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

Vladimir Kozlov vladimir.kozlov at
Tue Dec 18 12:01:34 PST 2012

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.


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
> <>
> Bug link at
> The changes were tested with JCK, JPRT, JTREG, and UTE tests, and with
> hand-run tests using different ObjectAlignmentInBytes values.
> Thanks, Harold

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