RFR: 8257774: G1: Trigger collect when free region count drops below threshold to prevent evacuation failures [v3]

[Aditya Mandaleeka]

On Thu, 15 Apr 2021 10:00:11 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Aditya Mandaleeka has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix format specifiers.
>
> During some internal discussion with the people that had looked at the change a bit, we agreed that the additional `attempt_lock_free_first` parameter is very ugly and complicates the code a lot.
> 
> [Here](https://github.com/tschatzl/jdk/commit/6c10cb3e6d71fcbb487385e23ea77d3c29f31b4d) is an attempt to remove this parameter by an explicit method that allocates using a new region. It does look nicer to me. No testing has been performed, just to see how it would look like.
> 
> The change also removes that `use_retained_region_if_available` parameter form the lock-free `attempt_allocation` call. With your recent changes, all paths should try it (there has been a case where this was not true, but I think that one was errorneous), so I removed that parameter too.
> 
> Please also merge with latest once more, the change is a bit out of date.

Thanks @tschatzl, will review the feedback, re-test, and update the PR (likely sometime next week).

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

PR: https://git.openjdk.java.net/jdk/pull/3143