Hello!
I haven't dug deep enough to say anything authoritative, but I think
you've the got the thread memory and shared memory sort of backwards.
To my understanding, "shared memory" generally means that the data is in
the Main memory (RAM) of the computer
(see http://en.wikipedia.org/wiki/Memory_(computers) )
where it can be accessed by every CPU. In contrast, "thread working
memory" does not need to accessible by other CPUs, so the java runtime
will make every effort to perform "thread working memory" instructions
in the CPU registries and cache.
(see http://en.wikipedia.org/wiki/Processor_register )
Copying between the CPU local memory and main memory is still
unavoidable if the data is too big to fit to what the CPU has. If you
still want to build something on top of java threads then I suggest you
read on user threads or "fibers".
-Eero Nevalainen
Steve Ulrich wrote:
Hi!
I don't think mina-list is the right list for this.
Some thoughts, anyway:
"shared memory" between threads should be synchronized somehow (doesn't mean it has to be
in a synchronized block), so it's a big performance killer to synchronize all variables. If you
need synchronized variables read the documentation for the "volatile" flag and the API
for the atomic- and concurrency-packages will be usefull as well.
If you implement your own "thread model" in a single thread, your application won't scale very well
to multi processor systems. A simple form of this "thread model" is the Executor created by
"Executors.newSingleThreadExecutor()". But it's poison for scalability!!!
My opinion: using some volatile flags, Locks and concurrency collections at the right
positions will surely do the trick and lead to a better scalability. Even a little
oversynchronisation will be better than a "single thread thread model" ;-)
regards
Steve
Simon Funnell [mailto:[EMAIL PROTECTED] wrote:
Dear List,
This is not exactly Mina specific, its more general, but its close to
the problem Mina surrounds. I have been working on an approach to
concurrency and I have come to the point where the Java Thread model is
causing me problems. I would like to create my own threading model that
does away with shared memory and thread memory, so there is just shared
memory. My original idea was to use a single thread and implement my
own
threads within that thread. The difficulty with this is that there is
still copying from shared memory to thread working memory (as I
understand it). I would like to cut out this shared memory to thread
memory and back to shared memory copying. Is this possible?
Thanks for any replies.
Regards,
Simon
