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I have heard that some JVMs are significantly faster than others. Especially HotSpot is told to be very fast.

But which JVM do I already use?

$ java -version
java version "1.6.0_20"
OpenJDK Runtime Environment (IcedTea6 1.9.13) (6b20-1.9.13-0ubuntu1~10.04.1)
OpenJDK Server VM (build 19.0-b09, mixed mode)

Which JVM get used in the free official download?

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up vote 0 down vote accepted

You are using the IcedTea build of the OpenJDK JRE, which is based mostly on the same code base used by the "official" version from Oracle.

  • Put simply, you are using the IcedTea JVM.
  • Hotspot is provided by the "official" download
  • But IcedTea is based on Hotspot! (see their homepage for details)
    • The only difference is that IcedTea has a separate (open-source) browser plugin!
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