[SOLVED] com.jme3.util.ReflectionAllocator destroyDirectBuffer SEVERE: Buffer cannot be destroyed: java.nio.DirectByteBuffer

Hey

I’ve tried searching here and otherwise google’in, but came up short. I get this in my logs alot:

Aug 04, 2020 11:27:12 PM com.jme3.util.ReflectionAllocator destroyDirectBuffer
SEVERE: Buffer cannot be destroyed: java.nio.DirectByteBuffer[pos=0 lim=48 cap=48]

I’ve tried switching to LWJGL3 in gradle build like so:

implementation "org.jmonkeyengine:jme3-lwjgl3:$jmeVersion"

wih jmeVersion being 3.4.0

and I have tried adding

add-opens", "java.base/jdk.internal.loader=ALL-UNNAMED"

to the

applicationDefaultJvmArgs = ["-Xmx1024m", "-Xms512m", "-XX:MaxDirectMemorySize=1024m","--add-opens", "java.base/jdk.internal.loader=ALL-UNNAMED"]

I have also tried dispose() after calling in images for use in textures (not sure if that even makes sense to do, but I got that hint in another thread discussing the same messages).

My java versions are as follows:

java --version
openjdk 14.0.2 2020-07-14
OpenJDK Runtime Environment AdoptOpenJDK (build 14.0.2+12)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 14.0.2+12, mixed mode, sharing)

and

javac --version
javac 14.0.2

am I missing anything or any know work arounds I can try?

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I’m curious what code is invoking destroyDirectBuffer(). Could you set a breakpoint using the debugger and print a stack trace?

I think --add-opens and java.base/jdk.internal.ref=ALL-UNNAMED are not separated things.

They should be single argument as below:
"--add-opens=java.base/jdk.internal.ref=ALL-UNNAMED"

For understanding why that error happens please see here:

Edit:

Note, this error wont happen with jme3-lwjgl3 as it does not use ReflectionAllocator.

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So, am I doing something wrong in trying to use lwjgl3 - or I have something else entirely invoking ReflectionAllocator (even though I dont really use reflection directly)

I dont have the source for jme3 set up (I’m just adding the dependencies through gradle), but I’ll try doing that and getting a breakpoint set to dive deeper into this.

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I do not know.

have you tried this as I explained?

Yes, the warning is still there

Trying to add jme3 project (from Github) as dependency:

implementation project(":jme3-core")
//implementation "org.jmonkeyengine:jme3-core:$jmeVersion" 

I get

FAILURE: Build failed with an exception.

  • What went wrong:
    Circular dependency between the following tasks:
    :jme3-core:classes
    ±-- :jme3-core:compileGroovy
    | ±-- :jme3-core:compileJava
    | | — :jme3-core:jar
    | | — :jme3-core:classes ()
    | — :jme3-core:jar (
    )
    — :jme3-core:compileJava (*)

(*) - details omitted (listed previously)

I’m probably missing something really basic about Gradle and sources/projects.

Anyone have a link to a guide I can read on how to set up the dependencies so I can debug them ?

Also, it will print which LWJGL version you are using into the console when you start the app.

For LWJGL2 you should see this:

12:25:00,344 INFO  [LwjglContext] LWJGL 2.9.3 context running on thread jME3 Main

and for LWJGL3

12:33:32,148 INFO  [LwjglContext] LWJGL 3.2.3 build 13 context running on thread main`
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This is written in the log when starting the app:

Aug 05, 2020 10:12:24 AM com.jme3.system.lwjgl.LwjglContext printContextInitInfo
INFO: LWJGL 3.2.3 build 13 context running on thread main

At the very start, I do see this though (not sure its related)

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.jme3.util.ReflectionAllocator (file:…/jmonkeyengine/jme3-core/3.4.0-SNAPSHOT/jme3-core-3.4.0-SNAPSHOT.jar) to method sun.nio.ch.DirectBuffer.cleaner()
WARNING: Please consider reporting this to the maintainers of com.jme3.util.ReflectionAllocator
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

Can you add this into your main method and show us the result?

        // get a RuntimeMXBean reference
        RuntimeMXBean runtimeMxBean = ManagementFactory.getRuntimeMXBean();

        // get the jvm's input arguments as a list of strings
        List<String> listOfArguments = runtimeMxBean.getInputArguments();
        listOfArguments.forEach(s -> System.out.println("ARG:" + s));

Here’s the output:

ARG:-XX:MaxDirectMemorySize=1024m
ARG:–add-opens=java.base/jdk.internal.loader=ALL-UNNAMED
ARG:-Xms512m
ARG:-Xmx1024m
ARG:-Dfile.encoding=windows-1252
ARG:-Duser.country=GB
ARG:-Duser.language=en
ARG:-Duser.variant

Should the line only have 1 dash perhaps? …

Wait…

?

it should be --add-opens=java.base/jdk.internal.ref=ALL-UNNAMED

note the jdk.internal.loader vs jdk.internal.ref

Thank you. That got rid of all the SEVERE warnings. Does that mean its solved or does this just “hide the problem” ?

Solved

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So my original problem was solved by both LWJGL3 and the JVM args. Thank you both for chipping in.

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I mean by setting this JVM arg you can keep using LWJGL2 if that is what you want.

Edit:
Marked the thread solved.

2 Likes