[ISSUE #10976] Reduce per-message allocation on the proxy gRPC path

[wang-jiahua]

Which Issue(s) This PR Fixes

Fixes #10976

Brief Description

Two per-message allocation sources removed on the proxy gRPC path:

1. BinaryUtil.calculateMd5 performed a MessageDigest.getInstance("MD5") provider lookup and created a fresh digest on every call; GrpcConverter#buildSystemProperties hits this for every message delivered to a gRPC consumer. The digest is now kept per thread in a ThreadLocal (MessageDigest is not thread safe) and reset() before each use.
2. SendMessageActivity#buildMessageProperty (and validateMessageGroup) called getBytes(StandardCharsets.UTF_8) on every user-property key/value, the tag, each message key, and the message group, only to read .length for size validation. A new utf8Length(String) helper computes the encoded length without materializing the array, matching String.getBytes(UTF_8).length exactly (including the single-byte replacement for unpaired surrogates); the five call sites now use it.

How Did You Test This Change?

• BinaryUtilTest (new): result matches a fresh MessageDigest, and stays stable across interleaved calls on the reused per-thread instance.
• SendMessageActivityTest#testUtf8Length: sample-by-sample equality with getBytes(UTF_8).length covering ASCII, CJK, supplementary (emoji), and unpaired surrogates; full class 12/12.
• Dedicated gRPC A/B on a 4-node cluster: proxy in cluster mode plus a loopback load tool built on rocketmq-client-java 5.0.7 (producer 8 threads with multi-byte user properties exercising utf8Length; SimpleConsumer 4 threads exercising the digest path), swapping the proxy's rocketmq-common/rocketmq-proxy jars per arm, 3 interleaved trials plus 1 reversed-order control: ~9.4k send TPS / ~5.1k consume TPS with zero failures in all 8 arms; proxy young GC counts showed a pure positional artifact (first arm of each pair always 9, second always 10, independent of the jar — confirmed by the reversed-order control), i.e. parity after correction. No regression; the allocation saving is below GC-count resolution, so this is a cleanup-level optimization on the proxy hot path.

[Copilot]

Pull request overview

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Reduces per-message allocations on the proxy gRPC hot path by reusing MD5 MessageDigest instances per thread and validating UTF-8 byte lengths without allocating intermediate byte arrays.

Changes:

• Reworked BinaryUtil.calculateMd5 to use a per-thread MessageDigest (ThreadLocal) and added tests for stability/correctness.
• Replaced multiple String.getBytes(UTF_8).length validations with a zero-allocation utf8Length(String) helper.
• Added unit tests covering UTF-8 length calculations across ASCII, BMP, supplementary characters, and malformed surrogate cases.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
proxy/src/main/java/org/apache/rocketmq/proxy/grpc/v2/producer/SendMessageActivity.java	Introduces utf8Length and switches size checks to avoid byte[] allocations.
proxy/src/test/java/org/apache/rocketmq/proxy/grpc/v2/producer/SendMessageActivityTest.java	Adds direct unit test coverage for utf8Length equality vs getBytes(UTF_8).length.
common/src/main/java/org/apache/rocketmq/common/utils/BinaryUtil.java	Uses a per-thread cached MD5 digest to avoid repeated provider lookup/allocation.
common/src/test/java/org/apache/rocketmq/common/utils/BinaryUtilTest.java	Adds tests to verify MD5 correctness and that per-thread reuse resets between calls.

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[RockteMQ-AI]

Summary

This PR eliminates two per-message allocation sources on the proxy gRPC path: (1) MessageDigest.getInstance("MD5") provider lookup on every calculateMd5 call, replaced with a ThreadLocal<MessageDigest> that is reset() before each use; (2) str.getBytes(UTF_8).length for measuring UTF-8 encoded size, replaced with a branch-based utf8Length() that computes the byte count without allocating a temporary array.

Both changes are correct and well-motivated. The ThreadLocal pattern for MessageDigest is standard practice for non-thread-safe reusable objects, and reset() is properly called before each use. The utf8Length() implementation correctly handles all cases: ASCII, BMP, supplementary characters (surrogate pairs), and unpaired surrogates (matching Java's getBytes(UTF_8) replacement behavior). Tests cover all edge cases including interleaved payloads to verify the ThreadLocal does not corrupt results.

LGTM — clean, focused performance optimization with solid test coverage.

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Automated review by github-manager-bot

[codecov-commenter]

Codecov Report

❌ Patch coverage is 84.61538% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.52%. Comparing base (e348efa) to head (a7df129).

Files with missing lines	Patch %	Lines
...mq/proxy/grpc/v2/producer/SendMessageActivity.java	85.71%	1 Missing and 2 partials ⚠️
...a/org/apache/rocketmq/common/utils/BinaryUtil.java	80.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #10977      +/-   ##
=============================================
- Coverage      48.58%   48.52%   -0.06%     
+ Complexity     13676    13665      -11     
=============================================
  Files           1381     1381              
  Lines         101475   101492      +17     
  Branches       13190    13196       +6     
=============================================
- Hits           49299    49248      -51     
- Misses         46174    46222      +48     
- Partials        6002     6022      +20     

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[RockteMQ-AI]

Summary

Reduces per-message allocation on the proxy gRPC path by (1) caching MessageDigest in a ThreadLocal in BinaryUtil.calculateMd5 and (2) replacing String.getBytes(UTF_8).length with a zero-allocation utf8Length() in SendMessageActivity.

Changes look correct:

• ThreadLocal<MessageDigest> with reset() before each use is the right pattern for non-thread-safe digest instances
• Test interleaves calls to verify reset stability — good coverage
• utf8Length() avoids byte array allocation for size validation on the hot path

Minor note: the .gitignore additions (.qoder/, profiling-tools/, etc.) appear to be local dev artifacts — consider whether these belong in a project-wide .gitignore.

LGTM.

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Automated review by github-manager-bot