RFR: 8329203: Parallel: Investigate Mark-Compact for Full GC to decrease memory usage

[Albert Mingkun Yang]

On Mon, 6 May 2024 11:15:08 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> Parallel GC has no such conceps of regions.

Parallel full-gc does use "regions", `ParallelCompactData::RegionData`.

> My idea was to divide into regions for the purpose of the full-GC and deal with overlapping objects somehow, maybe by using a block-offset-table. But I haven't spent too much thought on it, so far.

That's how existing full-gc works (e.g. `partial_obj_addr` for overlapping objs) and the new implementation doesn't touch/change that part. The most significant change is doing new-addr-calculation and remapping before compaction; hence, these two new phases.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/19101#issuecomment-2095799721