Number of JVM's on Weblogic ?

altquark

altquark

Legendary Poster
Number of JVM\'s on Weblogic ?

After installing a few weblogic E1 servers - I realized that there is no specific way to create multiple JVM's except by creating multiple instances. This seems inefficient to me, the beauty of OAS and WAS was that multiple instances of the same JAS server could easily be created to utilize as much memory as you fed the machine - since each JAS was limited (through 32 bit) to 2Gb of memory.

Does anyone else have experience of this ? Perhaps I'm missing something, which someone can point to....!
 
Re: Number of JVM\'s on Weblogic ?

Jon,

I've just started dabbling with WLS, too, and noticed that it creates a JVM node id that shows as "singleton" in server manager. I don't see any easy way to increase the # of JVM's by just changing a number field, like I could on OAS. It definitely seems like a step backward to me.
 
Re: Number of JVM\'s on Weblogic ?

Don

Did you get your Admin Server to install through Server Manager ? That was a big difference to me, compared to starting through a freaking DOS window ! Theres a LOT of documentation required to get WLS up and running, all in different locations, and a lot of installation media that isn't combined in any single download.

I love the fact that Apache is delivered with WLS - but then Oracle states its "not suitable for production" and recommend installing THEIR web server using another 1Gb download to deliver it. Why not "bundle" THEIR web server WITH WLS in the first place ?

Oracle is basing their entire strategy with WLS - everything they've got is going to be running on WLS from Fusion to OBIEE to Governance. They really need to streamline the delivery format - which I'm certain they'll get a handle on. Eventually. But right now, coming from OAS and WAS, its frustrating to say the least !
 
Re: Number of JVM\'s on Weblogic ?

Correct me if I'm wrong, but isn't Oracle HTTP Server based on an older version of Apache (1.3 if I recall)?

And the fact that WebSphere is currently using IBM HTTP Server which is based on version 2.0 of Apache?

"Not ready for production" indeed ...
confused.gif
 
Re: Number of JVM\'s on Weblogic ?

Oracle HTTP Server included with Oracle Web Tier: "It is based on Apache 2.2.10..."

The web server bundled with WebLogic is only configurable up to a point.
 
Re: Number of JVM\'s on Weblogic ?

[ QUOTE ]
This seems inefficient to me, the beauty of OAS and WAS was that multiple instances of the same JAS server could easily be created to utilize as much memory as you fed the machine - since each JAS was limited (through 32 bit) to 2Gb of memory.

Does anyone else have experience of this ? Perhaps I'm missing something, which someone can point to....!

[/ QUOTE ]

Yes, that's it - One server supports one JVM, but you can add additional servers without installing an additional WebLogic server home.

Since only 64-bit JVMs are supported with E1 on WLS, at least now you have the option of scaling a JVM beyond 2GB. One of the recent tuning guides I've seen recommends very high arguments for the java heap min/max on JRockit. There's also language in the documentation which mentions "self tuning" of certain WebLogic server internals.

The most recent WLS install I performed was on IBM Power 7 hardware running AIX, for which Oracle doesn't supply a compatible JRockit - so we had to use the IBM 64-bit JDK. Haven't performed any testing yet.

A previous install on Windows 2008 R2 in a virtual machine with WLS 10.3.4 and the latest JRockit with java heap tuned beyond 2GB, and with Oracle Web Tier with both the Apache and Web Cache front ends configured, was the fastest E1 web client I've logged into.

The install prior to that, running on comparable hardware but Oracle Enterprise Linux 5, WLS 10.3.2 and the same JRockit version and tunables was close but not quite as "snappy" as the Windows installation I just mentioned.

Now wait until you see the default behavior of the JVM startup when starting from Server Manager (which uses the internal server JVM arguments) versus a Windows service or WLS startup script (you have to configure the JVM arguments in multiple places...and in the registry on Windows!)
 
Re: Number of JVM\'s on Weblogic ?

Thankyou Charles

Interesting perspectives. People have been telling me that they'd expect the linux to be faster than Windows 2008 - but so far, I've seen Windows 2008 to be pretty darn fast.

I did not know that someone had tuned above 2gb - is there an optimum limit ? If you have a link to that recent tuning guide, I'd much appreciate it. The fact that above 2gb is available does indeed negate the need for additional JVM's.

I'm very, very interested in hearing about the Power7 installation - my customer is also a Power7 install, but I have shied away from installing the WLS on there because of the lack of Jrockit availability on AIX - I am very unsure about putting WLS on the IBM JDK and how Oracle would support that configuration.
 
Re: Number of JVM\'s on Weblogic ?

Charles,

What happens when garbage collection occurs on memory allocations so large? My understanding is that the JVM essentially 'stops' until GC is complete, do I have this wrong?

Tom
 
Re: Number of JVM\'s on Weblogic ?

Plus I'm hearing that Java-64 is noticeably slower than Java-32...
 
Re: Number of JVM\'s on Weblogic ?

[ QUOTE ]
Charles,

What happens when garbage collection occurs on memory allocations so large? My understanding is that the JVM essentially 'stops' until GC is complete, do I have this wrong?

Tom

[/ QUOTE ]

This has been my understanding also, that the balance between large JVM's with a single, long GC and a smaller JVM with multiple, frequent GC is key to performance.
 
Re: Number of JVM\'s on Weblogic ?

Slightly old document by highly relevant information for this discussion - JRockit Tuning

Alex, on the iSeries the 64-bit JVM is slower than 32-bit JVM. Not true with WebLogic.

-Ethan
 
Re: Number of JVM\'s on Weblogic ?

Okay...I'm feeling obligated to chime in here.

In general terms ALL 64-bit JVM's are slower than their 32-bit counterpart. This is fact not fiction.

WLS is pretty much the same as WAS. WLS is simplier to administer from the console but WAS is way better on the scripting side.

I'm doing some testing with WLS on AIX on Power 7 with 5 GB JVM's. Yep that's right folks 5 GB JVMs. I've only recently done this to meet a requirement but it's likely that I'll be doing parallel GC's and a bunch of other things to limit the impacts of GC.

WLS is supported only on 64 bit so in theory you could create the JVM as large as possible. Now before anyone shoots me I think we all realize that a 100 GB JVM is bad for a whole lot of reasons.

For the clustering in WLS there are plenty of great whitepapers on the Support Site that are specific for JDE.


See the documents below on 64 bit vs. 32 bit JVMs.

http://www.oracle.com/technetwork/java/hotspotfaq-138619.html#64bit_performance

Scaling OSM 64-bit JVM on Multi-Core Based Servers [ID 1281365.1]

An Explanation Of Restrictions Limiting The Java Max Heap (-Xmx) To Around 1500M For 32bit JDK's On Microsoft Windows [ID 557813.1]

http://asserttrue.blogspot.com/2008/11/why-64-bit-java-is-slow.html
 
Re: Number of JVM\'s on Weblogic ?

I can send something to you if you've not found or received it already.

In regards to the Power7 install, I've advised the customer to perform an internal "bake off" of sorts between their new 770 hardware and commodity Intel hardware running Windows 2008 R2, all other software being the same with the exception of JRockit on the Windows server side.
It was their request to install WebLogic on the AIX servers, as they are currently running OAS on Sun and have had gotten used to managing the stack on UNIX, and generally speaking, the boxes just keep going and going...
 
Re: Number of JVM\'s on Weblogic ?

My statement wasn't meant to imply "better than 32-bit JVM" when speaking of the performance of the systems running 64-bit JVM. The fact that the systems were the fastest I've used have a lot more to do with brand new, screaming fast hardware, with lots of L2 cache, than with the performance characteristics of a 64-bit versus 32-bit JVM.

A decent explanation about 64-bit JVM performance can be read here:

http://asserttrue.blogspot.com/2008/11/why-64-bit-java-is-slow.html

There are many, many blogs and comments about this issue across the web, but since we're not able to run E1 with the 32-bit JVM on WebLogic, I suppose the matter is, at least for now, moot.

As far as GC frequency and pause times, a smaller JVM is going to cause more frequent full garbage collections, whereas a larger one will obviously decrease the frequency but increase pause times (time is relative to the smaller heap pause on the same hardware) as it scans the large heap. It's sometimes a customer specific tuning operation and depends on factors such as number of user, availability of server resources, uptime requirements, modules used...
 
Re: Number of JVM\'s on Weblogic ?

Your statement about ALL JVMs being slower 64-bit versus 32-bit, agreed. The key however, does the user notice? On the IBM i platform, it is not only measurable by us geeks but noticeable by the user. In some basic testing done with WLS a couple of years back (not with JDE), not so noticeable by the user. Yes, still measurable by the man behind the curtain but what the user perceives is ultimately what matters...

Just my two cents.

-Ethan
 
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