PHP错误: Exception thrown without a stack frame in Unknown o

来自：网易博客 就目前我的了解，在两种情况下，PHP会报 Exception thrown without a stack frame in Unknown on line 0这种错误： 1）异常捕捉用了set_exception_handler导向,Exception里面执行另一个Exception 如下面这段代码，就会出现这种问题： http://

来自：网易博客

就目前我的了解，在两种情况下，PHP会报 Exception thrown without a stack frame in Unknown on line 0这种错误：

1）异常捕捉用了set_exception_handler导向,Exception里面执行另一个Exception

如下面这段代码，就会出现这种问题：

http://de.php.net/manual/de/function.set-exception-handler.php#88082

<span>function</span> error_handler(<span>$code</span>, <span>$message</span>, <span>$file</span>, <span>$line</span><span>)
{
    </span><span>if</span> (0 == <span>error_reporting</span><span>())
        </span><span>return</span><span>;
        
    </span><span>throw</span> <span>new</span> ErrorException(<span>$message</span>, 0, <span>$code</span>, <span>$file</span>, <span>$line</span><span>);
}
</span><span>function</span> exception_handler(<span>$e</span><span>)
{
    </span><span>//</span><span> ... normal exception stuff goes here</span>
    <span>print</span> <span>$undefined</span>; <span>//</span><span> This is the underlying problem</span>
<span>}
</span><span>set_error_handler</span>("error_handler"<span>);
</span><span>set_exception_handler</span>("exception_handler"<span>);
</span><span>throw</span> <span>new</span> <span>Exception</span>("Just invoking the exception handler");

exception_handler函数内print $undefined;这行本身会抛出一个异常，而他又去调用set_exception_handler的exception_handler函数，死循环了。

解决办法：不要在一个Exception里面执行另一个Exception

上面的问题可以用try ... catch的方式，如exception_handler改成下面这样：
 

<span>function</span> exception_handler(<span>$e</span><span>)
{
    </span><span>try</span><span>
    {
        </span><span>//</span><span> ... normal exception stuff goes here</span>
        <span>print</span> <span>$undefined</span>; <span>//</span><span> This is the underlying problem</span>
<span>    }
    </span><span>catch</span> (<span>Exception</span> <span>$e</span><span>)
    {
        </span><span>print</span> <span>get_class</span>(<span>$e</span>)." thrown within the exception handler. Message: ".<span>$e</span>->getMessage()." on line ".<span>$e</span>-><span>getLine();
    }
}</span>

2) 在析构函数抛出异常

参考这个bug:http://bugs.php.net/bug.php?id=33598

下面的代码就会报这个错误：

<span>class</span><span> test {
    </span><span>function</span><span> __construct() {
        </span><span>echo</span> "Construct\n"<span>;
    }

    </span><span>function</span><span> greet() {
        </span><span>echo</span> "Hello World\n"<span>;
    } 

    </span><span>function</span><span> __destruct() {
        </span><span>echo</span> "Destruct\n"<span>;
        </span><span>throw</span> <span>new</span> <span>Exception</span>( 'test'<span> );
    }
}

</span><span>$test</span> = <span>new</span><span> test();
</span><span>$test</span>->greet();

目前的解决办法：

1.不要在析构函数中抛出异常.

2.由于析构函数是在退出时执行的，所以要手动unset这种类，并catch该异常。

比如上面的例子，在最后加一行unset($test),这时程序就会报throw new Exception( 'test' ); 这行有错误，再catch这个异常就行了。

上面两种情况在php 5.2.11版本上都会出现，至于原因我认为PHP可能就是这样处理的，php bug 33598 2005年就报上去了，bug Status为Closed，说明官方并不认为这是一个bug,或不当一个bug处理了。