# SessionHandler::gc

(PHP 5 >= 5.4.0, PHP 7, PHP 8)

SessionHandler::gc — Cleanup old sessions

### 说明

public SessionHandler::gc(int `$max_lifetime`): int|false

Cleans up expired sessions. Called randomly by PHP internally when a session starts or when session_start() is invoked. The frequency this is called is based on the session.gc_divisor and session.gc_probability configuration directives.

This method wraps the internal PHP save handler defined in the session.save_handler ini setting that was set before this handler was set by session_set_save_handler().

If this class is extended by inheritance, calling the parent `gc` method will invoke the wrapper for this method and therefore invoke the associated internal callback. This allows this method to be overridden and or intercepted and filtered.

For more information on what this method is expected to do, please refer to the documentation at SessionHandlerInterface::gc().

### 参数

`max_lifetime`

  Sessions that have not updated for the last `max_lifetime` seconds will be removed.

### 返回值

Returns the number of deleted sessions on success, 或者在失败时返回 `false`. Note this value is returned internally to PHP for processing.

### 更新日志

版本 | 说明
--- | ---
7.1.0 | Prior to this version, the function returned `true` on success.

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