[stringtemplate-interest] it's 60% of time in ObjectModelAdaptor.getProperty()

[Oliver Zeigermann]

2011/2/6 Johan Stuyts <j.stuyts at javathinker.com>:
>> Yes, classes are garbage collected, but as they have a reference to
>> their class loader, they won't be garbage until the class loader is
>> garbage. Which can only be when you have created it. Or am I missing
>> anything here?
>
> I think you mean the other way around: the class loaders have a reference
> to their classes.

Right. Mixed that up.

> I am not familiar with the internals of class loaders, but if class
> loaders use normal references to their classes then this would of course
> prevent the classes from being collected. In that case you would need to
> use more class loaders to make sure old classes are unloaded. Although I
> feel that one class loader per class is a bit extreme. There must be other
> 'units' in StringTemplate to tie a class loader to.

Right. Like one per group maybe.

> I am fairly confident that class loaders don't hold on to their classes
> indefintely, but I am not 100% sure. A simple test can show how (custom)
> class loaders behave.

Talking about the default class loaders here I am almost 100% sure
they keep their classes forever. Otherwise static fields once
initialized might loose their values.

>> When dynamically loading classes from byte arrays I do not know of any
>> other way than creating your own class loader anyway.
>
> Me neither.
>
>> I sure know that
>> the - know to be picky - Google App Engine allows you to do so - as I
>> tried it :)
>
> Cool. And like I said: custom class loaders are common practice so most
> people won't have any problem with using them. But there might be
> enthousiastic StringTemplate users who have to deploy to more restricted
> environments. I guess these users would be disappointed if they cannot
> migrate to version 4 of StringTemplate because of the additional security
> restrictions. It's just something to keep in mind when the introduction of
> a custom class loader comes up.

Right. Compilation to JVM byte code should be optional.

- Oliver