How to detect "almost out of memory" in JRockit?

I would appreciate any advice on how to build an "almost out of memory" detector to ensure the JVM does not crash when the user mis-configures our application.
So far I have encountered these problems with JRockit 27.3 (JDK 5.0) in limited testing on windows. This test is just one part of the app, using only 50mb. I've tried 27.4 and it appears to have the same issues.
1) Runtime.freeMemory returns 0 often, even when lots of memory is still available (28% was returned in the previous call!). If the thread sleeps for 30 millisec a resonable value might be returned. (but still gets 0 fairly often).
2) There is huge oscillation in the free memory reported even when there is > 15% memory left. The test program allocates some intermediate data (10kb or so), then the more permanent data (500 bytes or so). Successive calls to free memory in the loop can oscillate from 8% left to 17% left.
3) As memory gets more than 50% used, the GC algorithm switches around several times. I was using -Xgcprio:pausetime with pause time of 600ms. The observation was the GC algorithm switches and some full GC's would take as much as 8 seconds (this test using 100mb of memory) and during this time my polling thread (250ms) does not run. This is a problem since there are a couple of polling threads that expect to run at least once per second.
4) It appears the basic Java heap usage is quite different with JRockit. The test code can allocate 50k result objects (about 500 bytes each) when run in Sun JVM, but only 33k objects in JRockit. (-Xmx is set to 50M for these tests, the real app runs with 3 to 12GB based on customer hardware)

Can you post your test code here?
Thanks,
/Staffan

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Almost out of memory

hello I enclose a screenshot of my memory
I am almost out of memory but I have no idea what takes so much space?
Ofcourse I am talking about the 320 GB SATA disk, the other are allright
you can see it is called other, how can I find out what it is?
I first thought it was dropbox,as I downloaded a lot of files to dropbox, but I have desynced all my folders and I still get the same amount of space.
The helpdesk of dropbox tells me that my mac cannot contain contents anymore if I have desynced the folders...
I want to free my mac from this yellow stuff from which I do not know what it is. Has anybody an idea how I can figure this out?
Txs,
Marcel Steinbach

For information about the Other category in the Storage display, see this support article.
Empty the Trash if you haven't already done so. If you use iPhoto, empty its internal Trash first:
iPhoto ▹ Empty Trash
Do the same in other applications, such as Aperture, that have an internal Trash feature. Then reboot. That will temporarily free up some space.
According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation. You also need enough space left over to allow for growth of the data. There is little or no performance advantage to having more available space than the minimum Apple recommends. Available storage space that you'll never use is wasted space.
When Time Machine backs up a portable Mac, some of the free space will be used to make local snapshots, which are backup copies of recently deleted files. The space occupied by local snapshots is reported as available by the Finder, and should be considered as such. In the Storage display of System Information, local snapshots are shown asBackups. The snapshots are automatically deleted when they expire or when free space falls below a certain level. You ordinarily don't need to, and should not, delete local snapshots yourself. If you followed bad advice to disable local snapshots by running a shell command, you may have ended up with a lot of data in the Other category. Reboot and it should go away.
See this support article for some simple ways to free up storage space.
You can more effectively use a tool such as OmniDiskSweeper (ODS) to explore the volume and find out what's taking up the space. You can also delete files with it, but don't do that unless you're sure that you know what you're deleting and that all data is safely backed up. That means you have multiple backups, not just one.
Deleting files inside an iPhoto or Aperture library will corrupt the library. Any changes to a photo library must be made from within the application that created it. The same goes for Mail files.
Proceed further only if the problem isn't solved by the above steps.
ODS can't see the whole filesystem when you run it just by double-clicking; it only sees files that you have permission to read. To see everything, you have to run it as root.
Back up all data now.
If you have more than one user account, make sure you're logged in as an administrator. The administrator account is the one that was created automatically when you first set up the computer.
Install ODS in the Applications folder as usual. Quit it if it's running.
Triple-click anywhere in the line of text below on this page to select it, then copy the selected text to the Clipboard by pressing the key combination command-C:
sudo /Applications/OmniDiskSweeper.app/Contents/MacOS/OmniDiskSweeper
Launch the built-in Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste into the Terminal window (command-V). You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning to be careful. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator.
The application window will open, eventually showing all files in all folders, sorted by size with the largest at the top. It may take a few minutes for ODS to finish scanning.
I don't recommend that you make a habit of doing this. Don't delete anything while running ODS as root. If something needs to be deleted, make sure you know what it is and how it got there, and then delete it by other, safer, means. When in doubt, leave it alone or ask for guidance.
When you're done with ODS, quit it and also quit Terminal.

My MBA won't empty the trash and I'm almost out of memory. It's not a year old yet.

My MBA won't empty the trash and I'm almost out of memory. It can't upgrade too! I just got it last august 2013.

Mac troubleshooting: What to do when the Trash won’t empty | Macworld

How to cope with Out of Memory Errors

Hi, I am distributing a desktop application to the general public written in Java 1.4.2. How much memory is required is approximately propertional to how many files they load so Ive tried to pre-emtp OutOfMemoryErrors by checking when memory usage is 95% and preventing the loading of additional files above this level with the following code:
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I tried removing this code, but then user can get an OutOfMemory error whcih can cause problems with whatever code was running at the time and leave the application in an inconsistent state, if I just exit the application immediately it would be very annoying for users that are int he middle of something.
I also have adjusted the -Xms and -Xmx settings but cannot decide on a suitable default.
What I would ideally like the application to do is to extend its heap space as required upto the limits of the users machine, and if it reaches memory limits handle the lack of memory in a releiable manner allowing the user to continue using the application in a safe way

Unfortunately the metadata is stored displayed within a JTable, so even if If I had in in a Database I think it would all have to be loaded into memory for display within the JTbale in a timely fashion.
Anyway I think Ive found the problem with the original code, it was reporting memory low when almost all the allocated memory was being used but had'nt accounted for the fact that maxMemory limit had not been reached so more memory could be allocated.
I think the correct code is:
protected static void checkMemory()
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            Runtime.getRuntime().gc();
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The Photoshop 6 beta program froze while using the crop tool on an image size of 8052x5368. I tried to save a file in another program while waiting for the crop to finish (usually about 1 second) and got an out-of-memory error. I checked the D: driv where the file in the other program was saved. I have a flash C: drive and is not selected in the scratch disk preference. Two scratch disks, E: and G:, are selected with a total of about 800GB free space. After closing PS6Beta, the D: drive recovered about 164GB. The D: drive is not selected in the Scratch Disk list. I work with larger files and anticipate this problem again.How can I trap information for Adobe next time?
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Logical processor count: 8
Processor speed: 2664 MHz
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Memory available to Photoshop: 3255 MB
Memory used by Photoshop: 60 %
Image tile size: 128K

The problem remains for how the c: and d: drives were not selected in the scratch disk list. I tried again with only E: and G: drives and the file completed after 20 minutes with a 27.7G file. It would have been an ovious problem if the "info" diaglog box included the projected file size and/or dimensional units (px or in) because I use the dialog for verifying the size of the image. I wanted to make a 300 x400px image rather than a 300x400inch image( 90000x120000px).
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Hi,
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message(ORA_JAVA.LAST_ERROR);
--Clean up
ORA_JAVA.CLEAR_ERROR;

No need to double-post... most questions are answered pretty quickly...

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Hello,i did a web application (asp.net/c#/crystal reports),i used more than 35 tableAdapter and when i'm trying report after some time i remark the memory increase more and more until i get Out Put memory Exception. how can i fix this problem ?
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Hi ghilasdz,
Thank you for posting in MSDN forum.
Since this forum is to discuss: Visual Studio WPF/SL Designer, Visual Studio Guidance Automation Toolkit, Developer Documentation and Help System, and Visual Studio Editor.
So I’m afraid that it is not the correct forum for this issue.
As you said that the exception out of memory for the crystal reports, I suggest you can post this issue directly to the
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SAP Crystal Reports, maybe you will get some useful message.
http://scn.sap.com/thread/1888746
Thanks for your understanding.
Best Regards,
We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
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Hi,
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BH
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How to detect "almost out of memory" in JRockit?

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