[gclist] Sharing GC resources between applications

David Detlefs - Sun Microsystems Labs BOS david.detlefs at sun.com
Wed Mar 23 07:50:08 PST 2005

Kudos to David Bacon for his magesterial overview of the issues
surrounding this area!

I wanted to comment on only one small part of what he wrote.
Regarding the MVM/Isolates idea, he said:

  When isolates are implemented within a single process, they
  will probably use fewer resources, but will sacrifice another kind of
  isolation: fault isolation.  If one isolate does something that causes the
  JVM to fail, all other isolates will crash as well, which is a serious

I'm guessing that David would have no objection if I rewrote the end
of this to say:

  ...is a serious drawback today, when VM implementations have not yet
  reached the same level of maturity and reliability as operating
  systems.  In the long run, this approach essentially treats the VM
  *as* the operating system.  A program that panics the OS reveals a
  bug in the OS, not the program, no matter what the program did, and
  in the same way a program that crashes a VM reveals a bug in the VM.
  In the long run, the frequency of such bugs in VMs and OSs will
  become the same, at which point this argument against the Isolate
  approach no longer holds.

Reasonable people may, of course, differ on how long this will take :-)

Dave Detlefs                           http://www.sunlabs.com/people/detlefs/
Sun Microsystems Laboratories                           david.detlefs at sun.com
1 Network Drive, Burlington, MA 01803-0902                     (781)-442-0841

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