Request for review (S): add the JRE name to the error log

[Christian Thalinger]

On Jun 13, 2012, at 4:06 PM, Christian Thalinger wrote:

> 
> On Jun 13, 2012, at 2:37 PM, Coleen Phillimore wrote:
> 
>> 
>> Kris,
>> 
>> I'm sorry I didn't comment on this earlier.  This looks fantastic.  I tried to do this but didn't know how and had settled on the not-very-good version line in vmError that you improved.   Thanks!!
> 
> Coleen, will you sponsor this change or should I do it?

I filed:

7176856: add the JRE name to the error log

and will push it tomorrow to hotspot-comp.

-- Chris

> 
> -- Chris
> 
>> Coleen
>> 
>> On 6/13/2012 5:12 PM, Christian Thalinger wrote:
>>> 
>>> Does anyone from runtime have an opinion on this one?
>>> 
>>> -- Chris
>>> 
>>> On May 16, 2012, at 1:26 PM, Christian Thalinger wrote:
>>> 
>>>> 
>>>> On May 16, 2012, at 12:44 PM, Krystal Mok wrote:
>>>> 
>>>>> Hi all,
>>>>> 
>>>>> Could I get some review for this change, please?
>>>>> https://gist.github.com/2709918#file_jre_name.patch
>>>>> I'm considering this as an initial draft version, and will improve it later on
>>>>> based on comments received.
>>>>> 
>>>>> Background:
>>>>> 
>>>>> An earlier case on hotspot-dev [1][2] seemed to have hit a bug caused by mix-
>>>>> matching an Oracle JRE with a OpenJDK-based HotSpot VM.
>>>>> 
>>>>> Chris suggested [3] that, to better aid future analysis of similar problems,
>>>>> it's useful to print the JRE name in the error log, in addition to the JRE
>>>>> version as printed currently. This patch implements Chris' suggestion.
>>>>> 
>>>>> An example of the effect of this patch is avaiable [4].
>>>>> 
>>>>> There are a few details that I'm not too sure about yet, and I'm looking for
>>>>> comments on them:
>>>>> 
>>>>> 1. How and when should I get the JRE name?
>>>>> 
>>>>> The JRE name is only exposed as a field of a Java-level class, namely the
>>>>> "java_runtime_name" constant field in sun.misc.Version. I couldn't find it
>>>>> exposed anywhere else. It is set into the Java-level system properties, by the
>>>>> key "java.runtime.name", but that's not immediately available to the VM side.
>>>>> 
>>>>> In my patch, I'm fetching the JRE name from sun.misc.Version.java_runtime_name
>>>>> immediately after java.lang.System.initializeSystemClass() is invoked, and then
>>>>> storing it in a static field in JDK_Version. This is safer to do then fetching
>>>>> the name during error reporting, because it may be unreliable to access Java
>>>>> heap contents when the VM is crashing.
>>>>> 
>>>>> There are other alternatives that I've thought about. One is adding a new
>>>>> private interface between JDK/JVM that would allow the JDK to expose its name
>>>>> to the VM directly, perhaps with a new function JDK_GetName0(). But this is
>>>>> more involved then the proposed change.
>>>>> 
>>>>> 2. Where should I store the JRE name?
>>>>> 
>>>>> As mentioned, I'm storing it in a newly added static field in JDK_Version right
>>>>> now. But I'm not sure if this is the place it belongs. Universe doesn't seem
>>>>> like the right place, neither.
>>>>> 
>>>>> Any suggestions or comments are welcomed.
>>>> 
>>>> I looked at the changes and I think this is the right way to implement it.  It will definitely help debugging some strange crashes like the one mentioned.
>>>> 
>>>> -- Chris
>>>> 
>>>>> 
>>>>> Should I cc serviceability-dev as well?
>>>>> 
>>>>> Regards,
>>>>> Kris
>>>>> 
>>>>> [1]: http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2012-May/007647.html
>>>>> [2]: http://mail.openjdk.java.net/pipermail/hotspot-dev/2012-May/005711.html
>>>>> [3]: http://mail.openjdk.java.net/pipermail/hotspot-dev/2012-May/005725.html
>>>>> [4]: https://gist.github.com/2709918
>>>> 
>>> 
> 

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