Sorry for asking the question, should have searched a bit more.
Im running weka with a rather large dataset and a memory intesive algoithm. I need all the heap space I cant get!
This works:
java -jar -Xmx2048m weka.jar &
But this does not
java -jar -Xmx4096m weka.jar &
I get:
Error occurred during initialization of VM Could not reserve enough
space for object heap Could not create the Java virtual machine.
By some quick searching I found that this is the upper limit
java -jar -Xmx2594m weka.jar &
I have 4GB ram but a 32 bit machine. Why can't I use 2^32 bytes = 4096MB of memory?
For the future I am wondering if I can run java with e.g. hundreds of GB of heap space if I have the correct hardware and OS?
I have both 1.6 and 1.7 JVM installed:
$java -showversion
java version "1.6.0_24"
OpenJDK Runtime Environment (IcedTea6 1.11.4) (6b24-1.11.4-1ubuntu0.12.04.1)
OpenJDK Server VM (build 20.0-b12, mixed mode)
I have 4GB ram but a 32 bit machine. Why can't I use 2^32 bytes = 4096MB of memory?
For the future I am wondering if I can run java with e.g. hundreds of GB of heap space if I have the correct hardware and OS?
For 4 GB I suggest you use a 64-bit OS and possibly a 64-bit JVM as the limit for the heap size can be as small as 1.2 GB (on Windows XP)
If you want larger JVMs I suggest making sure you have 64-bit OS and JVM and you have more memory than the size of the JVM. e.g. if you want a 40 GB heap you need something like 48 GB or 64 GB of memory.
Use the 64-bit version of Java which allows you to use more memory. This is the limit of the 32-bit Java virtual machine.
If you have 4GB of RAM how can you expect that all will be available to your JVM? What about the OS the JVM is running in, this will also require memory. The way it works is that even though you can address all 4GB generally an OS will limit the amount available per process.
You are not able to have an allocation of 4096m because. It tries to get a single block of 4096m. Which is not possible at any given point of time. So you can use some smaller values between
3000-4000. or make sure your RAM is not used by any of the processes
Related
I am trying to run a Java tool in Linux Ubuntu system and I keep getting the following error after the program imports 12% of the data:
Fata Error:
Exception in thread 'Thread-l" java.lang.OutOfMemoryError: java heap space
I tried to set the heap size using
java -Xms8G -Xmx16G -jar Haploview.jar
but the error appears again exactly at same point after just using less than 500M Of the allocated Ram.
Using the command 'free -m' I can see that there are lots of free RAM memory left but I don't know why Java do not use it
According to the specification Haploview allocates 512 MB of memory by default. You can increase the memory up to 2000 MB via java -jar Haploview.jar -memory 2000.
For details see https://www.broadinstitute.org/haploview/frequent-questions
But a memory larger than 2 GB is most likely not possible because Haploview seems to be a 32-bit application which is limited to a memory
of 2 GB independent of the underlying OS (32 Bit or 64 Bit).
See https://haploview.software.informer.com/download/
and Memory limit to a 32-bit process running on a 64-bit Linux OS
The eclipse on my work computer was working with VM argument -Xms40m and -Xmx512m and it is really slow and freezes a lot, I wanted to increase it to -Xmx1024m, but every time I did so I got the error "Could not create the Java Virtual Machine".
The computer has 3.5GB RAM, WIN XP (32-bit), Java 1.6_18
What could be the reason? Is it related to other arguments?
UPDATE:
I changed the -vm argument so it will use the jvm.dll that comes with the jrockit JDK and I was able to increase the max heap size to 1024m.
Also, on my home computer (WIN 7, 32-bit, 2GB RAM, java 1.7.0_21-b11), I was able to increase it 1024m as well.
The maximum amount of memory available on Windows 32-bit processes is (generally speaking) 2GB. That includes everything for your JVM, not only the application heap. People report various numbers for the maximum heap that can use for a 32-bit JVM, but 1200m is a common figure. It seems to be lower for you. Best would be to switch to the 64-bit JVM, if you can.
Other questions:
How much memory can a 32 bit process access on a 64 bit operating system?
Java maximum memory on Windows XP
I am running at the same computer a java game-server and a game-client
the game-client with
java -Xms512m -Xmx1024m -cp etc etc
and the game-server
java -Xmx1024M -Xms1024M -jar etc etc
Computer Properties:
Windows 7 64 bit
8GB RAM
CPU i5-2500 # 3.3GHz
Intel HD Graphics
Problem: The game-client experience serious lags. At the game-server is also connected via LAN another player with no lag issues!
Has the problem of the lag to do anything with java virtual machine? Am I using one instance of machine or two?
Can I setup something different in order to optimize the performance?
I am thinking that the problem has to do with the fact that one machine is running and its max memory is not enough for both instances, but I do not really know how to solve that.
Edit: No app run out of memory.
Solution:
1:
Updated Java version from:
java version "1.6.0_31"
Java(TM) SE Runtime Environment (build 1.6.0_31-b05)
Java HotSpot(TM) 64-Bit Server VM (build 20.6-b01, mixed mode)
to
java version "1.7.0_15"
Java(TM) SE Runtime Environment (build 1.7.0_15-b03)
Java HotSpot(TM) 64-Bit Server VM (build 23.7-b01, mixed mode)
2:
Changed the server properties in order to minimize requirements, this seems to be the main reason.
3:
Increased memory:
game-client with java -Xms1024m -Xmx1024m -cp etc etc
and the game-server java -Xmx2048M -Xms2048M -jar etc etc
Server runs at about 700MB now.
Has the problem of the lag to do anything with java virtual machine?
Possibly. You haven't presented enough evidence to be sure one way or the other.
The puzzling thing is that the your client running on a different machine is not laggy.
Am I using one instance of machine or two?
You are running two copies of java then you will have two JVMs.
Can I setup something different in order to optimize the performance?
The answer is probably yes. But you haven't provided enough information to allow us to make solid suggestions.
Lagginess can be caused by a number of things, including:
A network with high latency.
A JVM that has a heap that is too small.
An application that is generating lots of garbage and triggering an excessive number of garbage collection.
A mix of applications that is competing for resources; e.g. physical memory, CPU time or disc or network I/O time.
If you are going to get to the root cause of your problem, you will need to do some monitoring to figure out which of the above is the likely problem. Use the task manager or whatever to check whether the system is CPU bound, short of memory, doing lots of disk or network stuff, etc. Use VisualVM to see what is going on inside the JVMs.
Alternatively, you could try to fix with some totally unscientific "knob twiddling":
try making the -Xms and -Xmx parameters the same (that may reduce lagginess at the start ...)
try increasing the sizes of the JVMs' heaps; e.g. make them 2gb instead of 1gb
try using a more recent version of Java
try using a 64 bit JVM so that you can increase the heap size further
try enabling the CMS or G1 collectors (depending on what version of JVM you are using).
If I knew more about what you were currently using, I could possibly give more concrete suggestions ...
You are using two java apps in same computer, resulting in 2 JVMs running.
For a 64 bit system with 8GB RAM, its recommended to use max 2GB(25% of Physical memory OR 75% of free physical memory up to 2 GB) for JVM for better performance.
You may have to look on JVM size adjustment. For better performance, Xms and Xmx size can be kept same with a max size bracket.
Assigning memory size to Heap is not the only area to think of. JVM uses more memory than just Heap. Others memory areas like Thread Stack, Method areas, Class Loader Subsystem, Native Method Stack etc.
While both of the apps(game-server, game-client) are running, there is a chance of issue in memory management by OS between both apps, resulting in slowness.
In that case, client app can be deployed in another core, if available.
I use ubuntu 10.04 LTS 64bit and my system has 4 GB RAM.
I run a java program that need more than 1.1GB memory but the operating system does not allow my program to get more than 1.1GB while only 2.1GB of RAM is used and 1.9GB are free, what is the problem? (This problem is not just for this program, I run another program and has same problem.)
what should I do?
Looks like you are running a java application. Make sure to
Run a 64 bit JVM, if you need more than about 4GB memory. For this to work, you shold have a 64 bit OS
Increase the max heap size by the JVM switch
-Xms <initial size> -Xmx <max size>
Sounds like you programs are compiled as 32bit programs despite that you are running on a 64bit configuration.
I'd like to run a very simple bot written in java on my VPS.
I want to limit jvm memory to let's say 10MB (I doubt it would need any more).
I'm running the bot with the following command:
java -Xms5M -Xmx10M -server -jar
IrcBot.jar "/home/jbot"
But top shows that actual memory reserved for java is 144m (or am I interpreting things wrong here?).
13614 jbot 17 0 144m 16m 6740
S 0.0 3.2 0:00.20 java
Any ideas what can be wrong here?
Java version "1.6.0_20" Java(TM) SE Runtime Environment (build 1.6.0_20-b02) Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode)
BTW. I'm running CentOS - if it matters.
EDIT:
Thank you for your answers.
I can't really accept any of them, since it turns out the problem lies within the language i choose to write the program, not the JVM itself.
-Xmx specifies the max Java heap allocation (-Xms specifies the min heap allocation). The Java process has its own overhead (the actual JVM etc), plus the loaded classes and the perm gen space (set via -XX:MaxPermSize=128m) sits outside of that value too.
Think of your heap allocation as simply Java's "internal working space", not the process as a whole.
Try experimenting and you'll see what I mean:
java -Xms512m -Xmx1024m ...
Also, try using a tool such as JConsole or JVisualVM (both are shipped with the Sun / Oracle JDK) and you'll be able to see graphical representations of the actual heap usage (and the settings you used to constrain the size).
Finally, as #Peter Lawrey very rightly states, the resident memory is the crucial figure here - in your case the JVM is only using 16 MiB RSS (according to 'top'). The shared / virtual allocation won't cause any issues as long as the JVM's heap isn't pushed into swap (non-RAM). Again, as I've stated in some of the comments, there are other JVM's available - "Java" is quite capable of running on low resource or embedded platforms.
Xmx is the max heap size, but besides that there's a few other things that the JVM needs to keep in memory: the stack, the classes, etc. For a brief introduction see this post about the JVM memory structure.
The JVM maps in shared libraries which are about 150m. The amount of virtual memory used is unlikely to be important to use if you are trying to minimise physical main memory.
The number you want to look at is the resident memory which is amount of physical main memory actually used (which is 16 MB)