On 05/16/2011 02:36 AM, Charles Oliver Nutter wrote: > Can I get a rough guesstimate from the JVM guys how much more overhead > is involved in accessing a never-changed MutableCallSite versus a > ConstantCallSite? I have a few places where I want to use > invokedynamic to lazily initialize some literals. They'll never change > after the initial construction, but I can't create them in the > bootstrap because I need the state they pass in (e.g. the > org.jruby.Ruby instance they're associated with). I'd like to bind a > constant method handle into the site after the first call and never > change it again. > > - Charlie
Theoretically, the is no speed difference between a ConstantCallSite and a MutableCallSite that at some point never mutate. The difference is more that a MutableCallsite has to keep metada to trigger a de-optimization and not the ConstantCallSite. Now, practically, I don't know if hotspot make a difference between them. Charles, in your case you have two options: First, you are able to serialize the literal in the bytecode, the trick is that you can see an array of byte as a String, Terence Parr explains that 2 or 3 years ago at the JVM Summit. Second, if you know the org.jruby.Ruby instance when generating the code, you can cache it and look it up in the BSM. Rémi _______________________________________________ mlvm-dev mailing list mlvm-dev@openjdk.java.net http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
