RFR: 8289071: Compute stub sizes outside of locks

[Yi-Fan Tsai]

8289071: Compute stub sizes outside of locks

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Commit messages:
 - 8289071: Compute stub sizes outside of locks

Changes: https://git.openjdk.org/jdk/pull/9266/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9266&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289071
  Stats: 25 lines in 2 files changed: 8 ins; 7 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/9266.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9266/head:pull/9266

PR: https://git.openjdk.org/jdk/pull/9266