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[azure-core] Fix partial InputStream response buffering - #50837
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Alan Zimmer (alzimmermsft) merged 4 commits intoOct 26, 2026
Merged
Alan Zimmer (alzimmermsft) merged 4 commits into
Alan Zimmer (alzimmermsft) merged 4 commits into
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Emit partial response data once no additional bytes are immediately available, while opportunistically coalescing buffered bytes up to the configured chunk size. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 7eaead83-8f9e-4c68-9958-ad8e66668356
Verify JDK and OkHttp clients deliver a flushed SSE frame before the response reaches EOF. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 7eaead83-8f9e-4c68-9958-ad8e66668356
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Xiaofei Cao (XiaofeiCao)
changed the title
Xiaofei Cao (XiaofeiCao)
marked this pull request as ready for review
October 16, 2026 09:34
Xiaofei Cao (XiaofeiCao)
requested review from
a team,
Jonathan Giles (JonathanGiles),
Alan Zimmer (alzimmermsft) and
vcolin7
as code owners
October 16, 2026 09:34
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🟢 Approval recommended
The localized buffering correction has targeted unit and HTTP regression coverage, with no identified blocking defects.
0 open findings
What changed in this PR
Fixes Azure Core’s InputStream response buffering so flushed partial data can reach streaming consumers without waiting for a full chunk or EOF.
Changes:
- Limits additional reads to immediately available bytes.
- Adds unit and shared HTTP regression coverage for partial responses.
- Documents the streaming fix in the changelog.
| File | Description |
|---|---|
| sdk/core/azure-core/src/test/java/com/azure/core/validation/http/HttpClientTestsServer.java | Adds a flushed response with delayed completion. |
| sdk/core/azure-core/src/test/java/com/azure/core/validation/http/HttpClientTests.java | Verifies early delivery through sync and async clients. |
| sdk/core/azure-core/src/test/java/com/azure/core/util/FluxUtilTest.java | Tests partial reads before stream completion. |
| sdk/core/azure-core/src/main/java/com/azure/core/util/FluxUtil.java | Emits partial buffers without waiting to fill them. |
| sdk/core/azure-core/CHANGELOG.md | Records the streaming behavior fix. |
🧠 Review effort: Balanced
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 7eaead83-8f9e-4c68-9958-ad8e66668356
Alan Zimmer (alzimmermsft)
approved these changes
Oct 19, 2026
Alan Zimmer (alzimmermsft)
approved these changes
Oct 26, 2026
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Description
Bug
FluxUtil.toFluxByteBuffercontinues reading until its configured chunk is full or EOF is reached. A small flushed response chunk is therefore withheld while the next read blocks, which can stall long-lived streams such as SSE.The bug affects JDK sync and OkHttp sync/async response streaming. JDK async, Netty, and Vert.x do not have this issue.
Azure Search #50648 consumes streaming
BinaryDatathroughbody.toFluxByteBuffer()for async APIs andbody.toStream()for sync APIs.JDK sync converts its response
InputStreamthroughFluxUtil.toFluxByteBuffer, while OkHttp sync/async useFluxUtil.toFluxByteBuffer(responseBody.byteStream(), 8192). JDK async uses the JDK publisher directly, Netty uses Reactor NettyByteBufFlux, and Vert.x usesBuffercallbacks.Fix
Perform one demand-driven blocking read, coalesce only bytes reported as immediately available, and emit the partial buffer without waiting for the configured chunk to fill.
This fixes JDK sync and OkHttp sync/async while preserving the existing behavior of JDK async, Netty, and Vert.x.
Validation
Added unit and shared HTTP-client coverage verifying flushed partial responses arrive before EOF. Azure Core tests passed (11,891 tests, 3 skipped), including targeted JDK and OkHttp sync/async regressions. Checkstyle and SpotBugs also passed.
All SDK Contribution checklist:
General Guidelines and Best Practices
Testing Guidelines