Hi Andrea,

> On the fly compilation of classes will put the results in the permanent
> generation,
> depending on the garbage collector chosen it will result in a memory leak in
> the permanent generation (once put there there might be no way to reclaim
> them).
> This actually depends on what happens to the classloader that loaded the
> classes,
> not sure what the janino one does (like, does every compiled class have its
> own class loader that gets phased out after a while allowing the class
> bytecode
> to be garbage collected?), it needs some more investigation.

It provides a per-class classloader by default but you can specify an
alternative via the SimpleCompiler class (and probably in other ways).
So far with Jiffle I've just used the default mechanism. If you or
Simone ever use the Jiffle image operation I imagine this side of
things will get well tested and tweaked :)

> The other thing that I'm not sure about is type handling and conversions:
> much
> of the slowness in the current system is due to dynamic evaluation and
> type conversion, however that is also part of the expected behavior, like
> for
> example, if one of the data elements had a function that evaluates into a
> string, but I need a number, the current code would compensate via
> converters,
> what would the janino based code do?
> If it uses converters as well wouldn't we giving up much of the speedup?

I don't think I know enough about GeoTools' innards or the range of
use cases to provide any useful answer to that but for the restricted
case of raster rendering the converter issues are minimal or at least
well defined aren't they ?

Anyway, the IRC chat was nothing more than musing, inspired by the
dramatic difference that byte-code compilation made to Jiffle runtime
performance.

Michael

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