RFR JDK-8198253: ThreadInfo.from(CompositeData) assigning fields incorrectly in JDK 9

[mandy chung]

Hi Jeremy,

lockedMonitors and lockedSynchronizers attribute are not optional if that's
the issue you try to resolve. I think the specification should be clarified.

ThreadInfo::from supports the three different versions for interoperability:
1. CompositeData for JDK 1.5 ThreadInfo with no lockedMonitors and
    lockedSynchronizers attribute
2. CompositeData for JDK 6 ThreadInfo with lockedMonitors and lockedSynchronizers
    attributes
3. CompositeData for JDK 9 ThreadInfo with lockedMonitors and lockedSynchronizers
    attributes and with daemon and priority attribute.

JMX client can connect to a running VM in any version and get back a
proper ThreadInfo.

If ThreadInfo::from is called with a CompositeData containing daemon and
priority attribute but lockedMonitors and lockedSynchronizers attributes are
absent then the given CompositeData is invalid and IllegalArgumentException
should be thrown.

Does this help?

Mandy


On 2/15/18 4:46 PM, Jeremy Manson wrote:
> Hi folks,
>
> Been a long time!  I'd like someone to do a code review. This is in 
> code I wrote a few years ago, and got wrong.  At the time, David 
> Holmes, Staffan Larsen, and Mandy Chung reviewed it.  It does mean 
> that people using ThreadInfo.from(CompositeData) may be getting the 
> wrong values out for ThreadInfo, so it is definitely worth fixing.
>
> The patch below fixes the bug, but is a pretty questionable approach.  
> Better approaches happily considered.
>
> Patch:
> http://cr.openjdk.java.net/~jmanson/8198253/webrev.00/ 
> <http://cr.openjdk.java.net/%7Ejmanson/8198253/webrev.00/>
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8198253
>
> Thanks!
>
> Jeremy

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