Concurrent TCP server using threads - c

Question

I'm trying to create a concurrent TCP server which accepts multiple(N connections) where N is known.(e.g.N=8) So I'm trying to create a prethreaded TCP server.
.....
for(i=0;i<NUMBER_OF_CONNECTIONS;i++)
{
CreateThreads(i);
}
return 0;
}
//Create threads to handle the connection
void CreateThreads( int i )
{
pthread_create(&thread_tid[i], NULL, thread_function, (void *) i);
return;
}
void* thread_function(void *arg)
{
puts("In thread_function");
int client_soc,clilen;
struct sockaddr_in *clientaddr;
if( (clientaddr = malloc(addrlen)) == NULL)
printf("malloc Error\n");
printf("thread %d starting\n", (int) arg);
while(1)
{
clilen = sizeof(struct sockaddr_in);
pthread_mutex_lock(&mlock);
puts("Calling accept \n");
if ( (client_soc = accept(socket_desc, (struct sockaddr *)&clientaddr,(socklen_t*)&clilen)) < 0)
{
printf("accept error\n");
}
pthread_mutex_unlock(&mlock);
printf("Process Request...calling connection handler \n");
connection_handler(client_soc); /* process request */
close(client_soc);
}
}
//This will handle connection for each client
void *connection_handler(void *socket_desc)
{
//Receive and process.....
return 0;
}
In the above code threads are created and the thread_function() gets called but it doesn't work as expected. The program comes to an end after calling the thread_function() till then a few threads get created.
I actually want the "N" number of threads to get created and wait for clients to connect(using accept()). Once connected i want to receive/collect data (or) sending commands etc. That's the reason i have connection_handler() but i'm stuck before that.
Can any one pls try to correct the thread_function() function ? I'm kind of getting stuck here.Thanks.
UPDATE
The program is based on the
http://www.cse.fau.edu/~jie/research/publications/Publication_files/roussevwu.pdf
Look at section 3.2 for using lock and accept.

Answer 1

The program comes to an end after calling the thread_function()
The problem is that after you create the threads the main thread falls through and ends the program. You should call pthread_join.
There's a problem with your approach. In your code you lock mlock and then you accept(2). You are calling a blocking function in a critical section. This severely limits parallelism, thus defeating much of the purpose of the threads.
You could try an approach where the main thread accepts and dispatches the new sockets to threads.