$ cat -n ostep/code/intro/threads.c
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include "common.h"
4 #include "common_threads.h"
5
6 volatile int counter = 0;
7 int loops;
8
9 void *worker(void *arg) {
10 int i;
11 for (i = 0; i < loops; i++) {
12 counter++;
13 }
14 return NULL;
15 }
16
17 int main(int argc, char *argv[]) {
18 if (argc != 2) {
19 fprintf(stderr, "usage: threads <loops>\n");
20 exit(1);
21 }
22 loops = atoi(argv[1]);
23 pthread_t p1, p2;
24 printf("Initial value : %d\n", counter);
25 Pthread_create(&p1, NULL, worker, NULL);
26 Pthread_create(&p2, NULL, worker, NULL);
27 Pthread_join(p1, NULL);
28 Pthread_join(p2, NULL);
29 printf("Final value : %d\n", counter);
30 return 0;
31 }
$
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-
$ ./threads 10
Initial value : 0
Final value : 20
$ ./threads 100
Initial value : 0
Final value : 200
$ ./threads 1000
Initial value : 0
Final value : 2000
$ ./threads 10000
Initial value : 0
Final value : 19897
$ ./threads 10000
Initial value : 0
Final value : 15562
$ ./threads 10000
Initial value : 0
Final value : 14179
$ ./threads 100000
Initial value : 0
Final value : 103750
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