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🟢 Java Benchmark SLOs — All performance SLOs passed
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Kafka / producer-benchmarkParameters
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SummaryFound 1 performance improvements and 0 performance regressions! Performance is the same for 2 metrics, 0 unstable metrics.
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Kafka / consumer-benchmarkParameters
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SummaryFound 0 performance improvements and 0 performance regressions! Performance is the same for 3 metrics, 0 unstable metrics. See unchanged results
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MsgPackDatastreamsPayloadWriter held a 512 KiB GrowableBuffer for the tracer's lifetime, allocated when DefaultDataStreamsMonitoring is built - even with Data Streams off, where it was never written to. It was a G1 humongous object on heaps up to about 2 GB. It now uses a ChunkedStreamingBuffer with a 5 MiB cap: nothing is allocated until the first payload, so DSM off costs no buffer, and a payload of a few KB keeps a few KB. A payload over the cap is dropped with a debug log instead of growing without bound. Sink loses its single-buffer default, which only this writer used. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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What Does This Do
Moves the Data Streams Monitoring payload writer (
MsgPackDatastreamsPayloadWriter) off its 512 KiBGrowableBufferand onto the chunked buffer. Stacked on #13097 ("Serialize client stats payloads into a chunked buffer"), which adds the small-chunk default and makesSinktake a payload as chunks.ChunkedStreamingBufferwith a 5 MiB cap.mark()reports the drop.Sink.acceptdefault that Serialize client stats payloads into a chunked buffer #13097 kept for this writer.Motivation
DefaultDataStreamsMonitoringbuilds this writer whether or not Data Streams is enabled, and the writer allocated its 512 KiB buffer right away. With DSM off (the default), the buffer was never written to: in a heap dump of Spring PetClinic it was all zeros.512 KiB plus the 16-byte array header is just over half a 1 MB G1 region, so it was a humongous object on heaps up to about 2 GB, pinned in old gen for the tracer's lifetime. It was one of the five humongous regions the agent held after #13096. With #13097, three remain, all from the agent jar's central directory (APMLP-2161). The full measurement is in #13097.
This is the memory side of the same pattern as the recent DSM guard PRs: work done for Data Streams while it's off.
Additional Notes
MsgPackDatastreamsPayloadWriterTestcovers the cap: a payload one byte over is dropped without throwing, and one at the cap is sent.Jira ticket: APMLP-2159
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