On 9/18/17 6:14 AM, Robbin Ehn wrote:
Hi,
FYI: It's been long since duke:
0: nonstatic_field(nmethod, _stack_traversal_mark,
long) \
It's now also volatile.
The correct type should/could probably be some like
(u)int_fast32_t/intx or whatever.
If there is an issue with variable length types in vmStructs we have
had that issue for very long AFAICT.
Hi Robbin,
I was more concerned with it being variable in general between 32-bit
and 64-bit platforms, not that it was an issue for vmStructs. This does
not seem like the type of value that would need to be a different size
depending on the bitness, so it should be made whichever smallest size
that is big enough. As you point out, something like intx, although the
data structure it is in is full of ints, so probably int would be
sufficient.
thanks,
Chris
But looking at error message below:
field "_stack_traversal_mark" in type nmethod is not of type jlong,
but instead of type long
It was jlong for about a month until I reverted that change (back to
long but volatile).
So it looks like you are running tools from an older build with a
newer vm or something like that ?
/Robbin
On 09/17/2017 10:13 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
[2] 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.hotspot.types.basic.BasicType.getField(BasicType.java:206)
at
jdk.hotspot.agent/sun.jvm.hotspot.types.basic.BasicType.getField(BasicType.java:212)
at
jdk.hotspot.agent/sun.jvm.hotspot.types.basic.BasicType.getJLongField(BasicType.java:249)
at
jdk.hotspot.agent/sun.jvm.hotspot.code.NMethod.initialize(NMethod.java:108)
at
jdk.hotspot.agent/sun.jvm.hotspot.code.NMethod.access$000(NMethod.java:35)
at
jdk.hotspot.agent/sun.jvm.hotspot.code.NMethod$1.update(NMethod.java:81)
at
jdk.hotspot.agent/sun.jvm.hotspot.runtime.VM.registerVMInitializedObserver(VM.java:451)
at
jdk.hotspot.agent/sun.jvm.hotspot.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/~ysuenaga/JDK-8187597/webrev.00/
I cannot access JPRT. So I need reviewer.
Thanks,
Yasumasa
