分割错误(核心转储)C编程pthreads直方图
问题描述:
我使用pthreads做了Histogram,经过长时间的努力后..最后它说'Segmentation Fault(Core Dumped)'。不幸的是我有这条线p =(struct1 *)malloc(sizeof(struct1));从命令行获得值的结构变量..所以这被清除了..感谢@DNT让我知道..分割错误(核心转储)C编程pthreads直方图
现在,当我尝试执行下列程序..它有时会显示输出,有时它会发送到which_bin函数并打印以下内容:
输出类型1(这不是正确的输出): Data = 0.000000不属于bin! 退出
输出型2(几乎HISTO的正确的输出随时间通过螺纹采取): 10.000-28.000: 28.000-46.000: 46.000-64.000: 64.000-82.000: 82.000-100.000:XXXXXXXXXX 该代码将定时把0.000415秒
我的疑问句的是,为什么同样的前卫跑时表现出不同的输出..我很困惑的其所以然寻找..
这里是我的代码..
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include "timer.h"
void Usage(char prog_name[]);
//void Get_args(void *p);
void Gen_data(void *p);
void Gen_bins(void *p);
int Which_bin(void *p);
void Print_histo(void *p);
void func(void *p);
struct test
{
int bin_count, i, bin;
float min_meas, max_meas;
float* bin_maxes;
int* bin_counts;
int data_count;
float* data;
};
typedef struct test struct1;
int main(int argc, char* argv[])
{
double start, finish, elapsed;
GET_TIME(start);
struct1 *p;
pthread_t th1, th2, th3;
p=(struct1 *)malloc(sizeof(struct1));
if (argc != 5)
Usage(argv[0]);
p->bin_count = strtol(argv[1], NULL, 10);
p->min_meas = strtof(argv[2], NULL);
p->max_meas = strtof(argv[3], NULL);
p->data_count = strtol(argv[4], NULL, 10);
p->bin_maxes = malloc(p->bin_count*sizeof(float));
p->bin_counts = malloc(p->bin_count*sizeof(int));
p->data = malloc(p->data_count*sizeof(float));
pthread_create(&th1,NULL,(void*) Gen_data,(void*) p);
pthread_create(&th2,NULL,(void*) Gen_bins,(void*) p);
pthread_create(&th3,NULL,(void*) func,(void*) p);
printf("Hi\n");
pthread_join(th1,NULL);
pthread_join(th2,NULL);
pthread_join(th3,NULL);
Print_histo(p);
free(p->data);
free(p->bin_maxes);
free(p->bin_counts);
GET_TIME(finish);
elapsed = finish - start;
printf("The code to be timed took %f seconds\n", elapsed);
return 0;
} /* main */
void func(void *p)
{
int i;
struct1 *args;
args=(struct1*)p;
for (i = 0; i < args->data_count; i++)
{
args->bin = Which_bin(args);
args->bin_counts[args->bin]++;
}
# ifdef DEBUG
printf("bin_counts = ");
for (i = 0; i < args->bin_count; i++)
printf("%d ", args->bin_counts[i]);
printf("\n");
# endif
}
/*---------------------------------------------------------------------
* Function: Usage
* Purpose: Print a message showing how to run program and quit
* In arg: prog_name: the name of the program from the command line
*/
void Usage(char prog_name[] /* in */)
{
fprintf(stderr, "usage: %s ", prog_name);
fprintf(stderr, "<bin_count> <min_meas> <max_meas> <data_count>\n");
exit(0);
} /* Usage */
void Gen_data(void *p)
{
struct1 *args;
args=(struct1*)p;
int i;
srandom(0);
for (i = 0; i < args->data_count; i++)
args->data[i] = args->min_meas + (args->max_meas - args->min_meas)*random()/((double) RAND_MAX);
#ifdef DEBUG
printf("data = ");
for (i = 0; i < args->data_count; i++)
printf("%4.3f ", args->data[i]);
printf("\n");
#endif
} /* Gen_data */
void Gen_bins(void* p)
{
struct1 *args;
args=(struct1*)p;
float bin_width;
int i;
bin_width = (args->max_meas - args->min_meas)/args->bin_count;
for (i = 0; i < args->bin_count; i++)
{
args->bin_maxes[i] = args->min_meas + (i+1)*bin_width;
args->bin_counts[i] = 0;
}
# ifdef DEBUG
printf("bin_maxes = ");
for (i = 0; i < args->bin_count; i++)
printf("%4.3f ", args->bin_maxes[i]);
printf("\n");
# endif
}
int Which_bin(void* p)
{
struct1 *args;
args=(struct1*)p;
int bottom = 0, top = args->bin_count-1;
int mid;
float bin_max, bin_min;
while (bottom <= top)
{
mid = (bottom + top)/2;
bin_max = args->bin_maxes[mid];
bin_min = (mid == 0) ? args->min_meas: args->bin_maxes[mid-1];
if (*(args->data) >= bin_max)
bottom = mid+1;
else if (*(args->data) < bin_min)
top = mid-1;
else
return mid;
}
fprintf(stderr, "Data = %f doesn't belong to a bin!\n", args->data);
fprintf(stderr, "Quitting\n");
exit(-1);
}
void Print_histo(void *p)
{
struct1 *args;
args=(struct1*)p;
int i, j;
float bin_max, bin_min;
for (i = 0; i < args->bin_count; i++)
{
bin_max = args->bin_maxes[i];
bin_min = (i == 0) ? args->min_meas: args->bin_maxes[i-1];
printf("%.3f-%.3f:\t", bin_min, bin_max);
for (j = 0; j < args->bin_counts[i]; j++)
printf("X");
printf("\n");
}
}
/* Print_histo */
我想知道该程序是否在逻辑上错误?如果在这种情况下它在逻辑上是错误的,那么为什么它有时会显示直方图输出。谢谢!
请使用调试器来缩小您的问题。 – Mat
在进行高级编程(如多线程)之前,您需要学习C的基础知识。如果你从main()和向下读你的程序,你应该能够在几秒钟内找到bug。 – Lundin