OutOfMemoryError Java heap space Kryonet

[Lukas S]

Hey :)

Got following error:

Exception in thread "Client" Exception in thread "Client" 25:12 INFO: [kryonet] Connection 32 disconnected.Exception in thread "Client" Exception in thread "Client" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Client" java.lang.OutOfMemoryError: Java heap space
Exception in thread "Client" Exception in thread "Client" java.lang.OutOfMemoryError: Java heap space
    at java.util.ArrayList.iterator(Unknown Source)
    at sun.nio.ch.WindowsSelectorImpl.updateSelectedKeys(Unknown Source) 
    at sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source) 
    at sun.nio.ch.SelectorImpl.select(Unknown Source)
    at com.esotericsoftware.kryonet.Client.update(Client.java:219) 
    at com.esotericsoftware.kryonet.Client.run(Client.java:333)
    at java.lang.Thread.run(Unknown Source)
java.lang.OutOfMemoryError: Java heap space
java.lang.OutOfMemoryError: Java heap space
java.lang.OutOfMemoryError: Java heap space
    at java.util.ArrayList.iterator(Unknown Source)
    at sun.nio.ch.WindowsSelectorImpl.updateSelectedKeys(Unknown Source) 
    at sun.nio.ch.WindowsSelectorImpl.doSelect(Unknown Source)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(Unknown Source) 
    at sun.nio.ch.SelectorImpl.select(Unknown Source)
    at com.esotericsoftware.kryonet.Client.update(Client.java:219) 
    at com.esotericsoftware.kryonet.Client.run(Client.java:333)
    at java.lang.Thread.run(Unknown Source)
java.lang.OutOfMemoryError: Java heap space
25:13 INFO: [kryonet] Connection 7 disconnected.

Does someone know why the Java heap gets filled up? Maybe something gets accumulated, but not sure.

Would be great if someone has a clue :) Thanks! 

[Joachim Durchholz]

Hi Lukas,

you'll want to find out what's using up your heap space; the stack trace
is the wrong place to look at, you want a tool like VisualVM (sometimes
called JVisualVM).

For all we know, it could be a memory leak anywhere in your application.

If the data your deserialize originally had lots of shared objects, I
dimly recall that Kryonet may unshare them, and that could cause an
exponential size blowup, or even an infinite one if your data structure
has backlinks.
There was a discussion quite a while about about making Kryonet restore
sharing properties, but I believe it was rejected due to performance
reasons (I may be wrong).

Regards,
Jo

Am 05.06.20 um 15:09 schrieb Lukas S:

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[Lukas S]

Hi Jo,

thanks for your reply :) Highly appreciated! I had to think about it and then I found an accumulation of unprocessed data. 

Regards,

Lukas