Benchmarking Smalltalk on JVM

[Mark Roos]

I just loaded about 250K lines of Smalltalk code into my jvm 
implementation so now I can start
some real benchmarks using our application.  All of this was done on a 
Mac.

My first try was a object load which takes about 20 files and creates a 
pretty complex object set.  This
takes 100 seconds in ST and using the initial jdk7 release I also get 100 
seconds.  Not bad.  But 
I see that one of the major slowdowns is in my use of boxed integers vs 
STs use of Fixnums.  So
I did some more detailed experiments.

Using this code snippet which creates and drops about 2 million Integers 
which ST does in about 10ms.

    | bytes pos sum |
    bytes := ByteArray new:1000000.
    sum := 0.
    pos := 1.
    [pos <= 1000000]    whileTrue:[
        sum := bytes at:pos.
        pos := pos + 1].
    ^sum

For the initial JDK7 I get 400ms,  moving to jdk8 b20 it drops to 117ms ( 
very nice).
I then converted some constructor lookups to statics to get to 66ms.
Then the obvious move to make an integer cache for which I used the jTalk 
range of -2000 to 4000 gave 30ms
And finally ( to handle the index integer) I created a MutableInteger 
which dropped me to 5ms.

So 2X better than the ST I started with.

But then I upgraded to jsk8b23 and now the best I see is 16ms.  It also 
seems like the jit sometimes 
compiles and sometimes not even using the same startup sequence.  Bleeding 
edge I would guess.

But for the final test I used jdk7u4 and my load is 73 seconds.  Not as 
good as the best jdk8b20 ( 60 seconds)
but faster than native Smalltalk

looking good
mark
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