xushijie · January 1, 2016 16:58 · xushijie · Dec 29, 2013
diff --git a/gistfile1.txt b/gistfile1.txt
 They use various metrics to characterize the dynamic behavior of a variety of programs written in three dynamic languages (Clojure, Python, and Ruby) executing on the JVM. 

 We have previously presented a comprehensive toolchain [20] for workload characterization across JVM languages2, which was successfully applied in studying the differences. 

 The metrics are: 
 Call-site Polymorphism. 
   Hints at opportunities for optimizations at polymorphic call-sites, e.g. inline caching [13] (based on the number of receiver types), or method inlining [10] (based on the number of target methods).  => On average, 98% call site only has one targte method.

 Field, Object, and Class Immutability. 
  Enables load elimination [3] (replacing repeated accessess to immutable objects with an access to a compiler-generated temporary stored in a register), and identifies objects and side-effectfree data structures amenable to parallelization.

 Object Lifetimes.
   Determines garbage-collector (GC) workload,and aids in design and evaluation of new GC algorithms, e.g. the lifetime-aware GC [15].

 Unnecessary Zeroing. 
   Hints at opportunities for eliminating unnecessary zeroing of memory for newly allocated objects, which comes with a performance penalty [25].

 Identity Hash-code Usage. 
     Hints at opportunities for reducing header size for objects that never need to store their identity hash code (often derived from their memory location upon first request [1]).
	They use various metrics to characterize the dynamic behavior of a variety of programs written in three dynamic languages (Clojure, Python, and Ruby) executing on the JVM.

	We have previously presented a comprehensive toolchain [20] for workload characterization across JVM languages2, which was successfully applied in studying the differences.

	The metrics are:
	Call-site Polymorphism.
	Hints at opportunities for optimizations at polymorphic call-sites, e.g. inline caching [13] (based on the number of receiver types), or method inlining [10] (based on the number of target methods). => On average, 98% call site only has one targte method.

	Field, Object, and Class Immutability.
	Enables load elimination [3] (replacing repeated accessess to immutable objects with an access to a compiler-generated temporary stored in a register), and identifies objects and side-effectfree data structures amenable to parallelization.

	Object Lifetimes.
	Determines garbage-collector (GC) workload,and aids in design and evaluation of new GC algorithms, e.g. the lifetime-aware GC [15].

	Unnecessary Zeroing.
	Hints at opportunities for eliminating unnecessary zeroing of memory for newly allocated objects, which comes with a performance penalty [25].

	Identity Hash-code Usage.
	Hints at opportunities for reducing header size for objects that never need to store their identity hash code (often derived from their memory location upon first request [1]).