RFR: 8199407: Skip Rebuild Remset Phase if there are no rebuild candidates

[Ivan Walulya]

On Mon, 12 Apr 2021 13:27:10 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Hi all,
>> 
>> Please review this change that skips the rebuild remset phase and the associated updates after rebuild, If during Remark, G1 finds that there are no remembered sets to rebuild.
>> 
>> Test: tier1-5
>
> src/hotspot/share/gc/g1/g1ConcurrentMark.cpp line 1962:
> 
>> 1960:   // skip the rebuild remembered set phase
>> 1961:   if (total_selected_for_rebuild() == 0) {
>> 1962:     log_debug(gc, remset, tracking)("Skipping Remembered Set Rebuild. No Regions Selected For Rebuild.");
> 
> Maybe better is `log_debug(gc, marking)` here, somewhat fitting with the other messages when running with `gc+marking=debug`. Also the upper casing the in the second sentence seems weird, `No regions selected for rebuild` seems better (`Remembered Set Rebuild` is the name of that phase, and we do the upper casing for them already. But the second statement seems to be a regular statement)

Thanks, will make both changes

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PR: https://git.openjdk.java.net/jdk/pull/3434