Hotspot at Last

ohshima at ohshima at
Wed Apr 28 12:57:27 UTC 1999


> I did find the following bullet points in the white paper very 
> amusing.  It appears that Sun has discovered that the following 
> tricks, in addition to its admittedly way-cool dynamic profiling and 
> adaptive optimizing, can lead to improved peformance in a VM:
> 	(*) Handle-less pointers;
> 	(*) Shorter (two-word) object handles;

  I found there is a sentense on the white paper: "only
arrays have a third header field, for the array size."

> 	(*) Generational, copying compacting garbage collection, 
> which they repeatedly characterize as "pauseless;" and

   The algorithm is also called as "mark-compact algorithm".

  More and more I read the white paper, it reminds me the
design and implementation of Squeak (and Self, of course).

> 	(*) Reflective Data (Classes, MetaClasses and Methods) are 
> now represented as first-class objects to facilitate a simpler object 
> memory model and faster garbage collection.

  I think the biggest difference is the way for management
of "Contexts."  HotSpot VM uses native machine's stack for
the performance and possible parallel execution, though it
may be the source of memory leaks:-)

                                             OHSHIMA Yoshiki
                Dept. of Mathematical and Computing Sciences
                               Tokyo Institute of Technology 

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