Question

Do I have the 64 bit of JDK installed on my machine?
My java -version says:
C:\Documents and Settings\Administrator>java -version

java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) 64-Bit Server VM (build 16.3-b01, mixed mode)

Should I expect a performance improvement in using a 64 bit compiler versus a 32 bit one?
Thanks,
Mike

Answer 1

Yes, it says Java Hotspot(TM) 64-bit. In regards to 64-bit vs. 32-bit JVM performance the main benefit of a 64-bit JVM is the larger address space. See the Hotspot FAQ.

The primary advantage of running Java
in a 64-bit environment is the larger
address space. This allows for a much
larger Java heap size and an increased
maximum number of Java Threads, which
is needed for certain kinds of large
or long-running applications. The
primary complication in doing such a
port is that the sizes of some native
data types are changed. Not
surprisingly the size of pointers is
increased to 64 bits. On Solaris and
most Unix platforms, the size of the C
language long is also increased to 64
bits. Any native code in the 32-bit
SDK implementation that relied on the
old sizes of these data types is
likely to require updating.