$ diff -u test.c.original test.c
--- test.c.original     2022-09-07 11:10:57.427143497 -0700
+++ test.c      2022-09-07 11:18:48.435146489 -0700
@@ -5,6 +5,7 @@
 #include <arpa/inet.h>
 #include <unistd.h>
 #include <pthread.h>
+#include <fcntl.h>

 void *recv_thread(void *arg)
 {
@@ -14,8 +15,9 @@
     char recvbuf[1024] = {0};
     while(1)
     {
-        recvfrom(socket_fd, recvbuf, 1024, 0,(struct sockaddr*)&recv_addr,&addrlen);
-        printf("[recv from %s:%d]%s \n",inet_ntoa(*(struct in_addr*)&recv_addr.sin_addr.s_addr),ntohs(recv_addr.sin_port),recvbuf);
+        int rv = recvfrom(socket_fd, recvbuf, 1024, 0,(struct sockaddr*)&recv_addr,&addrlen);
+        if (rv > 0)
+          printf("[recv from %s:%d]%s \n",inet_ntoa(*(struct in_addr*)&recv_addr.sin_addr.s_addr),ntohs(recv_addr.sin_port),recvbuf);
     }
 }

@@ -32,9 +34,10 @@
        }
     struct sockaddr_in local_addr = {0};
     local_addr.sin_family = AF_INET;
-    local_addr.sin_addr.s_addr = inet_addr("192.168.0.107");
+    local_addr.sin_addr.s_addr = inet_addr("7.0.0.2");
     local_addr.sin_port = htons(12341);
     bind(sockfd, (struct sockaddr*)&local_addr, sizeof(local_addr));
+    fcntl(sockfd, F_SETFL, O_NONBLOCK);
        ret = pthread_create(&th, NULL, recv_thread, &sockfd);


@@ -48,9 +51,10 @@
        }
     struct sockaddr_in local_addr2 = {0};
     local_addr2.sin_family = AF_INET;
-    local_addr2.sin_addr.s_addr = inet_addr("192.168.0.107");
+    local_addr2.sin_addr.s_addr = inet_addr("7.0.0.2");
     local_addr2.sin_port = htons(12342);
     bind(sockfd2, (struct sockaddr*)&local_addr2, sizeof(local_addr2));
+    fcntl(sockfd2, F_SETFL, O_NONBLOCK);
        ret2 = pthread_create(&th2, NULL, recv_thread, &sockfd2);

        void *status;