Trying to make some comparisons between Scala and Java. Using dynaTrace I can get very useful and granular insight into the behaviours of each. To keep things as comparable as possible the tests will be on simple, short algorithms. Large iterations will be conducted so garbage collection and space complexity can be analysed.
Thanks to Julio Faerman for his post and the implementations I have used from that post – see: http://www.infoq.com/articles/scala-java-myths-facts
With dynaTrace I can get information about the JVM behaviour but also about the behaviour of specific classes and methods. This will not only allow me to make some comparison between Java and Scala implementations but also understand more about what happens when Scala is compiled to byte code.
To start with, nice and simple test – Fibonacci sequence
Three implementations will be tested:
Java Fibonacci – see code
Scala Simple Fibonacci – see code
Scala Advanced Fibonacci – see code
I am running the tests from a controller class with a main method. From there I can instantiate the classes above. Read more about dynaTrace to see how it uses sensors in the JVM to grab a great deal of useful data about the JVM and about classes and methods.
Just to get things rolling, checked out how running the Fib sequence to the 10 million number in the sequence would affect the JVM. This tests would have taken a long time to complete so after I saw stable behaviour (ie: two sequences) I kill the JVM and moved on to the next sequence.
The charts below have been modified for human readability. For example, Garbage Collection in the charts was factored up. The charts are also stacked for readability. Within the dynaTrace client this is much easier to read with mouse over pop-ups.
What can be taken from this fairly simple example is that code may work and appear to be performing well. In reality it may be wreaking havoc on the JVM. Next post will look at the response times of these implementations.
Virtual Machine: Ubuntu 12.04 LTS 32 bit - 3072MB, 2 Processors
Physical Host: Windows 7 64-bit - 8GB, i7-2620M @ 2.70 GHz
java version "1.6.0_24" OpenJDK Runtime Environment (IcedTea6 1.11.1) (6b24-1.11.1-4ubuntu3) OpenJDK Server VM (build 20.0-b12, mixed mode)
Scala compiler version 2.9.2
#!/bin/bash scala_path=/usr/share/java/scala-library.jar java -Xmx2048m -cp $scala_path:. -agentpath:/home/mark/Desktop/performance_testing/dynatrace/agent/lib/libdtagent.so=name=TestJVM_scala_vs_java,server=192.168.242.60:9998 PerformanceController