Revert Blackbird default; align Jackson to 2.21#21
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…ackson 2.21 The Blackbird default registered in #20 was benched against Jackson 2.17.2, where it showed a ~2x deserialize win. moderne-cli (the primary consumer) and most current openrewrite components have moved to Jackson 2.21, where Blackbird no longer wins on deserialize and *regresses* serialize by ~70% on the real-trace JMH bench (vanilla 317±19 µs vs Blackbird 540±31 µs on a 303 KB GetObject payload — non-overlapping CIs). End-to-end this manifests as visibly slower `mod run` in production after 1.0.8 shipped: BatchVisit p50/p99 times rose 4-12x / 4-65x compared to the 1.0.7 baseline on the JS Applications working set. While here, bump jackson-module-parameter-names from 2.17.2 to 2.21.1 to match what consumers force via their version-alignment rules; this keeps the BOM resolution stable and avoids accidental version skew at runtime. The streaming TokenBuffer-based deserialize from #18 stays — that's the deserialize-side win Blackbird was attempting to chase, already shipped.
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Summary
BlackbirdModuledefault registration shipped in Register Blackbird module by default in JsonMessageFormatter #20 (jsonrpc 1.0.8).jackson-module-parameter-namesfrom 2.17.2 to 2.21.1 to align with the Jackson version consumers (moderne-cli, recent openrewrite/rewrite) force via their build conventions.Why revert Blackbird
The original PR's bench was on Jackson 2.17.2 —
RealTraceBench(replaying a capturedmod runtrace) showed Blackbird at ~2x faster deserialize and ~1.5x serialize. Re-running the same bench against Jackson 2.21.x tells a different story:serialize_maxdeserialize_maxThe serialize regression is real (tight error bars, no CI overlap). End-to-end on
mod run org.openrewrite.node.migrate.upgrade-node-24against the JS Applications working set, BatchVisit p50/p99 went up 4-12x / 4-65x against the pre-Blackbird baseline.We don't yet have a clean answer for why Blackbird 2.21.x regresses serialize while 2.17.2 didn't — Jackson 2.21 likely shifted the reflective-vs-generated-accessor balance — but the data is unambiguous: shipping Blackbird as a default in this Jackson lineage is a net loss for the primary consumer.
Why bump parameter-names
moderne-cliand recentopenrewrite/rewriteforce allcom.fasterxml.jackson*to 2.21.1 via dependency resolution rules. Pinningjackson-module-parameter-namesto 2.17.2 in jsonrpc resolves to the forced 2.21.1 anyway in those consumers, but locally and in any consumer that doesn't force, the 2.17.2 / 2.21.1 mix is the slightly-skewed combo that may explain some of the Blackbird-regression weirdness above. Aligning the pin to 2.21.1 keeps BOM resolution stable.What stays
TokenBuffer-based deserialize introduced in Streaming RawJson deserialize + hot-path cleanups (1.15-1.60x round-trip) #18 stays — that was the deserialize-side win Blackbird was attempting to chase, already shipped.Test plan
./gradlew test)mod run upgrade-node-24against the JS Applications working set with this version and confirm BatchVisit p50/p99 return to the pre-1.0.8 baseline