codeigniter 2.1 $ this-> CI连续包含$ CI变量

$this->CI has $CI ($this->CI->CI)
And $this->CI->CI has $CI ($this->CI->CI->CI)
And $this->CI->CI->CI has $CI ($this->CI->CI->CI->CI)
And $this->CI->CI->CI->CI has $CI ($this->CI->CI->CI->CI->CI)
.....
......

$CI($this->CI->CI) has same keys and values with $this->CI (See following screenshot)

Image description

I can't determine how many $this->CI had $CI.

Why does $this->CI has $CI continuously?

Please tell me what the cause, what did I do something wrong?

There is no problem. $CI and $this are essentially the same memory location. The variables listing recusively lists the same memory structure again and again. The only way you will run out of memory is if you keep drilling down into the list and the debugger uses it all. In other words, what you a seeing is an illusion.