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From "Preston L. Bannister" <pres...@bannister.us>
Subject Re: Challenges for Java hosting
Date Thu, 06 Apr 2006 19:20:53 GMT
Define "lightweight". :)

If we are talking about a small number of users, with high average
utilization, this might be a good solution.  In fact this is similar in
resource usage to the virtual hosting (i.e. Xen) solutions.

For more typical usage, the number of users is large, and the average
utilization is low.  In this case one (very rarely used) JVM per user is
somewhat expensive.

Note you could reduce the expense with the same approach of using a fork()
of a single image, expecting copy-on-write to radically reduce the real
memory use (virtual memory use would be larger).

Depends on what target you are trying to hit.  The hosting world (by numbers
of users) is dominated by very low usage sites.  Is this a goal for
Java/Tomcat hosting?  If you can beat PHP in CGI mode *both* in performance
and in resource usage, then you have a pretty compelling solution.  If you
are fatter or slower - this is going to disinterest a lot of hosting
providers.

Note that this notion is pretty much a non-starter if Linux does not do
copy-on-write with fork().  This was a big deal back in the late 1980's (big
Lisp apps forking "vi").  Don't know if this made it's way into Linux.  I'm
pretty sure copy-on-write in fork() was in SunOS, but I don't know about
Solaris.


On 4/6/06, Leon Rosenberg <rosenberg.leon@googlemail.com> wrote:
>
> isn't it easier to give each user a pre-configured lightweight but own
> tomcat?
>
> leon
>
> On 4/6/06, Preston L. Bannister <preston@bannister.us> wrote:
> > Well, that is one definition of "real applications".   There are other
> > definitions.  :)
> >
> >
> > On 4/6/06, Tino Schwarze <tino.schwarze@tisc.de> wrote:
> > >
> > > On Thu, Apr 06, 2006 at 09:15:17AM -0700, Preston L. Bannister wrote:
> > >
> > > > You have to consider how (or if) to allow for long-running
> background
> > > > threads.  Successive requests for the same user will not use the JVM
> > > > (whether this counts as an advantage or disadvantage is
> debatable).  The
> > > JVM
> > > > isn't going to be optimizing code.
> > >
> > > The point of using an application server (instead of e.g. PHP) is that
> > > it maintains state on the server. You lose this by using fork(). So
> it's
> > > not going to work at all for real applications since your application
> > > "returns" to it's previous state after every request.
> > >
> > > Bye, Tino.
> > >
> > >
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> > >
> > >
> >
> >
>
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>

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