Request for review (S): add the JRE name to the error log
coleen.phillimore at oracle.com
Wed Jun 13 14:37:14 PDT 2012
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!!
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?
>>> I'm considering this as an initial draft version, and will improve
>>> it later on
>>> based on comments received.
>>> An earlier case on hotspot-dev  seemed to have hit a bug
>>> caused by mix-
>>> matching an Oracle JRE with a OpenJDK-based HotSpot VM.
>>> Chris suggested  that, to better aid future analysis of similar
>>> 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 .
>>> 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 <http://java.runtime.name/>", but that's not
>>> immediately available to the VM side.
>>> In my patch, I'm fetching the JRE name from
>>> 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?
>>> : https://gist.github.com/2709918
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