Re: Millions of Threads ?

From:

Robert Klemme <shortcutter@googlemail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 28 Aug 2006 15:38:37 +0200

Message-ID:

<4lg9utF1oionU1@individual.net>

On 26.08.2006 01:38, frankgerlach@gmail.com wrote:

Hello folks,
I am thinking about a telecom application, which would potentially
handle millions of mobile
phones (J2ME) as clients. Of course, I need a server (J2SE), too.
The "easy" implementation uses TCP connections for the client/server
communication. Problem is that there are only 65000 sockets per IP
address of the server. I think I could solve that by configuring
multiple IP addresses per network card.
Still, two problems remain: Memory used by each TCP connection and by
the enormous number of threads (each client would have a server thread
for the "easy" implementation)
Because of all those issues I am considering the use of datagram
sockets and state machines (one per client) instead of one thread per
client. On the other hand, what is the difference between a state
machine called "Thread" and a "hand-crafted" state machine ? Both
consume memory, and maybe I could configure the JVM to allocate very
little memory per Thread.....
What do you think ? What is typically used in large telecoms
applications ?

Another option to deal with this is LWP (light weight processing
framework). You can find more info on this in Doug Lea's book [1]. The
basic pattern is that you have a thread pool and send requests down a
queue from which the first free thread picks the task processes it and
either sends results directly or through another queue where it is read
by one of another set of threads that transfers data back. You save the
overhead of thread creation and deletion at the cost of a minimal more
complex architecture.

Of course the basic precondition is that the system at hand has enough
resources (main mem, CPU cycles, IO bandwidth) to actually deal with the
load.

HTH

Kind regards

robert

[1] "Concurrent Programming in Java"
http://www.awprofessional.com/bookstore/product.asp?isbn=0201310090&rl=1
[2] Doug Lea's home page http://g.oswego.edu/