JDK-8180175 : ObjectSynchronizer only needs to iterate in-use monitors
- Type: Enhancement
- Component: hotspot
- Sub-Component: runtime
- Affected Version: 9,10
- Priority: P3
- Status: Resolved
- Resolution: Fixed
- OS: generic
- CPU: generic
- Submitted: 2017-05-11
- Updated: 2019-05-22
- Resolved: 2017-05-18
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| JDK 10 |
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10 b21Fixed  |
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Description
ObjectSynchronizer::oops_do() currently iterates all monitor blocks, even free ones. With -XX:+MonitorInUseLists, each thread has its own in-use monitors list, and ObjectSynchronizer has a global gOmInUseList for moribund threads. Iterating over in-use monitors only significantly inmproves scanning time for monitors, because it avoids scanning free blocks, improves caching (no padding, and better chances to have thread-local oops in cache already).