$model_mod = new Model_Base();
$model_mod->disconnect();
$pid = pcntl_fork();
//Both the parent process and the child process will execute the following code
if ($pid == -1) {
//Error handling: return -1 when failed to create a child process.
die('could not fork');
} else if ($pid) {
$model_mod->connect();
//The parent process will get the child process number, so here is the logic executed by the parent process
pcntl_wait($status); //Wait for the interruption of the child process to prevent the child process from becoming a zombie process.
} else {
//The $pid obtained by the child process is 0, so here is the logic executed by the child process.
}