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Support @WithConfig on IBM J9 8 / OpenJ9 / Semeru 11 JVMs - #11388
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ByteBuddy retransformation silently fails on IBM J9 / OpenJ9 / Semeru, leaving `InstrumenterConfig.INSTANCE` / `Config.INSTANCE` as `private static final`. `rebuildConfig()`'s `Field.set(null, ...)` then throws for every test in the class — including ones with no `@WithConfig` at all: ``` org.opentest4j.AssertionFailedError: expected: <true> but was: <false> at WithConfigExtension.checkWritable(WithConfigExtension.java:331) at WithConfigExtension.checkConfigTransformation(...:324) at WithConfigExtension.beforeAll(...:91) Suppressed: java.lang.AssertionError: Failed to rebuild config at WithConfigExtension.rebuildConfig(...:295) Caused by: java.lang.IllegalAccessException: ... InstrumenterConfig with modifiers "private static final" at java.lang.reflect.Field.set(Field.java:784) at WithConfigExtension.rebuildConfig(...:291) ``` This commit keep ByteBuddy as the primary mechanism to transform bytecode bit adds a `sun.misc.Unsafe`-based fallback: * `makeConfigInstanceModifiable()` checks the actual field modifiers and picks `WriteMode.REFLECTION` when retransformation worked, or `WriteMode.UNSAFE` otherwise. * The Unsafe mechanism is encapsulated in a `UnsafeFieldWriter` that handle updating the field value via `Unsafe::putObjectVolatile`. * Unsafe is resolved lazily and propagates `ReflectiveOperationException` so a JVM without `sun.misc.Unsafe` lands in the existing `configModificationFailed` branch. * `ConfigInstrumentationFailedListener` now flags failures for `InstrumenterConfig` as well, not only `Config`. [ci: NON_DEFAULT_JVMS]
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bric3
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May 19, 2026
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Superseded by #11397 |
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What Does This Do
Fallback to unsafe when retransformation fail on old IBM J9 / Semeru 11 JVMs.
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