Why do php redis get data returns with colons

The problem

I wrote a multi-threaded implementation of the code and tried to use redis as a counter, this is my code. When I try to use redis as a counter, I often get ‘:'(colon) in the value, sometimes not, is it because I loop too fast and redis doesn’t even notice?

Output result

cclilshy@192 debug % php st.php
registerRedis success!
registerSocket success!
1
2
3
1
2
string(2) ":5"
1
2
3
string(2) ":9"
3
string(1) "9"

// the up is the output. Why?

Code

$func = function($handle){
    for($i=0;$i<3;$i++){
        echo $handle->counter().PHP_EOL;
    }

    var_dump($handle->total());
};

//$handle->counter() :
public function counter($record = true){
        if($record = false){
            return $this->count;
        }
        $this->thread->counter();
        $this->count++;
        return $this->count;
}

//$handle->total() :
public function total(){
        return $this->thread->counter(false);
}

//$handle->thread->counter() : 
public function counter($record = true){
        if($record === false){
            return $this->redis->get('thread.' . $this->pids[0] . '.count');
        }
        return $this->redis->incr('thread.' . $this->pids[0] . '.count');
}