为什么设置php的session_set_cookie_params生存时间无效？

[ddp2010]

#login.php

define('SESSION_LIFE',1800);

session_set_cookie_params(SESSION_LIFE);
session_start();
$_SESSION['cookie'] = $user;


//打印session 参数
echo session_id().'<br>';
$arr = session_get_cookie_params();
print_r($arr);

----------------------------------------------------------------------------
55db8cbe4b2c5cafe6de3049a5887ff3
Array ( [lifetime] => 1800 [path] => / [domain] => [secure] => [httponly] => )
--------------------------------------------------------

#index.php

//打印session 参数
echo session_id().'<br>';
$arr = session_get_cookie_params();
print_r($arr);

55db8cbe4b2c5cafe6de3049a5887ff3
Array ( [lifetime] => 0 [path] => / [domain] => [secure] => [httponly] => )

-----------------------------------------------------------------------------

#PHP.INI

[Session]
; Handler used to store/retrieve data.
session.save_handler = files

session.use_cookies = 1

;session.cookie_secure =

; This option enables administrators to make their users invulnerable to
; attacks which involve passing session ids in URLs; defaults to 0.
; session.use_only_cookies = 1

; Name of the session (used as cookie name).
session.name = PHPSESSID

; Initialize session on request startup.
session.auto_start = 0

; Lifetime in seconds of cookie or, if 0, until browser is restarted.
session.cookie_lifetime = 0

; The path for which the cookie is valid.
session.cookie_path = /

; The domain for which the cookie is valid.
session.cookie_domain =

; Whether or not to add the httpOnly flag to the cookie, which makes it inaccessible to browser scripting languages such as JavaScript.
session.cookie_httponly =

session.gc_probability = 1
session.gc_divisor = 100

; After this number of seconds, stored data will be seen as 'garbage' and
; cleaned up by the garbage collection process.
session.gc_maxlifetime = 1440

[wpwppp]

session_destroy();

[ddp2010]

现在的问题是Session 一直有效，直到关闭浏览器或退出为止，设置的生存时间不起作用啊

[wpwppp]

[code=INIFile]
session.gc_probability = 1
session.gc_divisor = 100
[/code]
你要理解这两行的意思。
因为效率关系，PHP不会每次都去扫描SESSION是否过期，而是采用一个概率去决定，这两个参数设置，这个概率为1/100（百分之一）

[xiangzilhx]

3L说得对。"无效"只不过类似给session文件夹一个标记证明他无效了，但是不一定会删除。是有几率的，如果你把
session.gc_probability 设置成100 那就能删除了

[ddp2010]

谢谢大家，接分~