On 04/02/2013 01:02 PM, serguei.spit...@oracle.com wrote:
On 4/1/13 3:51 PM, Coleen Phillimore wrote:
On 04/01/2013 06:02 PM, serguei.spit...@oracle.com wrote:
On 4/1/13 1:09 PM, Coleen Phillimore wrote:
Hi Serguei,
Sorry for the delay in reviewing this.
In instanceKlass.cpp line 2730, can you make that mtClass since
it's part of class metadata?
Fixed.
Thank you for the catch!
In methodHandles.cpp, I think the whole member name table mechanism
could be protected by #if INCLUDE_JVMTI since it's not needed
unless you have jvmti built in the vm. And you don't need to call
add_method_handle() or just have it do JVMTI_RETURN or something
for the minimal vm.
My understanding was that John is considering to use the
MemberNameTable in the future for the compilation purposes.
However, I can temporarily place it under #if INCLUDE_JVMTI
until the compiler team decides what to do with it.
Also, I think you should consider a global table rather than one
per class. I think we discussed this and may have decided that
speed of adding these is important, but depending on how many are
actually used per class, there's one pointer per class.
I thought we've reached a consensus and decided to add MNT pointer
per class as it is performance sensitive for indy calls.
Anyway, before changing it to a hashtable I'd want to hear from John
and Christian first.
Definitely would like to hear from John and Christian. We did
discuss it but I wasn't totally convinced this field is more
important than the others that were going to be moved out of Klass*
to make it smaller. Some statistics for some sample applications
like eclipse would be great.
I'm not sure what statistics do you mean here.
Do you mean a footprint or performance statistics?
As I understand from our previous discussion there can be a more
general solution for the footprint issue.
As such we could attack the footprint problem separately.
Yes, there are more general solutions to the footprint issue. One
would be moving these JVMTI fields and initializing them lazily and
there are other footprint improvements. One additional improvement
would be to remove this field which will be mostly zero and put this in
a hashtable and not allocate it per class.
For instance, we could separate all JVMTI fields from InstanceKlass
and initialize them lazily.
But I'd not want to go deep into this discussion.
You do not want me to get involved into the footprint work, do you? :)
Also, the decision how to represent the MNT depends on its future
usage by the compiler team.
As we agreed, the compiler team is going to adjust the MNT to their needs
at some point when it is more convenient for them.
So that, could we make a final decision when the whole picture is ready?
It would be better to approach it in some steps.
Currently, this bug blocks other work on the JVMTI support of jsr-292.
I don't know what the jsr 292 team has in store for this field but it's
still a footprint cost that's for only a special case. So this is okay
if you file a bug so that we can remove it and reimplement this table to
be global or a hashtable.
Coleen
Thanks,
Serguei
Coleen
Maybe they could be organized as a hashtable instead like the
method handle intrinsics?
The code itself looks good everywhere, except for the concern about
footprint.
I very appreciate you found a time to review it!
There are not many people having an expertize in this area.
Thanks,
Serguei
Thanks,
Coleen
Can you make this mtClass on line
On 03/26/2013 04:37 AM, serguei.spit...@oracle.com wrote:
Please, review the following fix.
The fix was preliminarily reviewed by Coleen, Christian
and John but still a final and open jdk review is needed.
So that, everyone is welcome to review the fix!
This is open webrev:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2013/hotspot/8008511-JVMTI-JSR292.1/
The CR is:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8008511
https://jbs.oracle.com/bugs/browse/JDK-8008511
The problem is that the old version of the bootstrap method is
re-invoked
after a popframe from the bootstrap method execution.
It is because the MemberName keeps a stale reference to the old
method version.
The solution (suggested by John Rose) is to lazily create and keep
up-to-date a MemberNameTable
which plays a role of MemberName cache assosiated with the
InstanceKlass.
Then, at the Class redefinition, this cache is used to replace the
old method
references in the MemberName's with the new method references.
The MemberNameTable is based on the GrowableArray<jweek>.
A C_HEAP array is allocated at the first call to
InstanceKlass::add_member_name().
It is released in the InstanceKlass::release_C_heap_structures().
A global week reference to member name oop is stored in the
MemberNameTable.
It allowed to avoid having the oops_do() in the MemberNameTable.
Also, the MemberNameTable won't hold member name oops in memory.
The MemberNameTable_lock mutex is added to serialize
MemberNameTable's updates.
The following No_Safepoint_Verifier has been disabled:
* src/share/vm/prims/methodHandles.cpp*:
799 int MethodHandles::find_MemberNames(Klass* k,
. . .
803 DEBUG_ONLY(No_Safepoint_Verifier nsv);
It is probably Ok, but, please, let me know if it is not.
The assert related to locking is fired if it is not disabled.
Test coverage: vm.mlvm, nsk.jvmti, nsk.jdi tests on multiple
platforms (32 vs 64-bit too).
The testing looks good so far.
Thanks,
Serguei
