Hotspot at Last

Andrew C. Greenberg werdna at gate.net
Wed Apr 28 00:38:32 UTC 1999


Sun announced the actual, really, truly, gonna-do-it-this-time, 
really, uh-huh, not-kidding-at-all, this-is-it release of Hotspot, at 
last.  Well, sort of.  (Binaries will be around "later this week" for 
some platforms)

But the press release, white paper and data sheet, those are ready 
for downloading right now, and they are available in fully 
human-readable open-source English!  (Impressive, since the 
announcement was made in Paris.)

<Tongue surgically removed from cheek>

All kidding aside, it will be nice to see a serious, commercial 
dynamic optimization finally hit the decks.  Unsurprisingly, Sun is 
already downplaying expectations, suggesting that Hotspot will be 
more significant on the server side than the client side, at least on 
the first release.  (Quite true, since the server is likely to stay 
"warm" longer.)

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;

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

	<<YOU GOTTA LOVE THIS!>>

	(*) 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 also thought these ideas were pretty cool . . . when I read about 
them in "Back to the Future."





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