A standard optimization is polymorphic inline caches (PIC). To support PICs for dynamic languages on the JVM, best practices recommend to build a tree-like structure at each active indy call site, where a (very limited) cascade of guard-with-test (GWT) MHs represents the spine of the cache.
It seems to me, however, that all this requires a lot of objects for each single indy site. Even granted that the JVM can beautifully inline the code of the specialized MHs like GWT MHs and bound-MHs (for the test), it still needs to maintain a large number of PIC trees. And PIC trees cannot usually be shared, since each call site has its own usage profile.
So, the question is whether some of you has experience with large scale projects written in a dynamic language implemented on the JVM, that makes heavy use of indy and PICs. I'm curious about the memory load for the PICs. I'm also interested whether the standard Oracle server JVM satisfactorily keeps up with the load.
For example, we have a large Smalltalk application with about 50'000 classes and about 600'000 methods. In Smalltalk, almost everything in code is a method invocation, including operators like +, <=, etc. I estimate some 5-10 millions method invocation sites. How many of them are active during a typical execution, I couldn't tell. But if the Smalltalk runtime were implemented on the JVM, PICs would quite certainly represent a formidable share of the memory footprint.
More generally, apart from toy examples, are there studies in real-world usage of indy and PICs in large applications? Perhaps some figures from the JRuby folks, or better, their users' applications would be interesting.
Thanks for numbers Raffaello Giulietti
smime.p7s
Description: S/MIME Cryptographic Signature
_______________________________________________ mlvm-dev mailing list mlvm-dev@openjdk.java.net http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
