Function RM_Fork

app/redis-6.2.6/src/module.c:7861–7876

Create a background child process with the current frozen snaphost of the * main process where you can do some processing in the background without * affecting / freezing the traffic and no need for threads and GIL locking. * Note that Redis allows for only one concurrent fork. * When the child wants to exit, it should call RedisModule_ExitFromChild. * If the parent wants to kill the child it

 * of the child, and the child process will get 0.
 */
int RM_Fork(RedisModuleForkDoneHandler cb, void *user_data) {
    pid_t childpid;

    if ((childpid = redisFork(CHILD_TYPE_MODULE)) == 0) {
        /* Child */
        redisSetProcTitle("redis-module-fork");
    } else if (childpid == -1) {
        serverLog(LL_WARNING,"Can't fork for module: %s", strerror(errno));
    } else {
        /* Parent */
        moduleForkInfo.done_handler = cb;
        moduleForkInfo.done_handler_user_data = user_data;
        serverLog(LL_VERBOSE, "Module fork started pid: %ld ", (long) childpid);
    }
    return childpid;
}

/* The module is advised to call this function from the fork child once in a while,
 * so that it can report progress and COW memory to the parent which will be