Java multi CPU capabilities

[ted leslie]

I know c# (ms, or mono), have concurrent garbage collection, so in
this sense c# has some multiple processing running below it,
I assume Java would too. There are many things in a CIL runtime  or
java JVM that can be concurrent, and I think where they get
the best bang for the buck  they do it. But they obviously have to
worry about breaking legacy apps, in that the legacy app. may have
a bug but it never gets exploited because the VM has done it serial,
now its trying it concurrent.
Plus, aside from concurrent GC, you will not get much more improvement
really, as with java or c# you are generating close to the
assembly/binary you do with C/C++, in some cases you are actually
generating even faster code then c/c++, and you don't run c/c++ on
"more then one cpu"(as its not a lang vm) unless you program it or use
libs that do.
So I guess, aside from rephrasing your question to be, why does Java
not use more then one CPU for GC, I can only speak for c#,
where it DOES, but I would have to say Java does to? if they don't,
that's a shame.

You could say the same type of question for : why doesn't C/C++ lib
XYZ do more stuff concurrently (of course some do), or why
X11/gnome/KDE
doesn't do more concurrently ..... they should, but in many cases its
old legacy stuff, with concurrency improvements bring about new bugs,
and
like gnome/kde etc doesn't have enough of those? :)

For small tasks, sometimes one arch. may allow concurrent to be
faster, another, its faster serialized. Or its faster if spread over 2
concurrent
jobs, but divide it to 8, and its slower then if divided to 2.
Raytracing, for example, a super concurrent able job, if you had a cpu
with 1M+ cores, you would think it would raytrace well,
but the overhead (on existing tech.) to assign all those jobs, then
memory contention .... so it may be better with 256 cores.
Its all very tricky stuff, especially when intel/amd/nvidia etc are
improving on multicore tech currently.

-tl

On Tue, Aug 27, 2013 at 9:48 PM, William Muriithi
<william.muriithi-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> Evening,
>
> Just curious if anyone here has ever looked at getting Java to run on more
> than one CPU.
>
> I have looked around and concluded that's not possible natively.  Posting
> more or less for confirmation. Would I have missed anything?
>
> Found it an odd problem for a application to have at this time, really its
> 2013
>
> http://www.datadisk.co.uk/html_docs/java_app/jboss5/jboss5_tuning.htm
>
> Came across this and petty the best article I have seen about Java.
>
> Good evening.
>
> William
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