Java multi CPU capabilities

[William Muriithi]

> ps and top by default only show process not threads. There is opts to
show threads. In mono I have written program that showed many 100s threads
on a process and utilizing 4 cores.
>
Actually you are correct pstree. There even flags on PS to display the
threads.

That being said,  a default Java setup seem to trigger outage if the CPU
hit 100%. Since most of the system have 4 CPU that shouldnt be the case
till around 400%

Isn't this correct or am I wrong here too?
> Maybe there is some reason the hardware you are working on wants to be
super thread safe or something. I know gui are usually single threaded to
prevent a lot of foot shooting.
> I would guess Java has been able to do multi thread concurrent on
multicores for over 10 years. C# could and back then Java was more powerful
in just about every way over c#. Definitely not the case now however.
> .tl
>
Interesting, you are petty lucky then. I don't think that's happening in my
case and from what I can tell by extensive Googling, its a problem to a lot
of people.

Do you mind sharing the Java options you are using please?  I could play
around with it tomorrow and see what happen

William
> On Aug 28, 2013 8:03 PM, "William Muriithi" <william.muriithi-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org>
wrote:
>>
>>
>> > java is NOT the application.  It is the language and runtime for the
>> > application.
>> My bad. Agree, that a serious error on my side.
>>
>> >If an application wants to use multiple CPUs, then the
>> > author of the application should write a threaded application.
>> >
>> But how do you achieve that if your application is restricted without a
container that is only single kernel threaded?
>> > There is certainly research into making runtimes and languages that
>> > can automatically make some parts of the code run in parallel, but that
>> > isn't something you are likely to see in current production systems.
>> >
>> That seem to be the case
>>
>> > So if your application written in java creates multiple threads, then
>> > it will use multiple CPUs just fine.
>> >
>> Not necessary.  Sure, you can have as many threads as you want in the
container, but if that container just make a single kernel thread, you
wouldn't be able to sprend the thread across more than one CPU.
>>
>> That's what I am observing on both openjdk and sun Java.
>>
>> Casually check any server running Java based system and you will see the
whole application look like a single process to the operating system.  How
do you explain that?
>> > --
>> > Len Sorensen
>> > --
>> William
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