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Increasing the JVM heap memory using Xmx doesn't work

I'm developping a javafx application which has much ui interfaces, and while opening many windows, the jvm start consumming much memory (going up tp 350mb).
When it arrives to 360mb, the programs starts lagging and end up by being crashed (nothing works, screen blocks ...) and the console show a OutOfMemoryException with Java Heap Space error
I've 6gb of memory in my computer, and tried to start the .jar file using -Xmx param, but still the operating system doesn't allow the jvm to consume more memory.
Is there anything else i should specify so that the jvm may be able to get as much memory as it needs ?

You might want to ensure that you're using:
java -Xmx1024m -jar YourApplication.jar
and not:
java -jar YourApplication.jar -Xmx1024m
Anything after the .jar is considered as argument passed to your executable Jar.

Memory overflow Java

I think that my Java Program exceeded the usage of memory allowed... this is the error that shows up in Eclipse:
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at Main.main(Main.java:228)
before than trying an implementation with better memory handling, is there any way basically to augment the memory to allocate for the program ? I would like to see the program terminating and showing the result at least.

You can allocate more memory to the process by using the -Xmx flag:
java -Xmx2G YourProgram
Will allocate 2 Gigabytes of memory to the process.
You can do this in Eclipse by going to Run Configurations, the Arguments section and adding -Xmx 2G to the VM arguments.

Increasing memory size is good, but you should also consider that probably your program has some memory leak and you really should bother about it.

You can increase heap size using the cmd-line flags
For example:
java -Xmx6g myprogram
You can get a full list (or a nearly full list, anyway) by typing java -X.

As I don't think your program is using that much memory, I suspect your program is having a memory leak somewhere.
If you could give Main.java:200 till Main.java:250 we could check for any leaks.
If you are sure your program is using that amount of memory you can either run
java -Xmx2G -jar foo.jar in the Command Prompt (Windows) or Terminal (Mac OS X or Linux)
or, if you're running your program in Eclipse under Linux, do the following:
1) Make sure Eclipse is closed
2) Open your favorite text editor at your eclipse.ini file (Default location: /usr/lib/eclipse/eclipse.ini)
3) Search for --Xmx512M and increase this number (i.e. --Xmx2G)
4) Save the file and restart Eclipse
For any explaination about --Xmx and --Xms I refer to Eclipse memory settings when getting "Java Heap Space" and "Out of Memory"
Happy coding :) -Charlie

Memory issue when trying to start a minecraft server via a python script

Okay iv been working on a hand full of tool to help maintain a large number a of game servers hosted on a single computer. What i'm am doing is lunching a .bat file from a python script. That bat file sets the servers prams like max memory and things of that nature. I open and run the .bat file with the following function.
def StartServer(path,file):
if file not in MK.keys():
l = Popen(file, cwd=path)
MK[file]=l
stdout, stderr = l.communicate()
else:
MK[file].terminate()
this function is called in one of two ways the
1st way is to start the program.
thread.start_new_thread( StartServer, (path,File, ) )
2nd the close the program
StartServer(path,File)
StartServer see the reentry and terminates the specified program...
and this works great for programs that need very little ram, like a bat file such as
#echo Hello world.
#pause
however when trying to allocate more ram for a java program such as,
#ECHO OFF
SET BINDIR=%~dp0
CD /D "%BINDIR%"
"%ProgramFiles%\Java\jre7\bin\java.exe" -Xmx4096M -Xms4096M -jar Minecraft_RKit.jar user:password
PAUSE
I receive a memory error from the BAT file as follows. this is from the bat file not from the python side
Invalid mat heap size: -Xmx4096M
The specified size exceeds the maximum representable size.
Error: Could not create java virtual machine.
Error: A fatal exception has occurred. Program will exit.
Press any key to continue . . .
Note: I prefer to use both python and the bat file thank you in advance!

You are attempting to start a 32-bit JVM, giving it a heap size that is too large for a 32-bit architecture. The maximum heap size is something less than 3Gb for a 32-bit JVM. The actual limit depends on the OS (which determines how much of the address space is made available to applications) and on how much non-heap memory is used by the JVM.
Either reduce the max heap size, or switch to a 64-bit JVM (and a 64-bit OS).

Eclipse Memory Analyser,but always shows An internal error occurred?

java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid2584.hprof ...
Heap dump file created [106948719 bytes in 4.213 secs]
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2760)
at java.util.Arrays.copyOf(Arrays.java:2734)
at java.util.ArrayList.ensureCapacity(ArrayList.java:167)
at java.util.ArrayList.add(ArrayList.java:351)
at Main.main(Main.java:15)
But when i open head dump java_pid2584.hprof via Eclipse Memory Analyser,but there is always message:
An internal error occurred during:
"Parsing heap dump from **\java_pid6564.hprof'".Java heap space

The problem is that Eclipse Memory Analyser does not have enough heap space to open the Heap dump file.
You can solve the problem as follows:
open the MemoryAnalyzer.ini file
change the default -Xmx1024m to a larger size

Note that on OS X, to increase the memory allocated to MAT, you need to right-click mat.app and show the package contents. The MemoryAnalyzer.ini file is under /Contents/Eclipse.

Solution for same issue for Memory Analyzer plugin in Eclipse in MAC OS X El Capitan.
I was facing the same issue but with the eclipse plugin and I did not have any Memory Analyzer App in Applications Folder. The solution which worked for me was:
Right Click on Eclipse icon and select Show Package Content.
Go to Contents>Eclipse
Open Eclipse.ini
Change value -Xmx1024m to -Xmx2048m
Restart Eclipse

On OS X 11.5 (El Cap) modifying MemoryAnalyzer.app/Contents/MacOS/MemoryAnalyzer.ini does not work! This is because it's looking for the MemoryAnalyzer.ini in a different place.
On my computer, it was looking for:
MemoryAnalyzer.app/Contents/Eclipse/MemoryAnalyzer.ini but the real .ini file was:
MemoryAnalyzer.app/Contents/MacOS/MemoryAnalyzer.ini.
In order for your changes to take effect, copy the existing .ini file into the new location.
To find where MemoryAnalyzer is looking for the ini file, you can run:
sudo su
cd ...MemoryAnalyzer.app/Contents/MacOS/
dtruss ./MemoryAnalyzer 2>&1 | grep ini

If Memory Analyser is used from Eclipse, then edit your eclipse.ini file to increase the vm argument to -Xmx1024m or higher. This worked for me.
http://wiki.eclipse.org/index.php/MemoryAnalyzer/FAQ#Out_of_Memory_Error_while_Running_the_Memory_Analyzer

As suggested by others, its two step simple process:-
open the MemoryAnalyzer.ini file from your MAT installation directory.
change the default -Xmx1024m to a larger size for e.g. if you have to analyze a 4GB heap dump then you can replace -Xmx1024m with -Xmx5g or -Xmx6g
For more details refer:-
https://better-coding.com/solved-eclipse-mat-java-heap-space-error/

For my experience add in MemoryAnalyzer.ini, Xms and Xmx to the max as your materiel possibilities. G1GC is faster and -XX:-UseGCOverheadLimit is need because gc usage can be high and time consuming, and maybe -XX:+UseStringDeduplication is the key to consume less memory
-vmargs
-Xms8g
-Xmx8g
-XX:-UseGCOverheadLimit
-XX:+UseG1GC
-XX:+UseStringDeduplication

If you are using Mac, try running the executable inside the mat.app 'folder' with -data option, by which you can specify a writable path:
cd mat.app/Contents/MacOS
./MemoryAnalyzer -data <writable_path>

I tried all the solutions here as well, while still getting the same error and the reason eclipse was trying to open the .hprof file as a text file due to wrong or unknown file type / editor association.
Solution: Right click on the file, select open with, then select Others, and select Eclipse Memory Analyzer.
Worked with 700MB dump, and worked with 2G dump on an eclipse heap of about 600M.

An internal error has occurred. Java heap space
Ans: GO to Your Project Work space
open .setting folder
Delete all file of .setting folder.
after you can compile
now there is no error Like Heap space
Enjoy :)

You may reduce your application memory limit, and then again take a dump. Eclipse Memory Analyser puts dump file to memory - I suspect that your Eclipse has less memory than the limit of application.
You can also do the opposite and increase the memory limit for Eclipse, but if your application works on a server, it will be hard to match in size of memory.

Hibernate - OutOfMemoryError - java heap size

I'm currently having this problem where I am executing a query that will load large of records. At first execution, it is successful, but when I
execute again, I am having java heap size out of memory.
I Know I can increase java heap size using command line, but that requires a compiled jar file.
But I am currently on the development process, so how can I increase java heap size in that case?
Im using Elipse as my IDE.
Thanks for any response.

It doesn't require a compiled jar file. Choose Run - Run configurations... - Select your run configuration - Arguments tab. Then enter the appropriate command line argument in the VM arguments text box: -Xmx1024m for example.

You can modify the eclipse.ini file located inside of our eclipse directory .There you will find Xms40m Xmx256m parameter with some value , you can increase it to Xms256m Xmx1024m . Then check whether outofmemory error is still there . If its there then try tuning these parameter slightly increasing and check.

Apperently that was not enough for an answer... well, let me just copy the text from those answers instead :S
You can use the environment variable _JAVA_OPTIONS to set the default heap size. This will change the heap size for all Java programs. Like this:
export _JAVA_OPTIONS="-Xmx1g"