RFR: JDK-8187597: WrongTypeException is occurred at CLHSDB jstack after JDK-8186837
Yasumasa Suenaga
yasuenag at gmail.com
Tue Sep 19 03:19:40 UTC 2017
Thanks David,
BTW, can I push this change after jdk10/master is opened?
I cannot access JPRT.
Yasumasa
2017/09/19 午後0:08 "David Holmes" <david.holmes at oracle.com>:
> Hi Yasumasa,
>
> On 19/09/2017 12:55 PM, Yasumasa Suenaga wrote:
>
>> Thanks Chris, Robbin,
>>
>> I'm waiting reviewer(s) for this change.
>>
>
> Reviewed.
>
> This simply reverts the change of 8185102.
>
> Thanks,
> David
> -----
>
>
>> Yasumasa
>>
>>
>> 2017/09/19 午前7:14 "Chris Plummer" <chris.plummer at oracle.com <mailto:
>> chris.plummer at oracle.com>>:
>>
>> Hi Yasumasa,
>>
>> Ok, I see now that CIntegerField is just an interface, so it's up to
>> a class to implement getValue() to fetch the field. I'm a bit
>> unclear on how that part works, but from responses by others, it
>> seems this is ok.
>>
>> I've run all the tests I can find that use jstack or jhsdb, and the
>> assert was not triggered. Probably need to have a NMethod on the
>> stack to trigger the code you are fixing.
>>
>> thanks,
>>
>> Chris
>>
>>
>> On 9/17/17 1:13 AM, Yasumasa Suenaga wrote:
>>
>> Hi Chris,
>>
>> I've tested this issue on Fedora 26 x86_64.
>> I think we can sue CIntegerField at this point because
>> CIntegerField is not specialized for various int size [1].
>> In fact, CIntegerField had been used at this point [2], and HSDB
>> worked fine.
>>
>>
>> Thanks,
>>
>> Yasumasa
>>
>>
>> [1]
>> http://hg.openjdk.java.net/jdk10/master/file/fd36993f7bf5/
>> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/types/
>> CIntegerField.java#l29
>> <http://hg.openjdk.java.net/jdk10/master/file/fd36993f7bf5/
>> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/types/
>> CIntegerField.java#l29>
>> [2] http://hg.openjdk.java.net/jdk10/master/rev/cbfdbefc6ea3
>> <http://hg.openjdk.java.net/jdk10/master/rev/cbfdbefc6ea3>
>>
>>
>> On 2017/09/17 3:58, Chris Plummer wrote:
>>
>> Hi Yasumasa,
>>
>> Is this on a 32-bit system? I don't see how you could
>> otherwise call getCIntegerField() on a long type. jlong is
>> always 64-bit and long is (generally) 32-bit on 32-bit
>> systems, and 64-bit on 64-bit systems, at least that seems
>> to be the case with linux.
>>
>> From what I can see, _stack_traversal_mark is now the only
>> long type in vmStructs.cpp. I don't know that we have a
>> mechanism to safely fetch it on both 32-bit and 64-bit
>> systems.
>>
>> _stack_traversal_mark seems to be a long because _traversals
>> is also a long.
>>
>> static long _traversals; //
>> Stack scan count, also sweep ID.
>>
>> This too might be considered a bug. I'm not sure why you
>> would want the size of this field to vary between 32-bit and
>> 64-bit systems (adding compiler-dev to help answer that).
>>
>> So, while I would agree that your fix is generally in the
>> right direction, I think we first need to revisit the use of
>> long for these fields. If they can be changed to an int,
>> then your fix is correct (pending the changes to int). If
>> not, then maybe we need getCLongField() support.
>>
>> And lastly, we really should have a test to detect this bug.
>> Maybe we already do, and it is failing but is going
>> unnoticed for some reason. I'll try to look into that some
>> more on Monday.
>>
>> thanks,
>>
>> Chris
>>
>> On 9/16/17 5:20 AM, Yasumasa Suenaga wrote:
>>
>> Hi all,
>>
>> I tried to get thread dump via jstack command on CLHSDB.
>> But it was failed as below:
>>
>> ```
>> Caused by: sun.jvm.hotspot.types.WrongTypeException:
>> field "_stack_traversal_mark" in type nmethod is not of
>> type jlong, but instead of type long
>> at
>> jdk.hotspot.agent/sun.jvm.hots
>> pot.types.basic.BasicType.getField(BasicType.java:206)
>> at
>> jdk.hotspot.agent/sun.jvm.hots
>> pot.types.basic.BasicType.getField(BasicType.java:212)
>> at
>> jdk.hotspot.agent/sun.jvm.hots
>> pot.types.basic.BasicType.getJLongField(BasicType.java:249)
>> at
>> jdk.hotspot.agent/sun.jvm.hots
>> pot.code.NMethod.initialize(NMethod.java:108)
>> at
>> jdk.hotspot.agent/sun.jvm.hots
>> pot.code.NMethod.access$000(NMethod.java:35)
>> at
>> jdk.hotspot.agent/sun.jvm.hots
>> pot.code.NMethod$1.update(NMethod.java:81)
>>
>> at
>> jdk.hotspot.agent/sun.jvm.hots
>> pot.runtime.VM.registerVMInitializedObserver(VM.java:451)
>> at
>> jdk.hotspot.agent/sun.jvm.hots
>> pot.code.NMethod.<clinit>(NMethod.java:79)
>> ... 23 more
>> ```
>>
>> I think this exception is caused by JDK-8186837.
>> This changeset has changed the type of
>> `nmethod::_stack_traversal_mark` to `long` from `jlong`.
>>
>> SA should follow this change.
>>
>> I uploaded a webrev for this issue. This webrev is
>> generated from consolidated repo (jdk10/master).
>> Could you review it?
>>
>> http://cr.openjdk.java.net/~ys
>> uenaga/JDK-8187597/webrev.00/
>> <http://cr.openjdk.java.net/~y
>> suenaga/JDK-8187597/webrev.00/>
>>
>>
>> I cannot access JPRT. So I need reviewer.
>>
>>
>> Thanks,
>>
>> Yasumasa
>>
>>
>>
>>
>>
>>
>>
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