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How is the performance compared to straight Java? I know the Clojure on Android project is at the moment, slower due to the functional nature of the language.

by basil 17y ago

How is the performance compared to straight Java? I know the Clojure on Android project is at the moment, slower due to the functional nature of the language. Apparently the Dalvik garbage collector has to work overtime cleaning up because of the emphasis on creating new objects rather than mutating existing ones.

stefanrusek 17y ago
I have one app in the market that uses it and it runs great.
- mark_h 17y ago
  Cool! Which one, out of curiosity?
  - briancooley 17y ago
    This one, maybe? http://cn.androlib.com/android.developer.stefan-rusek-qpAq.aspx http://cn.androlib.com/android.developer.stefan-rusek-qpAq.a...
bad_user 17y ago
> I know the Clojure on Android project is at the moment, slower due to the functional nature of the language. There are two things that can hurt performance for functional languages on top of the Java VMs ... the lack of TCO and the mapping of a type-system that's too different to be mapped efficiently. In Clojure though what hurts is its dynamic nature, but you can go a long way by using type-annotations when you discover clear bottlenecks.
- plinkplonk 17y ago
  Is there any reason that the Dalvik VM shouldn't get TCO even if the JVM doesn't? I read somewhere that implementing TCO would necessitate a change in the bytcode and the jvm guys didnt ant to do this to break backward compatibility. N.B: I haven't investigated the Dalvik VM and/or the Android ecosystem in any great detail, so this might be afoolish question,but any answers appreciated.
stephenjudkins 17y ago
You can write Java-like code in Scala that compiles down to nearly identical bytecode to the Java version. If you're not using any primitives it will be 100% as fast. If you write idiomatic Scala code, or use many primitives in Java code, the performance of Scala becomes relatively worse. Every first-class function you use turns into the equivalent of a new class and object at runtime, and the immutable data structures are slower than their Java equivalents. I'm not sure how the performance delta differs between the JVM and Android's Dalvik VM. It may be that Dalvik's lack of JIT or less efficient garbage collector makes the Scala performance penalty bigger on Android. I would be interested in seeing some benchmarks.

by basil 17y ago

stefanrusek 17y ago

I have one app in the market that uses it and it runs great.

mark_h 17y ago
Cool! Which one, out of curiosity?
- briancooley 17y ago
  This one, maybe? http://cn.androlib.com/android.developer.stefan-rusek-qpAq.aspx http://cn.androlib.com/android.developer.stefan-rusek-qpAq.a...

bad_user 17y ago

> I know the Clojure on Android project is at the moment, slower due to the functional nature of the language. There are two things that can hurt performance for functional languages on top of the Java VMs ... the lack of TCO and the mapping of a type-system that's too different to be mapped efficiently. In Clojure though what hurts is its dynamic nature, but you can go a long way by using type-annotations when you discover clear bottlenecks.

plinkplonk 17y ago
Is there any reason that the Dalvik VM shouldn't get TCO even if the JVM doesn't? I read somewhere that implementing TCO would necessitate a change in the bytcode and the jvm guys didnt ant to do this to break backward compatibility. N.B: I haven't investigated the Dalvik VM and/or the Android ecosystem in any great detail, so this might be afoolish question,but any answers appreciated.

stephenjudkins 17y ago

You can write Java-like code in Scala that compiles down to nearly identical bytecode to the Java version. If you're not using any primitives it will be 100% as fast. If you write idiomatic Scala code, or use many primitives in Java code, the performance of Scala becomes relatively worse. Every first-class function you use turns into the equivalent of a new class and object at runtime, and the immutable data structures are slower than their Java equivalents. I'm not sure how the performance delta differs between the JVM and Android's Dalvik VM. It may be that Dalvik's lack of JIT or less efficient garbage collector makes the Scala performance penalty bigger on Android. I would be interested in seeing some benchmarks.