Difficulty Creating Pthreads (Error 22) - c

Question

Learning about pthreads, but I'm having trouble getting them created. Here is my output and the gdb information:
In main(), creating thread 1
ERROR: return code from pthread_create() is 22 for thread 1
In main(), creating thread 2
ERROR: return code from pthread_create() is 22 for thread 2
In main(), creating thread 3
ERROR: return code from pthread_create() is 22 for thread 3
In main(), creating thread 4
ERROR: return code from pthread_create() is 22 for thread 4
In main(), creating thread 5
ERROR: return code from pthread_create() is 22 for thread 5
Program received signal SIGSEGV, Segmentation fault. 0xb7fb4d8a in
pthread_join (threadid=76038327, thread_return=0x0)
at pthread_join.c:46 46 pthread_join.c: No such file or directory.
And here is my code:
#include <stdlib.h>
#include <stdio.h>
#include <strings.h>
#include <errno.h>
#include <pthread.h>
#include <unistd.h>
#define SBUFSIZE 1025
char errorstr[SBUFSIZE];
FILE* inputfp[5];
void* f(void* inpFile) {
fprintf(stderr, "%s\n", (char*)inpFile);
return NULL;
}
int main (int argc, char* argv[]) {
int i;
/* Thread Variables */
pthread_attr_t attr;
pthread_t *th[argc-2]; //one thread for each input file
/* allocate memory for the threads */
for (i = 0; i < (argc-2); i++) {
th[i] = (pthread_t *) malloc(sizeof(pthread_t));
inputfp[i] = fopen(argv[i], "r");
if (!inputfp[i]) {
sprintf(errorstr, "Error Opening Input File: %s", argv[i]);
perror(errorstr);
}
}
/* Create one thread for each input file */
for (i = 1; i < (argc - 1); i++) {
fprintf (stderr, "In main(), creating thread %1d\n", i);
int rc = pthread_create (th[i], &attr, f, inputfp[i-1]);
if (rc) {
printf("ERROR: return code from pthread_create() is %d for thread %d\n",
rc, i);
}
}
/* wait for the threads to finish */
for (i = 1; i < (argc - 1); i++) {
pthread_join(*th[i], 0);
}
return EXIT_SUCCESS;
}
I'm missing something, but I don't know what. Can anyone help? Thank you!
EDIT: Here is how I changed the code per the suggestion from Joachim Pileborg. I'm still getting error 22 returning from pthread_create(), but the SIGSEGV error on pthread_join is no longer occurring.
Anyone have any suggestions about how I can get the pthread_create() to return 0 (indicating a successful thread creation)? Thanks again!
int main (int argc, char* argv[]) {
int i;
/* Thread Variables */
pthread_attr_t attr;
pthread_t *th[argc-2]; //one thread for each input file
/* allocate memory for the threads */
for (i = 0; i < (argc-2); i++) {
th[i] = (pthread_t *) malloc(sizeof(pthread_t));
printf("%s\n", argv[i+1]);
inputfp[i] = fopen(argv[i+1], "r");
if (!inputfp[i]) {
sprintf(errorstr, "Error Opening Input File: %s", argv[i]);
perror(errorstr);
}
}
/* Create one thread for each input file */
for (i = 0; i < (argc - 2); i++) {
fprintf (stderr, "In main(), creating thread %1d\n", i);
int rc = pthread_create (th[i], &attr, f, inputfp[i]);
if (rc) {
printf("ERROR: return code from pthread_create() is %d for thread %d\n",
rc, i);
}
}
/* wait for the threads to finish */
for (i = 0; i < (argc - 2); i++) {
pthread_join(*th[i], 0);
}
return EXIT_SUCCESS;
}

Answer 1

You have one loop where you loop from zero to argc - 3, and uses the correct indexes (zero to "size of array minus one".
Then you have two loops where you loop from one to argc - 2, and use indexes from one to "size of array".
You should use the same loop as the first one in all three places.