信号处理程序不起作用 [英] signal handler not working

问题描述

我在我的代码中使用了 czmq 和 zmq 库.我通过在 main 中调用 signal 为 SIGINT 注册了一个信号处理程序.代码如下所示:

I'm using czmq and zmq libraries in my code. I've registered a signal handler for SIGINT by calling signal in main. The code looks like this:

#include "czmq.h"

void sig_int(int signal);

void* pub_handler(){
    zctx_t *context = zctx_new ();
    void *publisher = zsocket_new (context, ZMQ_PUB);

    zsocket_connect (publisher, "tcp://localhost:5555");

    sleep(1);

    char topic[20] = "REQ: speedlimit";

 // while (true)
    {
        sleep( randof(10) );
        zstr_sendm (publisher, topic);
        zstr_send (publisher, "driver analysis data");
    }
    zctx_destroy (&context);

}

void* sub_handler(){
    zctx_t *context = zctx_new();
    void *subscriber = zsocket_new (context, ZMQ_SUB);

    zsocket_connect (subscriber, "tcp://localhost:5557");

    srandom ((unsigned) time (NULL));

    char subscription [20] = "RESP: speedlimit" ;

    zsocket_set_subscribe (subscriber, subscription);

    while (true) {
        char *topic = zstr_recv (subscriber);
        if(!topic)
            break;
        char *data = zstr_recv (subscriber);
        assert (streq (topic, subscription));
        puts (topic);
        puts (data);
        free (topic);
        free (data);
    }
    zctx_destroy (&context);
}

int main(int argc, const char *argv[])
{
    pthread_t pub_id, sub_id;
    signal (SIGINT, sig_int);
    pthread_create(&pub_id, NULL, pub_handler, NULL);
    pthread_create(&sub_id, NULL, sub_handler, NULL);

    pthread_join(pub_id, NULL);
    pthread_join(sub_id, NULL);

    return 0;
}

void sig_int(int signal){
    printf (" Interrupted\n");
    exit(0);
}

编译为 gcc -o app app.c -lpthread -lczmq -lzmq.

上述代码在ctrl+c中断时不会进入信号处理程序.

The above code doesn't get into signal handler when ctrl+c interrupt is given.

czmq 或 zmq 库有什么问题，应该如何处理?

what is the problem with czmq or zmq library and how it should be handled?

推荐答案

zctx 文档 表示 zctx 为 SIGINT 和 SIGTERM 设置了自己的信号处理程序，可能会覆盖您的信号处理程序.

The documentation for zctx says that zctx sets up its own signal handler for SIGINT and SIGTERM, probably overriding your signal handler.

设置信号(SIGINT 和 SIGTERM)处理以便阻塞调用例如 zmq_recv() 和 zmq_poll() 会在用户按下时返回Ctrl-C.

Sets up signal (SIGINT and SIGTERM) handling so that blocking calls such as zmq_recv() and zmq_poll() will return when the user presses Ctrl-C.

它还说 zctx 已被弃用，取而代之的是 zsock，它似乎没有根据其文档设置信号处理程序.所以我的第一个建议是使用新的 zsock 套接字 API.

It also says that zctx is deprecated in favor of zsock, which doesn't appear to setup a signal handler according to its documentation. So my first suggestion is to use the new zsock socket API.

然而，似乎在这两种情况下你也可以调用 zsys_handler_set(NULL);(记录在 此处) 以明确禁用 CZMQ 中的默认 SIGINT/SIGTERM 处理.

However, it seems that in both cases you can also call zsys_handler_set(NULL); (documented here) to explicitly disable the default SIGINT/SIGTERM handling in CZMQ.

PS:printf 不是异步信号安全的，这意味着它不应在信号处理程序中使用.请参阅此处获取异步信号安全函数列表在 POSIX 中.

PS: printf is not async-signal-safe, meaning that it should not be used in a signal handler. See here for a list of async-signal-safe functions in POSIX.

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