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

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.

Run Java with the command-line option -Xmx, which sets the maximum size of the heap.

See here for details.

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.

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.

If you came here to search this issue from REACT NATIVE.

Then i guess you should do this

cd android/ && ./gradlew clean && cd ..

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.

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.

Add this line to your gradle.properties file

org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

It should work. You can change MaxPermSize accordingly to fix your heap problem

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.

add the below code inside android/gradle.properties:

org.gradle.jvmargs=-Xmx4096m -XX:MaxPermSize=4096m -XX:+HeapDumpOnOutOfMemoryError
org.gradle.daemon=true
org.gradle.parallel=true
org.gradle.configureondemand=true

In my case it solved by assigning more memory to Shared build process heap size in intellij settings.

Go to intellij settings > Compiler > Shared build process heap size

Android Studio

File -> Invalidate Caches and Restart solved it for me :)

If you are using Android Studio just add these lines with gradle.properties file

org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

Java OOM Heap space issue can also arise when your DB connection pool got full.

I faced this issue because of my Hikari Connection pool (when upgraded to Spring boot 2.4.*) was full and not able to provide connections anymore (all active connections are still pending to fetch results from database).

Issue is some of our native queries in JPA Repositories contain ORDER BY ?#{#pageable} which takes a very long time to get results when upgraded.

Removed ORDER BY ?#{#pageable} from all the native queries in JPA repositories and OOM heap space issue along with connection pool issue got resolved.

If this error occurs right after execution of your junit tests, then you should execute Build -> Rebuild Project.

If this error comes up during APK generation in react-native, cd into the android folder in your project and do:

./gradlew clean

then

./gradlew assembleRelease

If error persists, then, restart your machine.

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.

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