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

static long long counter = 0;
static long long loops = 0;

static void *worker(void *arg) {
    (void)arg;
    for (long long i = 0; i < loops; i++) {
        counter += 1;  // 故意不加锁：会丢更新
    }
    return NULL;
}

static long long parse_ll(const char *s, const char *name) {
    errno = 0;
    char *end = NULL;
    long long v = strtoll(s, &end, 10);
    if (errno != 0 || end == s || *end != '\0' || v < 0) {
        fprintf(stderr, "invalid %s: %s\n", name, s);
        exit(1);
    }
    return v;
}

int main(int argc, char **argv) {
    if (argc != 3) {
        fprintf(stderr, "usage: %s <loops> <threads>\n", argv[0]);
        return 1;
    }

    loops = parse_ll(argv[1], "loops");
    long long num_threads_ll = parse_ll(argv[2], "threads");

    if (num_threads_ll <= 0 || num_threads_ll > 1000000) {
        fprintf(stderr, "threads out of range: %lld\n", num_threads_ll);
        return 1;
    }

    int num_threads = (int)num_threads_ll;

    pthread_t *threads = (pthread_t *)malloc(sizeof(pthread_t) * (size_t)num_threads);
    if (!threads) {
        perror("malloc");
        return 1;
    }

    printf("Initial value: %lld\n", counter);

    for (int i = 0; i < num_threads; i++) {
        int rc = pthread_create(&threads[i], NULL, worker, NULL);
        if (rc != 0) {
            fprintf(stderr, "pthread_create failed (rc=%d)\n", rc);
            free(threads);
            return 1;
        }
    }

    for (int i = 0; i < num_threads; i++) {
        pthread_join(threads[i], NULL);
    }

    long long expected = loops * num_threads_ll;
    printf("Expected: %lld\n", expected);
    printf("Final value: %lld\n", counter);
    printf("Lost updates: %lld\n", expected - counter);

    free(threads);
    return 0;
}

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import sys
import threading


counter = 0
loops = 0


def worker():
    global counter
    for _ in range(loops):
        counter += 1


def main():
    global loops

    if len(sys.argv) != 3:
        print("usage: python race.py <loops> <threads>", file=sys.stderr)
        sys.exit(1)

    loops = int(sys.argv[1])
    num_threads = int(sys.argv[2])

    threads = []

    print("Initial value:", counter)

    for _ in range(num_threads):
        t = threading.Thread(target=worker)
        threads.append(t)
        t.start()

    for t in threads:
        t.join()

    print("Expected:", loops * num_threads)
    print("Final value:", counter)
    print("Lost updates:", loops * num_threads - counter)


if __name__ == "__main__":
    main()

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import sys
import threading
import time


counter = 0
loops = 0

def one():
    return 1


def worker():
    global counter
    for _ in range(loops):
        counter += one()


def main():
    global loops

    if len(sys.argv) != 3:
        print("usage: python race.py <loops> <threads>", file=sys.stderr)
        sys.exit(1)

    loops = int(sys.argv[1])
    num_threads = int(sys.argv[2])

    threads = []

    print("Initial value:", counter)

    for _ in range(num_threads):
        t = threading.Thread(target=worker)
        threads.append(t)
        t.start()

    for t in threads:
        t.join()

    print("Expected:", loops * num_threads)
    print("Final value:", counter)
    print("Lost updates:", loops * num_threads - counter)


if __name__ == "__main__":
    main()