RFR: JDK-8188312 Use CDS if present when running the Boot JDK during build
claes.redestad at oracle.com
Thu Oct 5 10:35:19 UTC 2017
On 2017-10-05 11:35, Magnus Ihse Bursie wrote:
>> Using -Xshare:auto should mean any case where a CDS archive can't be
>> used (for whatever reason) should be silently ignored. I'd be more
>> worried if -Xshare:on didn't fail in this case!
> But we're actively disabling verification of the CDS archive! How is
> then CDS supposed to know that it contains code for core classes that
> has been superseded using -Xbootclasspath/p?
>>> This was supposed to be a quick and simple patch to get a small, but
>>> useful improvement. It's not worth a lot of investigation or fixes,
>> Repeating my suggestion I put as a comment in the RFE: add
>> -Xshare:auto but leave out the code to dump an archive in the build
>> (for now),
>> so that those of us who prepare our boot JDK to have CDS archive
>> generated can get the benefit from it.
> Well then, can you then guarantee that this will not break when
> replacing stuff using -Xbootclasspath/p? Because I don't want to be
> debugging things when a slightly different version of the class was
> *not* used as it should since an old cached version in CDS was picked
> up instead. :-(
I was not suggesting adding -XX:-VerifySharedSpaces - Ioi can probably
tell if disabling this verification could lead to a corrupt heap state
in presence of -Xbootclasspath/p.
I think -Xshare:auto alone is safe no matter what.
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