[Jython-dev] PyStringMap appears to be naughty

[Leo U. <leo...@ya...>]

I was looking at PyStringMap and it uses:
System.identityHashCode(a native method, yuck) as part
of its index calculation.  From my understanding,
Strings are generally interned in Jython, so it should
be cheap to call a hashCode on a particular String. 
According to the JDK String, its hashCode is
calculated once so after that it essentially is a
simple method call to access a variable.

Here is some output from a Test I put together that
compared the performance of hashCode vs
System.identityHashCode.
ONE: 106
TWO: 8
ONE: 117
TWO: 8
ONE: 115
TWO: 8
ONE: 116
TWO: 7
ONE: 116
TWO: 8
ONE: 115
TWO: 7
ONE: 115
TWO: 7
ONE: 115
TWO: 8
ONE: 114
TWO: 8
ONE: 115
TWO: 8


ONE is System.identityHashCode
TWO is hashCode
note, hashCode is called before the test/looping.  So
it seems that hashCode is about 16 times faster than
that identityHashCode.

I guess the question is, would it make sense to
investigate PyStringMap to see if it can be redone to
get more efficient indexing?(If possible)

leouser

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