UDP echo server with one thread per client - c

Question

I had a simple TCP echo server with one thread per client (it works), so i tried to transform it into UDP but faced problem after running server:
"pthread_create() resource temporarily unavailable"
. Here is my server code:
#include <errno.h>
#include <netinet/in.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
#define PORT 1027
#define BACKLOG 5
#define MAXLINE 256
#define SA struct sockaddr
typedef struct serve_clientArg {
int socket;
SA *addr;
socklen_t addrlen;
} SCARGS;
void Pthread_create(pthread_t *thread, pthread_attr_t *attr,
void *(*start_routine)(void *), void *arg)
{
int rc;
rc = pthread_create(thread, attr, start_routine, arg);
if(rc) {
errno = rc;
error("pthread_create()");
}
}
reads() and writen() are using recvfrom() and sendto() functions
void *serve_client(void* arg)
{
char s[MAXLINE];
ssize_t rc;
SCARGS *args = Malloc(sizeof (SCARGS));
args = (SCARGS*) arg;
int socket = args->socket;
SA *addr = args->addr;
socklen_t addrlen = args->addrlen;
free(arg);
pthread_detach(pthread_self());
while((rc = reads(socket, s, MAXLINE, addr, &addrlen)) > 0) {
writen(socket, s, rc, addr, addrlen);
}
Close(socket);
return NULL;
}
int main(void)
{
int socket;
struct sockaddr_in servaddr;
struct sockaddr_in cliaddr;
SCARGS *arg;
pthread_t thread;
socket = Socket(AF_INET, SOCK_DGRAM, 0);
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
Bind(socket, (SA *) &servaddr, sizeof(servaddr));
for(;;) {
arg = Malloc(sizeof (SCARGS));
arg->socket = socket;
arg->addr = (SA*) &cliaddr;
arg->addrlen = sizeof (cliaddr);
Pthread_create(&thread, NULL, serve_client, (void*) arg);
}
return 0;
}
I also had a TCP client and after transformation into UDP it works. I think i have done a stupid mistake, but i cant find it... Please help me find mistakes!

Answer 1

for(;;) {
arg = Malloc(sizeof (SCARGS));
arg->socket = socket;
arg->addr = (SA*) &cliaddr;
arg->addrlen = sizeof (cliaddr);
Pthread_create(&thread, NULL, serve_client, (void*) arg);
}
You allocate memory and create new threads inside an endless loop with no kind of blocking (as you might have done in TCP with accept). Therefore it quickly runs out of resources:
"pthread_create() resource temporarily unavailable"
Apart from that you use the same socket in all threads. But when you have only a single socket it does not really make sense to have multiple threads handling it. I'm not sure what you were trying to achieve with this design.