GROOVY-10307: Add targeted JMH benchmarks for SwitchPoint invalidation

[jamesfredley]

Summary

Adds three new JMH benchmark classes in org.apache.groovy.perf.grails that reproduce the real-world invokedynamic performance regression observed in Grails 7 applications (GROOVY-10307).

Benchmark Classes

CallSiteInvalidationBench (11 benchmarks)

Tests the core SwitchPoint invalidation mechanism - the root cause of the regression. Demonstrates that modifying ANY metaclass triggers global invalidation affecting ALL call sites:

• Cross-type invalidation at 3 frequencies (every 100/1000/10000 iterations)
• Same-type invalidation for comparison
• Multiple call sites scaling (5 concurrent call sites)
• Burst-then-steady-state simulating framework startup

Key result: baselineHotLoop (0.49ms) vs crossTypeInvalidationEvery1000 (467ms) = ~950x overhead

MetaclassVariationBench (9 benchmarks)

Tests GORM-like patterns where domain classes get per-instance ExpandoMetaClass enhancements:

• Shared vs per-instance metaclass dispatch
• Multi-class startup simulation (4 domain types enhanced in sequence)
• Dynamic finder calls via static metaclass injection
• Per-instance EMC with ongoing churn (worst case)

Key result: baselineSharedMetaclass (2.0ms) vs perInstanceMetaclass (420ms) = ~207x overhead

GrailsWorkloadBench (14 benchmarks)

Tests patterns extracted from the grails7-performance-regression demo app's PerformanceTestService:

• Collection closure chains (.findAll{}.collect{}.groupBy{}.collectEntries{})
• Spread operator (employees*.firstName)
• Nested closure delegation (3-level criteria-like DSL)
• GString interpolation with dynamic property access
• Dynamic property by name (this."$field")
• Project metrics aggregation (.count{}, .sum{}, map building)
• Full analysis combining all patterns

Key result: baselineCollectionClosureChain (199ms) vs with invalidation (1631ms) = ~8.2x overhead (matches demo app's observed 8.2x bootRun regression)

Running

# All new benchmarks
./gradlew :performance:jmh -PbenchInclude="CallSiteInvalidation|MetaclassVariation|GrailsWorkload"

# Individual benchmark class
./gradlew :performance:jmh -PbenchInclude=CallSiteInvalidation

Related

• GROOVY-10307
• grails-core #15293
• Demo app showing 5-8x regression
• PR GROOVY-10307: Groovy 6 - Improve invokedynamic performance with optimized caching #2377 (SwitchPoint guard optimization - benchmarked here)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.7468%. Comparing base (8a40250) to head (1af1c45).

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2390        +/-   ##
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+ Coverage     66.7450%   66.7468%   +0.0017%     
- Complexity      29848      29849         +1     
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  Files            1382       1382                
  Lines          116130     116130                
  Branches        20471      20471                
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+ Hits            77511      77513         +2     
+ Misses          32286      32284         -2     
  Partials         6333       6333                

see 5 files with indirect coverage changes

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[Copilot]

Pull request overview

Adds new JMH benchmarks under org.apache.groovy.perf.grails to reproduce and quantify the invokedynamic regression related to global SwitchPoint invalidation seen in Grails 7 apps (GROOVY-10307), focusing on metaclass churn and Grails-like workloads.

Changes:

• Introduces CallSiteInvalidationBench to measure cross-type vs same-type invalidation and multi-call-site scaling.
• Introduces MetaclassVariationBench to model GORM-like per-instance ExpandoMetaClass behavior and static metaclass injection patterns.
• Introduces GrailsWorkloadBench to model higher-level Grails workload patterns (closure chains, delegation, GStrings, dynamic property access) with periodic invalidation.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
subprojects/performance/src/jmh/groovy/org/apache/groovy/perf/grails/CallSiteInvalidationBench.groovy	New focused benchmarks for SwitchPoint invalidation impact on hot call sites.
subprojects/performance/src/jmh/groovy/org/apache/groovy/perf/grails/MetaclassVariationBench.groovy	New benchmarks for shared vs per-instance metaclass dispatch and GORM-like injection patterns.
subprojects/performance/src/jmh/groovy/org/apache/groovy/perf/grails/GrailsWorkloadBench.groovy	New workload-style benchmarks derived from Grails demo regression patterns, with/without invalidation.

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