为什么Lua使用垃圾收集器而不是引用计数？ [英] Why does Lua use a garbage collector instead of reference counting?

问题描述

这是我发现的相关内容。

我自己听过并体验过它：Lua的垃圾收集器可以在游戏中导致严重的FPS下降。到垃圾收集器，在那里例如每创建一个Vector（）用户数据对象临时存在，直到收集垃圾。

我知道Python使用引用计数，这就是为什么它不需要像Luas GC那样的巨大的性能进食步骤。

• 为什么Lua不使用引用计数来获得摆脱垃圾？

解决方案

因为引用计数垃圾收集器很容易泄漏对象。 >

简单示例：一个双向链表。每个节点都有一个指向下一个节点的指针 - 本身指向下一个节点。如果你只是取消引用列表本身并期望它被收集，那么你只是泄露了整个列表 - 节点的 none 有一个引用计数为零，因此它们将互相保持对方活。使用引用计数垃圾收集器时，只要有循环对象，基本上都需要将其视为非托管对象，并在完成时自行处理。

<请注意，除了引用计数之外，Python还使用适当的垃圾收集器。

I've heard and experienced it myself: Lua's garbage collector can cause serious FPS drops in games as their scripted part grows.

This is as I found out related to the garbage collector, where for example every Vector() userdata object created temporarily lies around until getting garbage collected.

I know that Python uses reference counting, and that is why it doesn't need any huge, performance eating steps like Luas GC has to do.

• Why doesn't Lua use reference counting to get rid of garbage?

解决方案

Because reference counting garbage collectors can easily leak objects.

Trivial example: a doubly-linked list. Each node has a pointer to the next node - and is itself pointed to by the next one. If you just un-reference the list itself and expect it to be collected, you just leaked the entire list - none of the nodes have a reference count of zero, and hence they'll all keep each other alive. With a reference counting garbage collector, any time you have a cyclic object, you basically need to treat that as an unmanaged object and explicitly dispose of it yourself when you're finished.

Note that Python uses a proper garbage collector in addition to reference counting.

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