JDK-8234205 : Release Note: Disabled Biased-locking and Deprecated Biased-locking Flags
  • Type: Sub-task
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: 15
  • Priority: P4
  • Status: Closed
  • Resolution: Delivered
  • Submitted: 2019-11-15
  • Updated: 2021-05-14
  • Resolved: 2020-06-08
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JDK 15
15Resolved
Description
Biased locking has been disabled by default in this release. In addition, the VM option `UseBiasedLocking` along with the VM options `BiasedLockingStartupDelay`, `BiasedLockingBulkRebiasThreshold`, `BiasedLockingBulkRevokeThreshold`, `BiasedLockingDecayTime` and `UseOptoBiasInlining` have been deprecated. The options will continue to work as intended but will generate a deprecation warning when they are used.

Biased locking might affect performance on applications that exhibit significant amounts of uncontended synchronization, such as applications that rely on older Java Collections APIs that synchronize on every access. `Hashtable` and `Vector` are examples of these APIs. Use `-XX:+BiasedLocking` on the command line to re-enable biased locking. Report any significant performance regressions to Oracle with biased locking disabled.