GROOVY-12142 backport: Stop pinning container class loaders: remove PIC-Cleane…

[paulk-asert]

…r and DFA-cache-cleaner threads, restore the ClassValue escape hatch

A Groovy copy deployed per webapp (the common Tomcat/WEB-INF/lib topology) permanently pinned its class loader, growing metaspace on every parallel (re)deployment. Three independent pins:

1. PIC-Cleaner: linking any indy call site started a never-terminating daemon thread from CacheableCallSite's static initializer, pinning the defining loader and capturing the creating context's protection domains. Stale PIC entries are now swept inline — both callers already hold the lruCache monitor and the cache is bounded (8), so the sweep is trivial; the groovy.indy.callsite.cleaner.inline flag (GROOVY-12092) is gone along with the thread it toggled, which also removes the parked-thread false positive it existed to avoid.

2. DFA-cache-cleaner: each AtnManager started a never-terminating reference-queue thread whose catch-all swallowed even interrupts. The softly referenced AtnWrapper is a GC canary; its collection is now detected on the parse path when the soft reference reads null, clearing the shared DFA cache at the next parse instead of at GC time — no queue, no thread.

3. java.lang.ClassValue associations on immortal (bootstrap) classes never release their value's class loader (JDK-8136353), so one dynamic dispatch on e.g. String pinned the loader. The groovy.use.classvalue=false escape hatch (present through 4.x, lost in the GROOVY-11520 collections cleanup) is restored, with the fallback rebuilt on ManagedIdentityConcurrentMap (~40 lines) rather than the removed deprecated collections. Default stays ClassValue.

With 1+2 fixed, a dropped loader is collectable either with the flag or with a shutdown sweep over ClassInfo.getAllClassInfo() calling ClassInfo.remove — both verified by classloader-churn harness against the rebuilt jar; out-of-the-box default config still requires one of the two (the JVM bug is not ours to fix).

[codecov-commenter]

Codecov Report

❌ Patch coverage is 78.94737% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.2876%. Comparing base (514e66f) to head (dfbac1e).

Files with missing lines	Patch %	Lines
...aus/groovy/reflection/GroovyClassValueFactory.java	50.0000%	1 Missing and 1 partial ⚠️
.../parser/antlr4/internal/atnmanager/AtnManager.java	85.7143%	0 Missing and 1 partial ⚠️
...codehaus/groovy/vmplugin/v8/CacheableCallSite.java	0.0000%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@                  Coverage Diff                   @@
##             GROOVY_5_1_X      #2800        +/-   ##
======================================================
+ Coverage         67.2715%   67.2876%   +0.0160%     
- Complexity          29631      29639         +8     
======================================================
  Files                1383       1384         +1     
  Lines              117109     117090        -19     
  Branches            20596      20595         -1     
======================================================
+ Hits                78781      78787         +6     
+ Misses              31777      31753        -24     
+ Partials             6551       6550         -1     

Files with missing lines	Coverage Δ
...us/groovy/reflection/GroovyClassValueMapBased.java	100.0000% <100.0000%> (ø)
.../parser/antlr4/internal/atnmanager/AtnManager.java	71.7949% <85.7143%> (+18.9647%)	⬆️
...codehaus/groovy/vmplugin/v8/CacheableCallSite.java	94.0000% <0.0000%> (+17.0769%)	⬆️
...aus/groovy/reflection/GroovyClassValueFactory.java	40.0000% <50.0000%> (-10.0000%)	⬇️

... and 11 files with indirect coverage changes

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