Here is the promised article by about

Question

Here is the promised article by < Iaroslav Postovalov> about AST based optimization of kmath expressions during runtime

Ilya Muradyan · Answer

Looks great Is it possible to get a working Class lt gt instance by giving it an expression string I d like to try it out Some points 1 You may try to generate primitive versions of Expression and Algebra Instead of using generics interfaces to avoid boxing issues and performance regression 2 Operations seem to fit enum type naturally You won t need using string identifiers and map lookup just define enum with appropriate methods Also it would be great to see more detailed performance analysis with different optimisations enabled and with different sizes of expressions

altavir · Answer

I believe < Iaroslav Postovalov> did all that he can address the question There are benchmarks in the repository as well

altavir · Answer

An important thing that I expected and < Iaroslav Postovalov> confirmed is that JIT is almost as effective as byte code generation when all types are known in advance and we do not generate nested functions

Iaroslav Postovalov · Answer

< Ilya Muradyan> hello we actually get class object and provide its instance to the user

Iaroslav Postovalov · Answer

< Ilya Muradyan> boxing issue is partially optimized by inserting calls to primitive methods not to bridge methods so only the return value is being boxed It s nice idea to create specialized methods for double int long

Iaroslav Postovalov · Answer

< Ilya Muradyan> I m not good in building complex performance comparisons and distributions

Iaroslav Postovalov · Answer

< Ilya Muradyan> string operations IDs are designed at core module however it s possible to replace methodNameAdapters with enum thanks for advice

Ilya Muradyan · Answer

Thank you for answers One more q how many arguments map access operations will be performed for expression x x x One or three

altavir · Answer

I believe that it will be a tree with 3 nodex each of those use 2 argument primitive operation In AST the tree will be traversed and flattened

Iaroslav Postovalov · Answer

I think 3

Iaroslav Postovalov · Answer

Thanks for idea of optimization

Iaroslav Postovalov · Answer

< Ilya Muradyan> but there is a possible problem map can be mutable or return random values

Iaroslav Postovalov · Answer

I don t want to make complicated contract for input map

Ilya Muradyan · Answer

Different values for the same key This contract seems to be natural but I agree there could the cases

Iaroslav Postovalov · Answer

Yes Optimizations like this must be opt in and during profiling I didn t noticed any problems because of HashMap get

altavir · Answer

HashMap get is super optimized on JVM so the access cost is close to the array access It should be profiled of course

Iaroslav Postovalov · Answer

I ll review x x x expression

altavir · Answer

The MST interpretter actually allows caching the value of the variable But I do not think it is relevant right now