d Hours\n", extra_w_hr_int, i, rank[0], rank[0]+extra_w_hr_int);

    if(i+1<n)
    {

        pthread_create (&inner_thread[i], NULL, (void *) &inner_function, &i);
        if(i == pos)
        {

            pthread_create (&inner_thread[pos], NULL, (void *) &inner_function, &pos);

        }

    }

    pthread_exit(NULL);

}

int main()
{

    pthread_t thread[10],days_thread;
    FILE *file = fopen ( "values.txt", "r" );
    dam_obj[n-1].work_hr = 4;
    dam_obj[0].work_hr = 24;
    //printf("Enter the number of dams:\t\t");
    fscanf(file, "%d\n",&n);
    //printf("\n\nThe branched dam should be given as the \'n\'th dam in the set\n\n\n");
    for(i=0;i<n;i++)
    {

        //printf("Enter the maximum height of dam-%d:\t",i+1);
        fscanf(file, "%f\n",&dam_obj[i].max_height);    
        //printf("Enter the minimum height of dam-%d:\t",i+1);
        fscanf(file, "%f\n",&dam_obj[i].min_height);    
        //printf("Enter the storage capacity of dam-%d:\t",i+1);
        fscanf(file, "%f\n",&dam_obj[i].sto_capacity);  
        //printf("Enter the production capacity of dam-%d:\t",i+1);
        fscanf(file, "%f\n",&dam_obj[i].pro_capacity);  
        //printf("Enter the station constant of dam-%d:\t",i+1);
        fscanf(file, "%f\n",&dam_obj[i].stn_const); 
        //printf("Enter the current level of dam-%d:\t",i+1);
        fscanf(file, "%f\n",&dam_obj[i].crnt_lvl);  
        //printf("Enter the time delay of dam-%d:\t\t",i+1);
        fscanf(file, "%f\n",&dam_obj[i].delay);

    }

    //printf("Enter the rates for the following hours:\n");
    for(i=0;i<24;i++)
    {

        //printf("%d-%d:\t\t\t",i,i+1);
        fscanf(file, "%f\n",&rate[i]);

    }

    if(n>2)
    {

        //printf("Enter the position at which the stage occurs:\t");
        fscanf(file, "%d\n",&pos);

    }

    for(i=0;(i<n && days_count<7);i++)
    {

        dam_obj[i].crnt_lvl_min=dam_obj[i].max_height * 0.6;
        dam_obj[i].crnt_lvl_max=dam_obj[i].max_height * 0.8;

        //If the current level is greater than allowed maximum level
        if(dam_obj[i].crnt_lvl_max < dam_obj[i].crnt_lvl)
        {
            pthread_create (&thread[i], NULL, (void *) &dam_function, NULL);
            if(i==(n-1))
            {

                i = -1;
                days_count++;

            }

        }

        //Normal Working Condition
        else if(((dam_obj[i].crnt_lvl<dam_obj[i].crnt_lvl_max) && (dam_obj[i].crnt_lvl>dam_obj[i].crnt_lvl_min)) && (main_flag == 1))
        {

            main_flag=0;
            pthread_create (&days_thread, NULL, (void *) &days_function, NULL);

        }

    }

    pthread_exit(NULL);

}

文件内容如下:

5
1758.69
1735.836
7.787
28
1.263
1758.69
2
847.6
844.86
1.614
36
.79
847.05
4
456.59
444
5.557
55
.41
452.9
3
253
237.74
4.55
116
.46
247.3
0
707.745
678.8
47.4
32
.472
703.8
2
7
5
6
3
8
3
6
4
5
7
9
1
3
2
4
5
7
8
4
6
7
3
5
9
3

我使用gcc -o project project.c -pthread -lpthread -lm在linux中编译了程序 但运行时它只返回一个 Segmentation Fault 。因此，我使用 gdb 编译了用于调试的代码，然后在运行时，gdb 显示了以下内容:

Starting program: /home/anver/project
[Thread debugging using libthread_db enabled]
[New Thread 0xb7e2db70 (LWP 3778)]
[New Thread 0xb762cb70 (LWP 3779)]
[New Thread 0xb6e2bb70 (LWP 3780)]
[New Thread 0xb662ab70 (LWP 3781)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xb762cb70 (LWP 3779)]
0x08049cd1 in dam_function () at project-file.c:504
504             std_dev_rate[j]+=temp_rate[m];

之后，当我打印 j、l 和 m 的值时，我发现 j、l 和 m 的值非常高，预计不会超过 23。有什么办法可以解决这个问题吗？提前致谢。

最佳答案

pthreads 标准指定，在一个线程上访问变量(而该变量在另一个线程中已修改或可能已修改)是未定义的行为。您的函数 days_function 使用变量 days_count 以及许多其他地方的许多其他变量来执行此操作。

说实话，看起来你不知道如何正确使用线程。

关于c - 多线程程序C中的段错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15933675/

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