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Posted to issues@flink.apache.org by "Stephan Ewen (Jira)" <ji...@apache.org> on 2020/01/31 14:05:00 UTC
[jira] [Commented] (FLINK-15094) Warning about using private
constructor of java.nio.DirectByteBuffer in Java 11
[ https://issues.apache.org/jira/browse/FLINK-15094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17027523#comment-17027523 ]
Stephan Ewen commented on FLINK-15094:
--------------------------------------
I did some research about how netty handles this, and it seems that with Java 9+, they simply go with DirectByteBuffers, meaning there is no way to allocate the memory without
- either contributing to MaxDirectMemory
- or getting these mean warnings
- or separating MemorySegments completely from DirectByteBuffer (
Concerning the last point: We can get the network stack free of MemorySegment, but we need MemorySegment/DirectByteBuffer interplay for batch algorithm spilling).
> Warning about using private constructor of java.nio.DirectByteBuffer in Java 11
> -------------------------------------------------------------------------------
>
> Key: FLINK-15094
> URL: https://issues.apache.org/jira/browse/FLINK-15094
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Task
> Reporter: Andrey Zagrebin
> Priority: Major
>
> The unsafe off-heap in [FLINK-13985|https://jira.apache.org/jira/browse/FLINK-13985] was implemented by hacking into a private constructor of java.nio.DirectByteBuffer. This causes undesirable warnings in Java 11:
> {code:java}
> WARNING: An illegal reflective access operation has occurred
> WARNING: Illegal reflective access by org.apache.flink.core.memory.MemoryUtils (file:/C:/Development/repos/flink/flink-core/target/classes/) to constructor java.nio.DirectByteBuffer(long,int)
> WARNING: Please consider reporting this to the maintainers of org.apache.flink.core.memory.MemoryUtils
> 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{code}
> We should look into this, confirm that it is harmless and try to silence it to avoid confusion for users.
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