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From Nathan Schrenk <>
Subject Re: project plan
Date Tue, 16 Jul 1996 02:14:22 GMT

On Mon, 15 Jul 1996, Robert S. Thau wrote:

> Since it may not be entirely common knowledge, I probably should have
> pointed out explicitly that Sun's own Java VM implementation does not
> use native threads even on Solaris (Sun's own system, which supports
> them), but instead uses a user-mode thread package which the Java team
> wrote on their own, called "green threads".

However, Sun's port of Java to WinNT uses native NT threads.  I have seen
mention on a mailing list somewhere by a Sun employee that there are plans
to switch the Solaris implementation of Java to native thread support 
sometime in the future. 

> I've never heard an authoritative statement of exactly *why* they did
> this.  The most common third-hand rumor is that with Solaris native
> threads (which was the first thing they tried), they had real trouble
> getting all of the Java threads to reliably suspend themselves when
> they wanted to do a garbage collection.

I've heard something similar about them getting all the threads to stop
while garbage collection occurs.  The following snippet of a (very old)
message on the java-porting mailing list indicates that implementing a
Java VM with native threads is actually not as bad as one might think.
(This document can be found at

Tim Lindholm (lindholm@scndprsn.Eng.Sun.COM) wrote:


One thing that the one-platform-only alpha3 source release obscures is
that porting Java's threads and synchronization to a platform that's got
native threads is much easier than the current Solaris release might
suggest. Keep in mind that the current release implements its own
preemptive threads! The Win32 system is much simpler, using the native
facilities and far less code. Another approach to better portability will
be through the pthreads ports that are happening (SunOS, Linux and
others). If you can assume a good pthreads package (and many platforms
can), the Java runtime would be portable and its sources simple. 



Nathan Schrenk
Neoglyphics Media Corp.                    

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