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| javaw.exe and CPU consumption |
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| goffinf |
 Posted: Tue Mar 17, 2009 1:31 am Post subject: javaw.exe and CPU consumption |
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Chevalier
Joined: 05 Nov 2005
Posts: 401
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WBIMB version: 6.1.0.3
Toolkit version : 6.1.0.3 (iFix002)
Platform: Windows XP
Memory: 1.5GB
Page File Size: Typically 2GB (but I have tried it with 0 - not much difference and occasion 'Out of Virtual Memory')
I know this has been brought up before and I have read most of the posts, but we're still experiencing a major problem with javaw.exe using 90-100% of the CPU.
I wondered whether there is any new advice that relates to using 6.1 (new version of eClipse and Java).
The behaviour is not that CPU is maxed-out for long periods, it mostly lasts for a few seconds (5-10) but is occuring all of the time whilst the MB toolkit is open and you're going about typical activities (switching perspectives, editing eSQL, building flows, ... usual stuff). This obviously makes development both slow and very frustrating.
I have tried all kinds of combinations of vmargs for the toolkit short-cut, most recently I use :-
-vmargs -Xms256M -Xmx512M -XX:PermSize=64M -XX:MaxPermSize=128M
I have also tried -XX:+UseParallelGC and -Dosgi.requiredJavaVersion=1.5
none seem to have much effect.
I note that the eclipse.ini file in C:\Program Files\IBM\WMBT610 contains these settings, so it may be that these are the ones that are actually in use. In any event they are largely similar :-
-vm
C:\Program Files\IBM\WMBT610\jdk\jre\bin\javaw.exe
-vmargs
-Xquickstart
-Xms512m
-Xmx768m
-Xmaxf0.1
-Xminf0.05
-Xgcpolicy:gencon
-Xscmx96m
-Xshareclasses:singleJVM,keep
-Xnolinenumbers
-XX:MaxPermSize=512M
-Dsun.java2d.noddraw=true
I defrag the disks regularly.
I tried pointing to a newer version of the VM (this worked and didn't seem to suffer the problem but then other problems occurred (like plug-ins not found) so I switched back to the supllied javaws.exe, so there wasn't really enough time to see whether this actually had any permanent effect.
I have seen some suggestions about creating a new workspace, or changing the refresh rate of eClipse (not sure how to do that ?), but I was just wondering whether anyone has/is experiencing something similar and has found something which made enough difference to turn a working environment from maddening to usable ???
Thanks
Fraser. |
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| mlafleur |
| Posted: Tue Mar 17, 2009 11:16 am Post subject: |
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Acolyte
Joined: 19 Feb 2004
Posts: 73
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| I recommend increasing your memory to at least 2GB. |
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| fjb_saper |
| Posted: Tue Mar 17, 2009 6:23 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| mlafleur wrote: |
| I recommend increasing your memory to at least 2GB. |
Make sure you run with at least 2 CPU and the max memory windows will support (3.x Gig) and you will still occasionally experience slowness(switching to debug ...) Enjoy 
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MQ & Broker admin |
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| mqpaul |
| Posted: Wed Mar 18, 2009 7:50 am Post subject: I see little point in having 1.5 Gb machine and Xmx=512m |
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Acolyte
Joined: 14 Jan 2008
Posts: 66
Location: Hursley, UK
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The limiting factor for Java performance is the size of the JVM heap. -Xmx512M isn't going to be enough for a complex Eclipse environment. (That said, I run with the defaults, and don't experience your problem. But I do have 2 Gb RAM, use a stripped-down Linux environment, and have simple flows and message models.) Certainly reducing it to 512M from the default 768M is going to make things worse. I'd consider 1024M.
Of course, it might not be as simple as this. It's always important to ask what else is running on your machine. If you're also running say DB2 and a development Broker, you may have run out of memory. It's very important that the JVM does not page, but it should be big enough to avoid overfrequent garbage collection.
You can use the usual Windows Task Monitor displays, or other more exciting tools, to see if you're out of memory.
** Just noticed:
| Quote: |
| I tried pointing to a newer version of the VM (this worked and didn't seem to suffer the problem but then other problems occurred (like plug-ins not found) so I switched back to the supllied javaws.exe, so there wasn't really enough time to see whether this actually had any permanent effect. |
Changing VM should not affect finding plug-ins; it's just tha Java executable; everything else is found by Eclipse, so unless you changed classpath or working directory, it should find the same plug-ins and environment.
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Paul |
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| goffinf |
| Posted: Thu Mar 19, 2009 1:29 am Post subject: |
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Chevalier
Joined: 05 Nov 2005
Posts: 401
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Guys, thanks for your responses to-date. Of course I have seen similar advice before and tried most, but its interesting to note that we kinda accept that eClipse perfromance is going to be ... well challenging. I guess I was trying to see whether v6.1 had changed anything substantially.
Jeff mentioned running with dual CPUs and ideally 3GB RAM ... if only  . The company I work for issues 'standard' laptops (did I mention I use a laptop). The IBM T41 has a single CPU and supports a maximum of 2GB memory ... so thats what I have to work with and get the most from. Not questioning your advice Jeff but unfortunately the 'throw more tin at it' solution isn't available to me.
Paul mentioned increasing JVM heap to 1024M. I'm pretty sure I tried that and it either made things worse or no better, but I will go back and try it again and let you know.
What else is running ... well it is a complete development environment for Broker work, so MQ of course, Derby, the Broker Toolkit and a few other things of lesser note. I do watch memory utilisation very closely. For example I don't have the config mgr or broker services started by default (most of the time I don't need them and they use a whole bunch of memory). I have turned off any Windows services that I don't need (surprising how many this is). I also have projects closed in the toolkit if I'm not using them much. I don't have loads of applications running at the same time if I'm not actually using them ... yadda, yadda
Task Manger reports plenty (>500MB) of available physical memory most of the time so its hard to understand why eClipse would be paging, but the evidence is clear ... javaw.exe is CPU bound in spurts a lot of the time.
I'll keep looking. Any more tips are always welcome.
Thanks
Fraser. |
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| mqjeff |
| Posted: Thu Mar 19, 2009 4:10 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| goffinf wrote: |
| Jeff mentioned running with dual CPUs and ideally 3GB RAM ... if only |
Not me, actually...
T41? Really?
Are you really really sure that you don't have an option to get something beefier? You clearly have a well defined requirement for it - "You're paying me to do this development. It is not functional on your 'standard' laptop designed for the casual business user, which I am *not*." |
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| goffinf |
| Posted: Thu Mar 19, 2009 4:52 am Post subject: |
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Chevalier
Joined: 05 Nov 2005
Posts: 401
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Ah, sorry Jeff.
Your right of course and I am trying to make this case .. we'll see.
The Windows task manager shows huge use of Page File 1.6GB whilst at the same time showing that PHYSICAL memory is available. I guess this is the root cause. But I don't know how to reduce the PF number and force eclipse to use physical RAM ?
I'll keep digging
Fraser. |
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| gs |
| Posted: Thu Mar 19, 2009 6:23 am Post subject: |
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Master
Joined: 31 May 2007
Posts: 254
Location: Sweden
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There were problems with that particular version of the Toolkit (see APAR IZ42984).
Ifix003 was released a couple of days ago and speeded up things for me. |
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| mqpaul |
| Posted: Mon Mar 23, 2009 2:40 am Post subject: |
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Acolyte
Joined: 14 Jan 2008
Posts: 66
Location: Hursley, UK
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| goffinf wrote: |
| The Windows task manager shows huge use of Page File 1.6GB whilst at the same time showing that PHYSICAL memory is available. I guess this is the root cause. But I don't know how to reduce the PF number and force eclipse to use physical RAM ? |
I wonder if it's a Windows configuration issue. If I have to run Windows, I use a preset page file size of 2xRAM, so 4Gb on my 2Gb Thinkpad T60 laptop.
If you want to change the size, it's worth setting the size to the minimum you can, reboot, defragment the hard drive, and then reset to the size you want, and reboot again. That way you should get all the page file in one or two extents. Though I don't know how much that helps.
Also AFAIR there's a setting somewhere in the Control Panel saying something like "optimize for server use" vs "optimize for desktop". I believe the latter setting increases the priority of the desktop app when you click, which should improve Eclipse performance.
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Paul |
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