PHP/DOMDocument:unset()不释放资源 [英] PHP/DOMDocument: unset() does not release resources

问题描述

我有一个变量$dom，其中包含PHP的DOMDocument实例.正在循环中设置和取消设置此变量.

unset($dom)不会释放内存，但是:memory_get_usage(false)报告只有大约10MB的700B被释放. memory_get_usage(true)报告在unset()之前和之后的内存使用量完全相同.

我尝试了以下操作:

• 我检查了$ dom的引用计数是否恰好在调用unset()之前正好是一个:xdebug_debug_zval('dom')报告:dom:(refcount = 1，is_ref = 0)= class DOMDocument {}. /p>

• 我尝试了 DOMDocument PHP内存泄漏中提出的解决方案，但这是为了无济于事.

• 我尝试了gc_enable() + gc_collect_cycles().但这也无济于事.

• 我尝试在unset()之前调用$dom->__destruct()，但这会导致错误，因为DOMDocument显然没有析构函数.

• 在取消设置变量之前，我以递归方式删除了DOM中的所有节点.没什么区别.

• 在重新使用变量之前，我尝试将其设置为null:$dom = null

现在我没主意了……有人建议我还可以尝试调试或解决这个问题吗?

• php -v报告带有Suhosin-Patch(cli)的5.3.10-1ubuntu3.2

• 可在此处查看源代码: https://github.com/jerico-dev/ojs/blob/dev/plugins/generic/lucene/classes/SolrWebService.inc.php#L256

• 前几次迭代的输出为:

  before object creation: 19292296
  after object creation: 29849832
  before unset: 30055232
  after unset: 30054448
  before object creation: 29849592
  after object creation: 39858840
  before unset: 40079920
  after unset: 40079136
  before object creation: 39858272
  after object creation: 49923216
  before unset: 50136448
  after unset: 50135664
  

解决方案

这应该释放$ dom中的内存存储.

$dom = null;

I've got a variable $dom that contains an instance of PHP's DOMDocument. This variable is being set and unset within a loop.

unset($dom) will not release memory, though: memory_get_usage(false) reports that only 700B of about 10MB got released. memory_get_usage(true) reports the exact same amount of memory usage before and after unset().

I tried the following:

• I checked that the reference count of $dom is exactly one immediately before the call to unset(): xdebug_debug_zval('dom') reports: dom: (refcount=1, is_ref=0)=class DOMDocument { }.

• I tried the solution proposed in DOMDocument PHP Memory Leak but this was to no avail.

• I tried gc_enable() + gc_collect_cycles(). But this did not help either.

• I tried calling $dom->__destruct() before unset() but this will result in an error as DOMDocument apparently does not have a destructor.

• I recursively removed all nodes in the DOM before I unset the variable. It did not make the least difference.

• I tried setting the variable to null before re-using it: $dom = null

Now I'm out of ideas... Anybody got a suggestion what else I could try to debug or solve this problem?

Edit:

• php -v reports 5.3.10-1ubuntu3.2 with Suhosin-Patch (cli)

• The source code can be seen here: https://github.com/jerico-dev/ojs/blob/dev/plugins/generic/lucene/classes/SolrWebService.inc.php#L256

• The output of the first few iterations is:

  before object creation: 19292296
  after object creation: 29849832
  before unset: 30055232
  after unset: 30054448
  before object creation: 29849592
  after object creation: 39858840
  before unset: 40079920
  after unset: 40079136
  before object creation: 39858272
  after object creation: 49923216
  before unset: 50136448
  after unset: 50135664
  

解决方案

This should release the memory store in $dom.

$dom = null;

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