[GR-71271] Don't do an incremental GC before a forced full GC with CompactingOldGen. #12513
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When a full GC is requested via
System.gc()or at the end of a libgraal compilation, the policy is asked whether to do an incremental collection first, but does not have the information that a full GC will happen either way. In case ofCompactingOldGen, it would prefer to do the full GC immediately, which this change enables.This change can make a difference with benchmarks, which commonly trigger GC between iterations. While the collections are excluded from reported iteration times, they typically are not excluded from footprint measurements. Future policy decisions can also be negatively impacted by the unnecessary collections.
The change does not have an impact with
CopyingOldGen, which is the current default. WithCompactingOldGen, it leads to significant improvements for scaladoc and kiama, and potentially lusearch, sunflow and scala-doku.