Wierd behaviour inside thread function - c

Question

I have a server program written in C with a thread function join_handler. When i invoke this function in main- nothing after the statement -- printf("inside join handler %d",newsock); executes inside the thread function .
#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
#include<string.h>
#include<stdlib.h>
#include<arpa/inet.h>
#include<pthread.h>
#define SERVER_PORT 5498
#define MAX_LINE 256
#define MAX_PENDING 5
#define MAXNAME 256
int req_no;
char packet_type[50];
//void* join_handler(struct*);
struct packet{
short type;
char data[MAXNAME];
};
struct packet packet_reg;
struct global_table{
int sockid;
int reqno;
};
struct global_table record[20];
void *join_handler(void *rec)
{
//pthread_mutex_t my_mutex= PTHREAD_MUTEX_INITIALIZER;
int *newsock;
newsock=(int*)rec;
printf("inside join handler %d",newsock); /// the last statement which gets executed
printf("\n %d",newsock);
if(recv(newsock,&packet_reg,sizeof(packet_reg),0)<0)
{
printf("\n Could not receive \n");
exit(1);
}
printf("\n joinhandler sockid is %d",newsock);
//other operation
pthread_exit(NULL);
}
int main(int argc, char* argv[])
{
pthread_t threads[2];
struct sockaddr_in sin;
struct sockaddr_in clientAddr;
char buf[MAX_LINE];
int s, new_s;
struct in_addr addr;
struct hostent *host;
int len;
struct registrationTable
{
int port;
char name[MAXNAME];
int req_no;
};
struct registrationTable table[10];
int *exit_value;
req_no=0;
char clientname[500];
/* setup passive open */
if((s = socket(PF_INET, SOCK_STREAM, 0)) < 0){
perror("tcpserver: socket");
exit(1);
}
/* build address data structure */
bzero((char*)&sin, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
sin.sin_port = htons(SERVER_PORT);
if(bind(s,(struct sockaddr *)&sin, sizeof(sin)) < 0){
perror("tcpclient: bind");
exit(1);
}
listen(s, MAX_PENDING);
/* wait for connection, then receive and print text */
while(1){
if((new_s = accept(s, (struct sockaddr *)&clientAddr, &len)) < 0){
perror("tcpserver: accept");
exit(1);
}
recv(new_s,&packet_reg, sizeof(packet_reg), 0);
if(recv(new_s,&packet_reg, sizeof(packet_reg), 0)<0)
{
printf("\n Could not receive first registration packet \n");
exit(1);
}
pthread_create(&threads[0],NULL,join_handler,new_s);
pthread_join(threads[0],&exit_value);
}
}

Answer 1

You won't see any output until a \n.
Therefore, you won't see this line executed:
printf("\n %d",newsock);
That doesn't mean it isn't executing, just that the output is buffered and you won't see it until recv receives something. But, my guess is it won't until you send something back to the client, since you read the first packet before starting the thread.