c - mq_open 给出 "too many open files"

Question

我使用以下代码创建了一个消息队列。前几次它工作正常。

int main()
{
    mqd_t mqdes;
    char mq_name[10] = "/mq";
    int oflag = O_CREAT | O_RDWR, ret;
    struct mq_attr attr;

    attr.mq_maxmsg = 1024;
    attr.mq_msgsize = 2048; 

    mqdes = mq_open(mq_name, oflag, 0766, &attr);
    if(mqdes == -1) {
            perror("mq_open");
            if(errno == EMFILE)
                    perror("EMFILE");
            exit(1);
    }

    printf("mqueue created, mq_descriptor: %d\n", mqdes);

    ret = mq_close(mqdes);
    if(ret == -1) {
            perror("mq_close");
            exit(2);
    }
    printf(" mq closed successful\n");


    return 0;
}

之后报如下错误

mq_open: Too many open files
EMFILE: Too many open files

但为什么会出现此错误？我如何才能看到诸如 ipcs 之类的 possix 消息队列适用于系统 V？

Answer 1

尝试设置资源限制:

#include <sys/resource.h>

struct rlimit rlim;
memset(&rlim, 0, sizeof(rlim));
rlim.rlim_cur = RLIM_INFINITY;
rlim.rlim_max = RLIM_INFINITY;

setrlimit(RLIMIT_MSGQUEUE, &rlim);