Fix Unsafe string paths when -XX:-CompactStrings is used#1
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Detect at class init whether JDK compact strings are enabled by checking the internal byte[] length of a known ASCII string. Guard all Unsafe string fast paths (writeString, writeRawString, readString) with this flag so they fall back to safe standard library methods when compact strings are disabled and the internal representation is UTF-16. Add a surefire execution that re-runs all tests with -XX:-CompactStrings.
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lhotari
approved these changes
Mar 17, 2026
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Summary
writeString,writeRawString,readString) so they fall back to safe standard library methods when compact strings are disabled (-XX:-CompactStrings)-XX:-CompactStringsto prevent regressionsContext
Reported by @lhotari in apache/pulsar#25332 — the optimized String handling assumes compact strings (LATIN1 coder) are always enabled, which breaks when
-XX:-CompactStringsis used and the internalString.valuebyte array uses UTF-16 encoding.Test plan
-XX:-CompactStrings