如果我有循环引用，是否可以触发PHP垃圾回收自动发生？

本文介绍了如果我有循环引用，是否可以触发PHP垃圾回收自动发生？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 我似乎想起了一种为类设置 __ destruct 的方法，它可以确保一旦外部对象立即清除循环引用超出范围。然而，我建立的简单测试似乎表明，这不是我预期/希望的行为。 有没有一种方法来设置我的类，以这种方式当最外层的对象超出范围时，PHP会正确地清理它们？ 我不想寻找替代方法来编写这段代码，我正在寻找是否这个可以做到，如果是的话，怎么样？我一般尽可能避免使用这些类型的循环引用。 class Bar { private $ foo; public function __construct（$ foo）{ $ this-> foo = $ foo; public function __destruct（）{ print[destroying bar] \\\; unset（$ this-> foo）; } } class Foo { private $ bar; public function __construct（）{ $ this-> bar = new Bar（$ this）; } public function __destruct（）{ print[destroying foo] \\\; unset（$ this-> bar）; 函数testGarbageCollection（）{ $ foo = new Foo（）; } （$ i = 0; $ i echo memory_get_usage（）。 \\\; testGarbageCollection（）; } 输出如下所示： 60440 61504 62036 62564 63092 63620 [销毁foo] [销毁条] [销毁foo] [销毁条] [销毁foo] [销毁条] [销毁foo] [销毁条] [销毁foo] [销毁条] 什么我曾希望： 60440 [destorying foo] [destorying bar] 60440 [destorying foo] [destorying bar] 60440 [destorying foo] [destorying bar] 60440 [destorying foo ] [destorying bar] 60440 [destorying foo] [destorying bar] 60440 [destorying foo] [destorying bar ] 更新： 有关PHP> 5.3的这个问题有几个很好的答案，但是我选择了适用于PHP的答案5.3，因为它实际上与我的项目（PHP 5.2.x）有关。 解决方案 只在对象被回收后才被调用，所以你不能使用它。虽然你可以创建一个手动清理功能： class Foo { private $ bar; public function __construct（）{ $ this-> bar = new Bar（$ this）; public function cleanup（）{ $ this-> bar = null; } public function __destruct（）{ print[destroying foo] \\\; } } class Bar { private $ foo; public function __construct（$ foo）{ $ this-> foo = $ foo; public function __destruct（）{ print[destroying bar] \\\; 函数testGarbageCollection（）{ $ foo = new Foo（）; $ foo-> cleanup（）; } 我不确定这是多么有用，但这是您唯一的选择< 5.3 I seem to recall a way to setup the __destruct for a class in such a way that it would ensure that circular references would be cleaned up as soon as the outside object falls out of scope. However, the simple test I built seems to indicate that this is not behaving as I had expected/hoped.Is there a way to setup my classes in such a way that PHP would clean them up correctly when the outermost object falls out of scope?I am not looking for alternate ways to write this code, I am looking for whether or not this can be done, and if so, how? I generally try to avoid these types of circular references where possible.class Bar { private $foo; public function __construct($foo) { $this->foo = $foo; } public function __destruct() { print "[destroying bar]\n"; unset($this->foo); }}class Foo { private $bar; public function __construct() { $this->bar = new Bar($this); } public function __destruct() { print "[destroying foo]\n"; unset($this->bar); }}function testGarbageCollection() { $foo = new Foo();}for ( $i = 0; $i < 25; $i++ ) { echo memory_get_usage() . "\n"; testGarbageCollection();}The output looks like this:604406150462036625646309263620 [ destroying foo ] [ destroying bar ] [ destroying foo ] [ destroying bar ] [ destroying foo ] [ destroying bar ] [ destroying foo ] [ destroying bar ] [ destroying foo ] [ destroying bar ]What I had hoped for:60440 [ destorying foo ] [ destorying bar ]60440 [ destorying foo ] [ destorying bar ]60440 [ destorying foo ] [ destorying bar ]60440 [ destorying foo ] [ destorying bar ]60440 [ destorying foo ] [ destorying bar ]60440 [ destorying foo ] [ destorying bar ]UPDATE:There are several great answers to this question relating to PHP > 5.3, but I selected the answer that would work with PHP < 5.3 since it actually relates to my project ( PHP 5.2.x ). 解决方案 As __destruct is only called once the object is being reclaimed, you can't use it for that. You can create a manual cleanup function though:class Foo { private $bar; public function __construct() { $this->bar = new Bar($this); } public function cleanup() { $this->bar = null; } public function __destruct() { print "[destroying foo]\n"; }}class Bar { private $foo; public function __construct($foo) { $this->foo = $foo; } public function __destruct() { print "[destroying bar]\n"; }}function testGarbageCollection() { $foo = new Foo(); $foo->cleanup();}I'm not sure how useful this is, but that's really your only option < 5.3 这篇关于如果我有循环引用，是否可以触发PHP垃圾回收自动发生？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！