Hi Coleen, in VM_RedefineClasses::doit:
This updates the breakpoints:
MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true,
/*redefinition_walk*/true);
And this removes breakpoints:
for (int i = 0; i < _class_count; i++) {
redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
}
So we skip updating, since we do remove them after we updated them.
But you are the expert here. Let me know if there is something I missed.
OopHandle just adds more code.
Thanks for having a look, Robbin
On 12/16/19 1:32 PM, [email protected] wrote:
I have to think about this. Could there be breakpoints in old emcp methods
that we do not remove? The metadata_do function is trying to keep old Methods
from being deleted while there are still references to them.
http://cr.openjdk.java.net/~rehn/8235912/v1/webrev/src/hotspot/share/prims/jvmtiImpl.hpp.udiff.html
+ oop* _class_holder; // keeps _method memory from being deallocated
We created the class OopHandle to encapsulate strong oopStorage references,
although it's missing oop_store. Can you use that?
Coleen
On 12/16/19 4:47 AM, Robbin Ehn wrote:
Hi all, please review.
From issue, https://bugs.openjdk.java.net/browse/JDK-8235912:
JvmtiBreakpoints are walked via VMThread oops_do (the breakpoint is in a vm
operation) before they are installed in the safeopint and after they have been
installed, walked with JvmtiCurrentBreakpoints::oops_do().
By putting the class holder inside oopStorage there is no need for this.
JvmtiCurrentBreakpoints::metadata_do is not needed because redefine classes
actually removes the breakpoints before updating them (so there is no
breakpoints to update).
We can just remove metadata_do.
I also removed some unused code.
Changeset:
http://cr.openjdk.java.net/~rehn/8235912/v1/webrev/
Passes several runs of nsk jvmti/jdi and t1-7.
Thanks, Robbin
