how to share data/memory between mutiple JVMs ?

Thread view:

Enable EMail Alerts

Start New Thread

Jeff.C - 25 Jul 2006 08:46 GMT

Since JVM is a process of OS, is there any approach to share
data/memory between JVMs ?

Reply to this Message

Ingo R. Homann - 25 Jul 2006 11:12 GMT

Hi,

> Since JVM is a process of OS, is there any approach to share
> data/memory between JVMs ?

With standard-java there is AFAIK no possibility to share memory (on a
low level). But of course you can use Sockets, RMI, CORBA, a WebService,
or ... to let two applications "communicate" (exchange data) with each
other.

Hth,
Ingo

Reply to this Message

Jeff.C - 25 Jul 2006 16:35 GMT

I see your points.
I just wanna optimize a legacy muti-jvm ( muti-processes) system, in
which a lots of static data are stored in each process. and it will
consume lots of memory.
So RMI, Socket, ... is not suitable for access such lots of static
data.
If the jvm has a extension to create/access share memory, I believe it
will be a great feature.

Ingo R. Homann 寫道：

> Hi,
>
[quoted text clipped - 8 lines]
> Hth,
> Ingo

Reply to this Message

Jeff.C - 25 Jul 2006 16:44 GMT

Just an update,
As a new feature, JDK 1.5 can share read-only data between JVMs. :-)

Jeff.C 寫道：

> I see your points.
> I just wanna optimize a legacy muti-jvm ( muti-processes) system, in
[quoted text clipped - 19 lines]
> > Hth,
> > Ingo

Reply to this Message

Gordon Beaton - 25 Jul 2006 16:50 GMT

> If the jvm has a extension to create/access share memory, I believe
> it will be a great feature.

You won't find support for this in Java, but it's possible using
native code. Many years ago I implemented a Map that used SysV shared
memory as backing store, allowing multiple JVMs to share its contents.

/gordon

Signature

[ don't email me support questions or followups ]
g o r d o n + n e w s @ b a l d e r 1 3 . s e

Reply to this Message

Thomas Hawtin - 25 Jul 2006 17:30 GMT

>> If the jvm has a extension to create/access share memory, I believe
>> it will be a great feature.
>
> You won't find support for this in Java, but it's possible using
> native code. Many years ago I implemented a Map that used SysV shared
> memory as backing store, allowing multiple JVMs to share its contents.

You've been able to do this in Java for a number of years now...

http://download.java.net/jdk6/docs/api/java/nio/channels/FileChannel.html#map(ja
va.nio.channels.FileChannel.MapMode,
long, long)

Tom Hawtin

Signature

Unemployed English Java programmer
http://jroller.com/page/tackline/

Reply to this Message

Ingo R. Homann - 26 Jul 2006 07:36 GMT

Hi Jeff,

> I see your points.
> I just wanna optimize a legacy muti-jvm ( muti-processes) system, in
> which a lots of static data are stored in each process. and it will
> consume lots of memory.
> So RMI, Socket, ... is not suitable for access such lots of static
> data.

Why not? If the data is needed, it can be accessed cia the Socket.

Ciao,
Ingo

Reply to this Message

bob - 25 Jul 2006 18:54 GMT

> Since JVM is a process of OS, is there any approach to share
> data/memory between JVMs ?

Facets is a GemStone product that does this and more...
The Facets VM allows persisting any Java object transparently in a
repository that is accessed through a SharedMemoryCache. The Facets
system provides ACID transactions to manage updates to the shared
objects. It is scalable to hundreds of VMs concurrently accessing the
persistent data in the cache. It can also be configured to run in a
cluster of machines with a SharedMemoryCache on each machine.

For more information see: http://www.facetsodb.com

Reply to this Message

how to share data/memory between mutiple JVMs ?

Free Magazines