8357959: (bf) ByteBuffer.allocateDirect initialization can result in large TTSP spikes #118
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Contributor
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This seems to be missing the key change in src/java.base/share/classes/java/nio/Direct-X-Buffer.java.template to actually use the new code, so I think if you run the reproducer you will not see any improvement. |
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olivergillespie
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Sep 16, 2025
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Be aware that Corretto commit metadata should follow the OpenJDK one. Current commit would get committed with |
shipilev
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…large TTSP spikes Backport-of: e5ce5c57c83972ff52758a804c942986cab74ca7
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Just need to run the reproducer again with the merged file changes |
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ByteBuffer.allocateDirect initialization can result in large TTSP spikes
This backport adapts the JDK 26 improvement for ByteBuffer.allocateDirect initialization to reduce TTSP spikes. Minor conflict in template resolved manually to preserve 2023 copyright.
Description
This is a backport of a change made in openjdk/jdk#25487
This is a performance change that prevents large safe point pauses during ByteBuffer.allocateDirect.
Related issues
Backport of openjdk/jdk#25487
Motivation and context
This change has been added to JDK26 for a few months, and back ported to JDK25. This is a large performance gain, which would be nice to have in the 21 jdk.
How has this been tested?
This has been tested via unit test, and a reproducer run shows the performance gains from ~1s to < 1ms
https://gist.github.com/rk-kmr/be4322b72a14ae04aeefc0260c01acf6
Platform information
None
Additional context