Why do we need a bunch of duplicate changes in jdk7u/hotspot ?

[David Holmes]

Hi Volker,

On 27/04/2012 6:59 PM, Volker Simonis wrote:
> could anybody please explain why it was necessary to reintegrate a
> whole lot of changes into hs23 of jdk7u/hotspot which have been in the
> hotspot repository since hs22 anyway?

This was discussed last year (with thanks to John Rose for these 
references):

http://mail.openjdk.java.net/pipermail/jdk7u-dev/2011-August/000161.html
http://mail.openjdk.java.net/pipermail/jdk7u-dev/2011-October/000582.html
http://mail.openjdk.java.net/pipermail/jdk7u-dev/2011-November/000748.html

Basically what you are seeing are fixes that went into hs22 and hs23 
after hs23 forked. hs22 went into 7u2 which became the basis for 7u3 
then 7u4. Then hs23 had to be integrated into 7u4 and so you end up with 
different changesets that duplicate the same actual changes.

David
-----

> This all happened with the following bulk integrations:
>
> http://mail.openjdk.java.net/pipermail/jdk7u-dev/2012-April/002588.html
> http://mail.openjdk.java.net/pipermail/jdk7u-dev/2012-April/002651.html
>
> and it affects (among others):
>
> 7059019: G1: add G1 support to the SA
> 7092412: G1: Some roots not marked during an initial mark that gets an
> evacuation failure
> 7045232: G1: pool names are inconsistent with other collectors (don't
> have 'Space')
> 7068215: G1: Print reference processing time during remark
> 7091032: G1: assert failure when NewRatio is used
> 7092245: G1: Wrong format specifier in G1PrintRegionLivenessInfo header output
> 7092238: G1: Uninitialized field gc_efficiency in
> G1PrintRegionLivenessInfo output
> 6484982: G1: process references during evacuation pauses
> 7075646: G1: fix inconsistencies in the monitoring data
> 7086533: G1: assert(!_g1->is_obj_dead(obj)): We should not be
> preserving dead objs: g1CollectedHeap.cpp:3835
> 7097053: G1: assert(da ? referent->is_oop() :
> referent->is_oop_or_null()) failed: referenceProcessor.cpp:1054
> 7097048: G1: extend the G1 SA changes to print per-heap space information
> 7092236: java/util/EnumSet/EnumSetBash.java fails
> 7092278: "jmap -finalizerinfo" throws
> "sun.jvm.hotspot.utilities.AssertionFailure: invalid cp index 0 137"
> 7096366: PPC: corruption of floating-point values with DeoptimizeALot
> 7100165: JSR 292: leftover printing code in methodHandleWalk.cpp
>
> Looking for each of this changes will show you that they are present
> two times in the repository with exactly the same changesets. E.g.:
> http://hg.openjdk.java.net/jdk7u/jdk7u4/hotspot/log?rev=7059019
>
> Regards,
> Volker