#include "curl/curl.h"

int main(int argc, char** argv)
{
    CURLM *multi = curl_multi_init();
    curl_multi_setopt(multi, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
    curl_multi_setopt(multi, CURLMOPT_MAX_HOST_CONNECTIONS, 4);

    int i;
    for (i = 0; i < 5; i++) {
        CURL *easy = curl_easy_init();
        curl_easy_setopt(easy, CURLOPT_URL, "https://httpbin.org/delay/2");
        curl_easy_setopt(easy, CURLOPT_VERBOSE, 1);
        curl_easy_setopt(easy, CURLOPT_PIPEWAIT, 1);
        curl_easy_setopt(easy, CURLOPT_NOPROXY, "");
        curl_easy_setopt(easy, CURLOPT_PROXY, "http://my-http-proxy:3128");

        curl_multi_add_handle(multi, easy);
    }

    int running= 1;
    while (running) {
        int numfds;
        curl_multi_perform(multi, &running);
        curl_multi_wait(multi, NULL, 0, 1000, &numfds);
    }

    curl_multi_cleanup(multi);

    return 0;
}

* Connection #0 to host my-http-proxy left intact
* Found bundle for host httpbin.org: 0x1b99f00 [serially]
* Server doesn't support multiplex yet, wait
* No connections available.