docs: rewrite IMPLEMENTING_JRES.md for BaseJRE pattern#1339
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stokpop merged 6 commits intoJul 9, 2026
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PR cloudfoundry#1288 refactored all standard JREs to embed BaseJRE (14 lines each), but the guide still showed the old 100+ line manual implementation with explicit Supply()/Finalize() boilerplate. Rewrite to document the actual pattern: newBaseJRE() + optional extraFinalizeOpts. Removes sections on manual memory calculator and JVMKill integration (now internal to BaseJRE). Adds variation-point table and examples for all three patterns (standard, exact-dir, error-hint).
…ooting Rebalances the IMPLEMENTING_JRES.md rewrite — adds back lean sections for: - Helper function reference table (GetJREVersion, WriteJavaOpts, etc.) - profile.d script output example - Memory calculator: runtime output and user customization env vars - JVMKill: purpose, heap dump / volume service binding - Troubleshooting: JAVA_HOME, memory calculator, version resolution
- Use Java 21 in version examples and profile.d output - Prefer JBP_CONFIG_<JRE>_JRE for memory calculator config (covers stack_threads, class_count, headroom) - Note MEMORY_CALCULATOR_* env vars take precedence but don't cover class_count - Add stack_threads/class_count/headroom descriptions
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Pull request overview
This PR rewrites docs/IMPLEMENTING_JRES.md to document the newer BaseJRE template-method pattern (introduced in #1288) and remove the older long-form “manual boilerplate” JRE provider implementation guidance.
Changes:
- Replaces large per-provider implementation walkthroughs with a
BaseJREvariation-points model and a short 3-step “how to add a JRE” guide. - Adds concise examples for standard prefix matching, exact-dir matching, and install-error hints.
- Updates operational reference sections (memory calculator, JVMKill, troubleshooting) and refreshes examples to Java 21.
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…NTING_JRES.md Addresses PR review: - Add missing MemoryCalculatorCommand() to the jres.JRE interface excerpt. - Add the missing `type MinimalJRE` so the no-extra-opts example compiles. - Correct detection/version docs to match DetectJREByEnv/GetJREVersion: the documented JBP_CONFIG_<NAME>_JRE name (recommended) or the auto-generated JBP_CONFIG_<KEY> alias. JBP_CONFIG_COMPONENTS is deprecated and unused for selection; there is no BP_JAVA_<JREKEY> variable.
…v var Copilot review: - stack_threads default is 250 (DefaultStackThreads in src/java/jres/jre.go), not 200 - troubleshooting resolution order used JBP_CONFIG_<KEY>_JRE; the code checks the documented JBP_CONFIG_<NAME>_JRE name or the auto-generated JBP_CONFIG_<KEY> alias
kiril-keranov
approved these changes
Jul 9, 2026
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Summary
IMPLEMENTING_JRES.mdto reflect theBaseJREtemplate-method pattern introduced in PR refactor: extract BaseJRE to eliminate duplication across standard JRE providers #1288What changed
BaseJREautomatically)BaseJREvariation points table, 3-step implementation guide, lean examples for standard/exact-dir/error-hint patternsJBP_CONFIG_<JRE>_JREas preferred (coversstack_threads,class_count,headroom) with a note thatMEMORY_CALCULATOR_*env vars override but don't coverclass_countRelated
Follows #1288 (
BaseJRErefactor that this doc now describes)Please review if complete or must be extended.