Results 2 issues of Doug Lea

This set of changes address causes of poor utilization with small numbers of cores due to overly aggressive contention avoidance. A number of further adjustments were needed to still avoid...

rfr
core-libs

Changes signal filtering to avoid possible starvation --------- ### Progress - [ ] Change must be properly reviewed (1 review required, with at least 1 [Reviewer](https://openjdk.org/bylaws#reviewer)) - [x] Change must...

rfr
core-libs