How to deal with java lang OutOfMemoryError Java heap space error

Question

I am writing a client-side Swing application  graphical font designer  on Java 5  Recently  I am running into java lang OutOfMemoryError  Java heap space error because I am not being conservative on memory usage  The user can open unlimited number of files  and the program keeps the opened objects in the memory  After a quick research I found Ergonomics in the 5 0 Java Virtual Machine and others saying on Windows machine the JVM defaults max heap size as 64MB   Given this situation  how should I deal with this constraint   I could increase the max heap size using command line option to java  but that would require figuring out available RAM and writing some launching program or script  Besides  increasing to some finite max does not ultimately get rid of the issue   I could rewrite some of my code to persist objects to file system frequently  using database is the same thing  to free up the memory  It could work  but it s probably a lot work too   If you could point me to details of above ideas or some alternatives like automatic virtual memory  extending heap size dynamically  that will be great

User · Answer

By default for development JVM uses small size and small config for other performance related features. But for production you can tune e.g. (In addition it Application Server specific config can exist) -> (If there still isn't enough memory to satisfy the request and the heap has already reached the maximum size, an OutOfMemoryError will occur)

-Xms<size>        set initial Java heap size
-Xmx<size>        set maximum Java heap size
-Xss<size>        set java thread stack size

-XX:ParallelGCThreads=8
-XX:+CMSClassUnloadingEnabled
-XX:InitiatingHeapOccupancyPercent=70
-XX:+UnlockDiagnosticVMOptions
-XX:+UseConcMarkSweepGC
-Xms512m
-Xmx8192m
-XX:MaxPermSize=256m (in java 8 optional)

For example: On linux Platform for production mode preferable settings.

After downloading and configuring server with this way http://www.ehowstuff.com/how-to-install-and-setup-apache-tomcat-8-on-centos-7-1-rhel-7/

1.create setenv.sh file on folder /opt/tomcat/bin/

   touch /opt/tomcat/bin/setenv.sh

2.Open and write this params for setting preferable mode.

nano  /opt/tomcat/bin/setenv.sh 

export CATALINA_OPTS="$CATALINA_OPTS -XX:ParallelGCThreads=8"
export CATALINA_OPTS="$CATALINA_OPTS -XX:+CMSClassUnloadingEnabled"
export CATALINA_OPTS="$CATALINA_OPTS -XX:InitiatingHeapOccupancyPercent=70"
export CATALINA_OPTS="$CATALINA_OPTS -XX:+UnlockDiagnosticVMOptions"
export CATALINA_OPTS="$CATALINA_OPTS -XX:+UseConcMarkSweepGC"
export CATALINA_OPTS="$CATALINA_OPTS -Xms512m"
export CATALINA_OPTS="$CATALINA_OPTS -Xmx8192m"
export CATALINA_OPTS="$CATALINA_OPTS -XX:MaxMetaspaceSize=256M"

3.service tomcat restart

Note that the JVM uses more memory than just the heap. For example Java methods, thread stacks and native handles are allocated in memory separate from the heap, as well as JVM internal data structures.

User · Answer

Big caveat ---- at my office  we were finding that  on some windows machines  we could not allocate more than 512m for Java heap  This turned out to be due to the Kaspersky anti-virus product installed on some of those machines  After uninstalling that AV product  we found we could allocate at least 1 6gb    i e    -Xmx1600m  m is mandatory other wise it will lead to another error  Too small initial heap   works   No idea if this happens with other AV products but presumably this is happening because the AV program is reserving a small block of memory in every address space  thereby preventing a single really large allocation

User · Answer

You could specify per project how much heap space your project wants  Following is for Eclipse Helios Juno Kepler   Right mouse click on   Run As - Run Configuration - Arguments - Vm Arguments     then add this  -Xmx2048m

User · Answer

Note that if you need this in a deployment situation  consider using Java WebStart  with an  ondisk  version  not the network one - possible in Java 6u10 and later  as it allows you to specify the various arguments to the JVM in a cross platform way   Otherwise you will need an operating system specific launcher which sets the arguments you need

User · Answer

I have faced same problem from java heap size   I have two solutions if you are using java 5 1 5     just install jdk1 6 and go to the preferences of eclipse and set the jre path of jav1 1 6 as you have installed  Check your VM argument and let it be whatever it is  just add one line below of all the arguments present in VM arguments as  -Xms512m  -Xmx512m -XX MaxPermSize    m 192m     I think it will work

User · Answer

Run Java with the command-line option -Xmx  which sets the maximum size of the heap   See here for details

User · Answer

I would like to add recommendations from oracle trouble shooting article   Exception in thread thread name  java lang OutOfMemoryError  Java heap space     The detail message Java heap space indicates object could not be allocated in the Java heap  This error does not necessarily imply a memory leak   Possible causes    Simple configuration issue  where the specified heap size is insufficient for the application  Application is unintentionally holding references to objects  and this prevents the objects from being garbage collected  Excessive use of finalizers        One other potential source of this error arises with applications that make excessive use of finalizers  If a class has a finalize method  then objects of that type do not have their space reclaimed at garbage collection time   After garbage collection  the objects are queued for finalization  which occurs at a later time   finalizers are executed by a daemon thread that services the finalization queue  If the finalizer thread cannot keep up with the finalization queue  then the Java heap could fill up and this type of OutOfMemoryError exception would be thrown    One scenario that can cause this situation is when an application creates high-priority threads that cause the finalization queue to increase at a rate that is faster than the rate at which the finalizer thread is servicing that queue

User · Answer

Easy way to solve OutOfMemoryError in java is to increase the maximum heap size by using JVM options -Xmx512M  this will immediately solve your OutOfMemoryError  This is my preferred solution when I get OutOfMemoryError in Eclipse  Maven or ANT while building project because based upon size of project you can easily ran out of Memory   Here is an example of increasing maximum heap size of JVM  Also its better to keep -Xmx to -Xms ration either 1 1 or 1 1 5 if you are setting heap size in your java application   export JVM ARGS  -Xms1024m -Xmx1024m   Reference Link

User · Answer

I read somewhere else that you can try - catch java lang OutOfMemoryError and on the catch block  you can free all resources that you know might use a lot of memory  close connections and so forth  then do a System gc   then re-try whatever you were going to do   Another way is this although  i don t know whether this would work  but I am currently testing whether it will work on my application   The Idea is to do Garbage collection by calling System gc   which is known to increase free memory  You can keep checking this after a memory gobbling code executes     Mimimum acceptable free memory you think your app needs long minRunningMemory    1024 1024    Runtime runtime   Runtime getRuntime     if runtime freeMemory   lt minRunningMemory   System gc

User · Answer

If you keep on allocating  amp  keeping references to object  you will fill up any amount of memory you have   One option is to do a transparent file close  amp  open when they switch tabs  you only keep a pointer to the file  and when the user switches tab  you close  amp  clean all the objects    it ll make the file change slower    but      and maybe keep only 3 or 4 files on memory   Other thing you should do is  when the user opens a file  load it  and intercept any OutOfMemoryError  then  as it is not possible to open the file  close that file  clean its objects and warn the user that he should close unused files   Your idea of dynamically extending virtual memory doesn t solve the issue  for the machine is limited on resources  so you should be carefull  amp  handle memory issues  or at least  be carefull with them    A couple of hints i ve seen with memory leaks is   --  Keep on mind that if you put something into a collection and afterwards forget about it  you still have a strong reference to it  so nullify the collection  clean it or do something with it    if not you will find a memory leak difficult to find   --  Maybe  using collections with weak references  weakhashmap     can help with memory issues  but you must be carefull with it  for you might find that the object you look for has been collected   --  Another idea i ve found is to develope a persistent collection that stored on database objects least used and transparently loaded  This would probably be the best approach

User · Answer

In android studio add change this line at the end of gradle properties  Global Properties       org gradle jvmargs -XX  MaxHeapSize  1024m -Xmx1024m   if it doesn t work you can retry with bigger than 1024 heap size

User · Answer

VM arguments worked for me in eclipse  If you are using eclipse version 3 4  do the following  go to Run -- gt  Run Configurations -- gt  then select the project under maven build --  then select the tab  JRE  --  then enter -Xmx1024m   Alternatively you could do Run -- gt  Run Configurations -- gt  select the  JRE  tab -- gt  then enter -Xmx1024m  This should increase the memory heap for all the builds projects  The above memory size is 1 GB  You can optimize the way you want

User · Answer

Increasing the heap size is not a  fix  it is a  plaster   100  temporary  It will crash again in somewhere else  To avoid these issues  write high performance code    Use local variables wherever possible  Make sure you select the correct object  EX  Selection between String  StringBuffer and StringBuilder  Use a good code system for your program EX  Using static variables VS non static variables  Other stuff which could work on your code  Try to move with multy THREADING

User · Answer

If everything else fails  in addition to increasing the max heap size try also increasing the swap size  For Linux  as of now  relevant instructions can be found in https   linuxize com post create-a-linux-swap-file    This can help if you re e g  compiling something big in an embedded platform

User · Answer

Follow below steps    Open catalina sh from tomcat bin  Change JAVA OPTS to   JAVA OPTS  -Djava awt headless true -Dfile encoding UTF-8 -server -Xms1536m  -Xmx1536m -XX NewSize 256m -XX MaxNewSize 256m -XX PermSize 256m  -XX MaxPermSize 256m -XX  DisableExplicitGC   Restart your tomcat

User · Answer

if you got this error when you launch eclipse birt 1- you will go in the file of the eclipse configuration 2- you must open eclipse init 3- modified the RAM memory  you can increase this  i give an example  my old information was   -Xmx128m -XX MaxPermSize 128m the new modification that i opered   -Xmx512m -XX MaxPermSize 512m this modification will permit me to resolve java heap space when i launch my report in my browser  Thanks

User · Answer

Regarding to netbeans  you could set max heap size to solve the problem    Go to  Run   then --   Set Project Configuration  --   Customise  --   run  of its popped up window --   VM Option  --  fill in  -Xms2048m -Xmx2048m

User · Answer

Yes  with -Xmx you can configure more memory for your JVM   To be sure that you don t leak or waste memory  Take a heap dump and use the Eclipse Memory Analyzer to analyze your memory consumption

User · Answer

Ultimately you always have a finite max of heap to use no matter what platform you are running on  In Windows 32 bit this is around 2GB  not specifically heap but total amount of memory per process   It just happens that Java chooses to make the default smaller  presumably so that the programmer can t create programs that have runaway memory allocation without running into this problem and having to examine exactly what they are doing    So this given there are several approaches you could take to either determine what amount of memory you need or to reduce the amount of memory you are using  One common mistake with garbage collected languages such as Java or C  is to keep around references to objects that you no longer are using  or allocating many objects when you could reuse them instead  As long as objects have a reference to them they will continue to use heap space as the garbage collector will not delete them   In this case you can use a Java memory profiler to determine what methods in your program are allocating large number of objects and then determine if there is a way to make sure they are no longer referenced  or to not allocate them in the first place  One option which I have used in the past is  JMP  http   www khelekore org jmp    If you determine that you are allocating these objects for a reason and you need to keep around references  depending on what you are doing this might be the case   you will just need to increase the max heap size when you start the program  However  once you do the memory profiling and understand how your objects are getting allocated you should have a better idea about how much memory you need    In general if you can t guarantee that your program will run in some finite amount of memory  perhaps depending on input size  you will always run into this problem  Only after exhausting all of this will you need to look into caching objects out to disk etc  At this point you should have a very good reason to say  I need Xgb of memory  for something and you can t work around it by improving your algorithms or memory allocation patterns  Generally this will only usually be the case for algorithms operating on large datasets  like a database or some scientific analysis program  and then techniques like caching and memory mapped IO become useful

User · Answer

If this issue is happening in Wildfly 8 and JDK1 8 then we need to specify MaxMetaSpace settings instead of PermGen settings   For example we need to add below configuration in setenv sh file of wildfly  JAVA OPTS   JAVA OPTS -XX MaxMetaspaceSize 256M   For more information  please check Wildfly Heap Issue

User · Answer

If you need to monitor your memory usage at runtime  the java lang management package offers MBeans that can be used to monitor the memory pools in your VM  eg  eden space  tenured generation etc   and also garbage collection behaviour   The free heap space reported by these MBeans will vary greatly depending on GC behaviour  particularly if your application generates a lot of objects which are later GC-ed  One possible approach is to monitor the free heap space after each full-GC  which you may be able to use to make a decision on freeing up memory by persisting objects   Ultimately  your best bet is to limit your memory retention as far as possible whilst performance remains acceptable  As a previous comment noted  memory is always limited  but your app should have a strategy for dealing with memory exhaustion

[java] How to deal with "java.lang.OutOfMemoryError: Java heap space" error?

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