Integrated: 8304809: Remove develop flag G1ExitOnExpansionFailure

[Thomas Schatzl]

On Fri, 24 Mar 2023 12:02:03 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   please review this removal of the `G1ExitOnExpansionFailure` develop flag. This flag has apparently been there for a long time to better diagnose issues when committing regions fails. Which in itself isn't very useful, as it's a `develop` flag and disabled by default. However @albertnetymk made me aware that this is actually dead code: after JDK8u45 or so, when the heap expansion code has been rewritten, failure to commit will already exit the VM (in `G1PageBasedVirtualSpace` all commit related methods do call `os::commit_memory_or_exit`), so `expanded_by` must always be non-zero. The else-part will never be executed, so can be removed.
> 
> Just in case I added an `assert` to check that; testing tier1-5 with changes that do much more committing could not find any related issue. In the product, afaict getting here with `expanded_by` isn't disastrous either, this would only be a slightly expensive nop telling subsystems that nothing changed.
> 
> Testing: tier1-5, gha
> 
> Thanks,
>   Thomas

This pull request has now been integrated.

Changeset: 4acf20df
Author:    Thomas Schatzl <tschatzl at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/4acf20df7b4729dbf1b6fbab8a94d84c76437031
Stats:     20 lines in 2 files changed: 0 ins; 13 del; 7 mod

8304809: Remove develop flag G1ExitOnExpansionFailure

Reviewed-by: ayang, kbarrett

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PR: https://git.openjdk.org/jdk/pull/13174