问题
Is there a way to force garbage collection in VBA/Excel 2000?
This question refers to the Macro language in Excel. Not using VB .NET to manipulate Excel. So GC.collect() won't work
回答1:
You cannot take advantage of garbage collection provided by the .NET Framework when using straight VBA. Perhaps this article by Eric Lippert will be helpful
回答2:
You can't force GC in VBA, but it's good to set to Nothing the global variables.
The article mentioned by kd7 says it's useless to set to Nothing the local variables before they go out of scope, but doesn't talk about the global variables.
In VBA the global variables defined in a module remain alive through the whole Excel session, i.e. until the document containing the VBA module that defines them closed.
So don't put useless Set O = Nothing when O is local, but do it when it's global.
回答3:
VBA/Excel does not have garbage collection, like old VB. Instead of GC, it uses reference counting. Memory is freed when you set a pointer to nothing (or when variable goes out of scope). Like in old VB it means that circular references are never freed.
来源：https://stackoverflow.com/questions/1775470/forcing-garbage-collection