Details
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Sub-task
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Resolution: Delivered
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P4
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22
Description
G1 now reclaims regions that failed evacuation in the next garbage collection.
When there is not enough space to move Java objects from the collection set, young generation regions for example, to some destination area, or that region has been pinned and contains non-movable Java objects (see [JEP 423]), G1 considers that region to have failed evacuation.
Previously, such regions were moved into the old generation as completely full regions, and left lingering for re-examination until the next complete heap analysis, marking, found them to be reclaimable in the next space reclamation phase. Very often, such regions are sparsely populated because only a very few objects were not relocatable or very few objects were actually pinned.
With this change, G1 considers evacuation failed regions as reclaimable beginning with any subsequent garbage collection. If the pause time permits, G1 will evacuate them in addition to the existing collection set.
This can substantially reduce the time to reclaim these mostly empty regions, decreasing heap pressure and the need for garbage collection activity in the presence of evacuation failed regions.
When there is not enough space to move Java objects from the collection set, young generation regions for example, to some destination area, or that region has been pinned and contains non-movable Java objects (see [JEP 423]), G1 considers that region to have failed evacuation.
Previously, such regions were moved into the old generation as completely full regions, and left lingering for re-examination until the next complete heap analysis, marking, found them to be reclaimable in the next space reclamation phase. Very often, such regions are sparsely populated because only a very few objects were not relocatable or very few objects were actually pinned.
With this change, G1 considers evacuation failed regions as reclaimable beginning with any subsequent garbage collection. If the pause time permits, G1 will evacuate them in addition to the existing collection set.
This can substantially reduce the time to reclaim these mostly empty regions, decreasing heap pressure and the need for garbage collection activity in the presence of evacuation failed regions.