Why can't I get system V message queues with fork () working?

I have a program here:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ipc.h>
#include <sys/types.h>
#include <sys/msg.h>
#include <sys/wait.h>
#include <errno.h>

#include "linkedlist.h"
#include "globals.h"
#include "card.h"
#include "logging.h"
#include "stack.h"
#include "servers.h"
#include "player.h"

#define VERSION "0.1"

#define ERR -1

/*
 * Main function runs, loads 5 named table objects. For each table
 * created a fork is created for that specific table object that
 * allows each table to run independently.
 *
 * Usernames details are also created and prepared. These are hardcoded
 * until I add database logic later.
 *
 * After the tables are prepared, the main function starts a server
 * listening thread that waits for UNIX sockets to connect to it. When
 * they arrive it spawns a handling thread that does a quick login check
 * and then asks the user which of the named tables they want to play on
 *
 * The socket information is then connected to the table, so the table can
 * then communicate with user. When the table is full, the table algorithm
 * is responcible for basically looping contineously, creating new "games"
 * until only one player is left. He is the winner. When he wins, the table
 * exits.
 *
 * the game loop does all the real work for the texas holdem game, hosting
 * rounds of bets, dealing cards etc.
 */

void table_process(int tables_id);
void main_game_loop(void);

int main(int argc, char **argv)
{
  int main_process_id;
  int connection_process_id;

  char table_config_name[8];
  char *table_name;
  stack *my_deck;
  card *current_card;
  int i;
  int s;

  printf("------------ PRT POKER -----------\nA texas holdem poker server\n~~~~Version: %s~~~~~~~\n", VERSION);

  config_load("poker.conf");
  logging_init();

  if (key = ftok("/mnt/mydocuments/git/texas_holdem/poker", 'a') == -1)
  {
    logging_critical("Call to ftok failed");
    exit(1);
  }

//  if ((msg_queue = msgget(key, 0644 | IPC_CREAT)) == -1)
//  {
//    logging_critical("call to msgget failed");
//    exit(1);
//  }

  //read int the list of tables from the configuration file

  config_get_int("players_per_table", &player_count);
  logging_info("players per table: %i", *player_count);

  config_get_int("table_count", &table_count);
  logging_info("number of tables: %i", *table_count);

  table_names = malloc(sizeof(char*) * (*table_count));

  logging_info("Table count: %d", *table_count);

  for (i = 0; i < *table_count; i++)
  {
    sprintf(table_config_name, "table_%d", (i + 1));  
    config_get_string(table_config_name, &table_name);

    table_names[i] = table_name;

    logging_info("Created table %d: %s", i, table_name);

    if (fork() == 0)
    {
      table_process(i);
      _exit(0);
    }
  }

  main_process_id = getpid();

  connection_process_id = fork();
  logging_info("connecton process: %d", connection_process_id);

  if (connection_process_id == 0)
  {
    wait_for_players();
    _exit(0);
  }
  else
    waitpid(connection_process_id, &s, 0);

  logging_info("Application ended");
  return 0;
}

void table_process(int table_id)
{
  linkedlist *players;
  player *p;
  int players_added;

  if ((msg_queue = msgget(key, 0644 | IPC_CREAT)) == -1)
  {
    logging_critical("call to msgget failed");
    exit(1);
  }

  logging_info("table %s (%i) running in process %d", table_names[table_id], table_id, getpid());

  players = linkedlist_new();

  players_added = *player_count;
  while (players_added > 0)
  {
    logging_info("still waiting for %i players to join %s with queue id %i", players_added, table_names[table_id], table_id + MSG_QUEUE_OFFSET);


    //THIS DOESN'T WORK!!!! IT DOESN'T WAKE UP
    if (msgrcv(msg_queue, &p, sizeof(player), table_id + MSG_QUEUE_OFFSET, 0) == -1)
    {
      logging_critical("recieving from message queue failed");
      _exit(1);
    }
    else
      logging_info("played joined %s", table_names[table_id]);

    logging_debug("player = %s, %s", p->name, p->password);

    players_added--;
  }

  logging_info("table %s ready to start!!!!!", table_names[table_id]);
}

void main_game_loop(void)
{
  logging_debug("main_game_loop");
}

      

        
        
        
      

    

It is assumed that the program is started and fork in 4 threads. The first three threads call msgget () to create the system's message queue.

Then they all call msgrcv () and wait for another identifier to appear.

The fourth thread listens for client connections and then calls msgsnd (). For some reason, none of the pending message forks will wake up again.

• I'm pretty sure the message queue is correct.

• I have a print statement before msgsrcv, so I can see that the fork runs correctly for each statement. After that the print expression also appears, so I can see that the code is not passing it.

• I ran ipcs from the command line.

• There is a specific message queue created and definitely has a message in it.

• If I change msgrcv to say "0" then one of the threads wakes up, but this is not the behavior I want.

• msgget () does not throw an error.

• msgsnd () did not throw an error.

• I'm pretty sure the ID in the structure is correct.

Any ideas what I am doing wrong?