(groovy) 02/02: GROOVY-12281: quantify the cost of groovy.use.classvalue=false in the guide

[pa...@apache.org]

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paulk-asert pushed a commit to branch groovy12281
in repository https://gitbox.apache.org/repos/asf/groovy.git

commit 7ec24cc22186a176312bddb33d3699112aafd6b0
Author: Paul King <pa...@asert.com.au>
AuthorDate: Wed Aug 19 14:07:40 2026 +1000

    GROOVY-12281: quantify the cost of groovy.use.classvalue=false in the guide
    
    The escape hatch's trade-off was described as not measurable for most
    applications. Measured (57 classic-dispatch JMH benchmarks): +4.8%
    geomean with hot platform-receiver idioms up to ~1.4x, while compile
    time is within 1%. The guide now states those numbers so integrators
    can decide with their own workload in mind.
    
    Co-Authored-By: Claude Fable 5 <no...@anthropic.com>
---
 src/spec/doc/guide-integrating.adoc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/spec/doc/guide-integrating.adoc b/src/spec/doc/guide-integrating.adoc
index a7f930091f..695e7f53d6 100644
--- a/src/spec/doc/guide-integrating.adoc
+++ b/src/spec/doc/guide-integrating.adoc
@@ -397,7 +397,11 @@ Two supported measures release the class loader; either one suffices:
 
 * Start the JVM with `-Dgroovy.use.classvalue=false`. Groovy then stores the associations in a
   weak-key map instead of `ClassValue`. The trade-off is a hash lookup where `ClassValue` has a
-  per-class fast path; for most applications the difference is not measurable.
+  per-class fast path. Compilation speed is unaffected (within 1% in our measurements), and for
+  applications that are not dispatch-heavy the difference is unlikely to be noticed; heavily
+  dynamic code, however, can see a few percent overall, with hot dynamic idioms on JDK-class
+  receivers (string coercions, ranges, safe navigation, map property access) up to roughly
+  1.4 times slower. Measure with your own workload if dispatch performance matters.
 * Clean up explicitly when the application is discarded (for example from
   `ServletContextListener#contextDestroyed`):
 +