[crac] RFR: 8365241: [CRaC] Ignore new arguments when CRaCIgnoreRestoreIfUnavailable is true

[Timofei Pushkin]

On Mon, 11 Aug 2025 14:39:01 GMT, Radim Vansa <rvansa at openjdk.org> wrote:

>> Arguments are not passed to the restored process when `-XX:+CRaCIgnoreRestoreIfUnavailable` is set on restore. The check is performed on the side of the restoring VM since in the restored VM `CRaCIgnoreRestoreIfUnavailable` could have been set before the current restore.
>> 
>> Documentation for the new arguments feature and `CRaCIgnoreRestoreIfUnavailable` is also added, explaining this behavior.
>
> src/java.base/share/man/java.md line 1099:
> 
>> 1097:     instead of failing.
>> 1098: 
>> 1099:     When restoring with this option, you should specify a main class and its
> 
>> you **should** specify a main class
> 
> I guess we shall make this mandatory -> you **must** sepecify a main class? Do we have a test for the case when you run plain `java -XX:CRaCRestoreFrom=... -XX:+CRaCIgnoreRestoreIfUnavailable` and the image is not present?

No, there is no such test currently.

You do not always have to specify a main class since if the image exists the main won't be used. Initially I wrote "you are expected to specify" and made it shorter into this version.

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PR Review Comment: https://git.openjdk.org/crac/pull/261#discussion_r2267037373