Request for review 8005075: CDS archive with one alignment causes crash when run with different alignment

[Vladimir Kozlov]

Recording ObjectAlignmentInBytes in CDS is good. Thank you for doing it.
My question is why bigger original alignment is fine? I thought CDS 
works only when it is exactly the same.

Thanks,
Vladimir

On 12/17/12 7:23 AM, harold seigel wrote:
> Please review the following change to fix bug 8005075.
>
> Summary:  This change prevents a crash when a CDS archive is created
> with a value for -XX:+ObjectAlignmentInBytes that is smaller than the
> ObjectAlignmentInBytes value used when running with -Xshare:on. This fix
> stores the ObjectAlignmentInBytes in the CDS archive so that when the
> archive is read, hotspot can compare the archive's alignment with the
> current alignment and issue the following diagnostic if the archive's
> alignment is too small:
>
>     An error has occurred while processing the shared archive file.
>     The shared archive file was created with a smaller Object Alignment
>     value.
>
> This webrev also cleans up some text in globals.hpp and fixes a small
> problem with -XX:SharedReadOnlySize.  The existing code was always
> setting SharedReadOnlySize to 14M regardless of what was requested.
> This prevented users from being able to expand the CDS archive's
> SharedReadOnly section.
>
> Open webrev at http://cr.openjdk.java.net/~hseigel/bug_8005076/
> <http://cr.openjdk.java.net/%7Ehseigel/bug_8005076/>
>
> Bug link at http://bugs.sun.com/view_bug.do?bug_id=8005076
>
> The changes were tested with JCK, JPRT, JTREG, and UTE tests, and with
> hand-run tests using different ObjectAlignmentInBytes values.
>
> Thanks, Harold