On 17/01/2015 12:24 PM, Daniel D. Daugherty wrote:
>
http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8068162-JVMTI-old.4/
src/share/vm/memory/universe.hpp
No comments.
src/share/vm/memory/universe.cpp
No comments.
src/share/vm/prims/jvmtiRedefineClasses.cpp
So redefining the Unsafe class is now very expensive because
we have to visit the i-table and v-table of every class (and
maybe interface?)...
Sorry I didn't follow this through all the rounds, but the bug report
states (and the code I looked at seems to be consistent with it) that
the throw_IllegalAccessError call is only added to itables - so why are
we also walking vtables?
David H.
-----
Based on the bug report 'Unsafe::throw_illegal_access' is some
magical method that can appear in any i-table or v-table entry.
Maybe only as part of some default methods thing? That's not
clear to me so I'm just guessing...
Is there some way to limit this visit to classes where the
magical method can appear? Or can it really appear anywhere?
Dan
On 1/16/15 12:14 PM, [email protected] wrote:
Dan, David H. or David C.,
May I ask one of you to look at the webrev below?
The issue itself is a little bit tricky, so it is not easy to review
despite the small size.
Coleen,
Does the webrev matches what we discussed with you?
Do you give me a thumbs up?
Thanks,
Serguei
May I ask
On 1/13/15 9:47 PM, [email protected] wrote:
Please, review the fix for:
https://bugs.openjdk.java.net/browse/JDK-8068162
Open webrevs:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8068162-JVMTI-old.4/
http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/jdk/8068162-Test-IsModifiableAgent/
Summary:
The sun.misc.Unsafe:throwIllegalAccessError() method is used in
place of a default
interface method in the itable if a default method was not defined
in the interface.
In fact, it happens for two interfaces that purhaps are
auto-generated:
java/nio/CharBuffer
java/nio/HeapCharBuffer
This approach creates a problem when the class sun.misc.Unsafe is
retransformed.
The Method* pointer to the old (redefined) method in the itable
triggers an assert
(see the hs_err log in the bug report).
Coleen told me that a similar approach is going to be implemented
for some vtable entries.
Coleen, thanks for suggesting a better fix for this issue!
The fix is to replace the old Unsafe method in the itable/vtable
with the latest method version.
Testing:
In progress: nsk.jdi.testlist, JTREG java/lang/instrument tests
Thanks,
Serguei
