After establishing the libcurl websocket connection, data transmission and reception cannot be monitored through curl_multi_poll()

Question

Websocket connection stage, curl_multi_poll() is useful for monitoring. However, during the data transmission and reception stage, curl_multi_poll() fails.

It is found that the CURL_POLL_REMOVE event occurs after the websocket connection is successful.

How can this problem be solved?

curl_easy_setopt(easy, CURLOPT_URL, "ws://xxx.com.cn");
curl_easy_setopt(easy, CURLOPT_CONNECT_ONLY, 2L); // 2 => WebSocket(1 => TCP)
curl_easy_setopt(easy, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS); // 可选,TLS/HTTP2
curl_easy_setopt(easy, CURLOPT_TIMEOUT, 30L);
curl_multi_add_handle(multi, easy);
int running = 0;
curl_multi_perform(multi, &running);
while (running) {
 int numfds = 0;
 CURLMcode mc = curl_multi_poll(multi, NULL, 0, 1000, &numfds);
 if (mc != CURLM_OK) break;
 curl_multi_perform(multi, &running);
}
curl_ws_send(easy, msg, strlen(msg), &sent, 0, CURLWS_TEXT);
rc = curl_ws_recv(easy, buf, sizeof(buf), &rlen,&meta);
if (rc == CURLE_AGAIN) {
 /* error code, Even if data is received, it will cause a 1000ms delay. */
 curl_multi_poll(multi, NULL, 0, 1000, &numfds); 
}

• Kamran: Use CURLINFO_ACTIVESOCKET + your own event loop instead of relying on curl_multi_poll() post-upgrade.
• user31600459: Does curl_multi_poll() not support the transmission and reception of WebSocket data? How to use CURLINFO_ACTIVESOCKET? Here's a simple example. I need to do it in a non-polling manner.
• 3CEZVQ: The first comment is very poor.