Unset the parser after calling xml_parser_free() to prevent memory leaks:
<?php
xml_parser_free($parser);
unset($parser);
?>
xml_parser_free
(PHP 4, PHP 5, PHP 7, PHP 8)
xml_parser_free — 释放 XML 解析器
说明
注意:
此函数无效。在 PHP 8.0.0 之前，用于关闭资源。
释放指定 XML parser。
警告
除了在解析完成时调用 xml_parser_free() 之外，在 PHP 8.0.0 之前，如果 parser
资源引用自对象，且对象引用 parser 资源，还必须明确取消对 parser 的引用以避免内存泄漏。
参数
-
parser - 指向要释放的 XML 解析器的指针。
返回值
成功时返回 true， 或者在失败时返回 false。
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User Contributed Notes 3 notes
nidzho ¶
8 years ago
dio at edu dot uni-klu dot ac dot at ¶
19 years ago
If you try to free an XML parser while it is still parsing, strange things will happen - your script will "hang" and no output will be sent to the browser. Consider this pseudo-code example:
-------
...
if (!xml_parse($parser)) echo 'XML error';
xml_parser_free($parser);
...
function SomeCallbackWhichWasSetBefore(...)
{
global $parser;
...
if (some_error_happened) xml_parser_free($parser); //problem!
...
}
------
It would be logical that xml_parse would return false if the parser was freed while parsing, right? Wrong! Instead, everything hangs and no output will be sent out (no matter whether output buffering is on or not). It took me more than an hour to figure out why: you cannot free a parser handle that is currently parsing. A simple solution:
-------
$xml_error = false;
if (!xml_parse($parser))
echo 'XML error (directly from parser)';
else if ($xml_error)
echo 'XML error (from some callback function);
xml_parser_free($parser);
...
function SomeCallbackWhichWasSetBefore(...)
{
global $parser;
global $xml_error;
if ($xml_error)
return;
...
if (some_error_occured)
{
$xml_error = false;
return;
}
...
}
-------
If you use this solution you will have to check for $xml_error in every callback function. Essentially what you're doing is that, in case you want to stop parsing because of an error, you continue until xml_parse() is finished (without actually doing anything) and then free the parser and act on the error.
Of course the underlying problem is that you cannot stop a parser while it is parsing. There should be some function like xml_throw_error() or xml_parser_stop() or whatever, but unfortunately there isn't.
php dot net at gwprogramming dot com (George Webb) ¶
21 years ago
I found that with PHP 4.3.4RC1, if you don't call xml_parser_free() before your script ends, some sort of ugliness occurs with the webserver; i.e. the HTTP connection is closed. (The apache error_log says "exit signal Segmentation fault (11)".)
Usually PHP tends to clean up connections you don't explicitly close (e.g. database connections), but in this case apparently it doesn't.
Some web browsers (MSIE for one) do not actually show this problem, so you may not actually notice it. Opera 7.11 does show it, which is how I discovered it.
So don't forget to call xml_parser_free() ... always!
