On 6/3/20 12:34 PM, Calvin Cheung wrote:
I saw David has commented on this. So I'll leave the assert as before
and I've added another assert (see line 1691):
1687 // The following ensures that the caller's nest host is the
same as the lambda proxy's
1688 // nest host recorded at dump time.
1689 assert(nest_host->has_nest_member(caller_ik, THREAD) ||
1690 nest_host == caller_ik, "caller_ik failed nest member
check");
I don't think this assert is needed. caller_ik can be a hidden class
and so this assert is not correct then.
Is there any issue to archive lambda proxy class whose caller is a
hidden class? Is there any assumption in the CDS implementation that
the caller class is always a normal class?
1691 assert(nest_host == shared_nest_host, "mismatched nest host");
This is good.
In SystemDictionary::load_shared_lambda_proxy_class, it checks the flag:
1422 if (initialize) {
1423 loaded_ik->initialize(CHECK_NULL);
1424 }
I think JVM_LookupLambdaProxyClassFromArchive is a more appropriate
place to link and initialize the class before return. I expect
load_shared_lambda_proxy_class does loading only and linking and
initialization should be separate from loading.
On a related note, in the existing jvm_lookup_define_class in jvm.cpp:
if (init) {
ik->initialize(CHECK_NULL);
} else {
ik->link_class(CHECK_NULL);
}
I don't think the else is necessary as the ik->link_class(CHECK_NULL)
has been done within the SystemDictionary::parse_stream.
Harold and Lois can chime in here. I think ik->link_class may be for
unsafe anonymous class to prepare for constant pool patching.
Currently, the strong vs weak hidden class isn't recorded in the archive.
:
-----
For now, I've added an assert in
JVM_RegisterLambdaProxyClassForArchiving to make sure the hidden class
is strong so that when things changed later, we'll notice it.
An assert is good.
3752 if (invokedName == NULL || invokedType == NULL || methodType ==
NULL ||
3753 implMethodMember == NULL || instantiatedMethodType == NULL) {
3754 return NULL;
3755 }
Should this throw NPE instead?
This adds a VM call for every lambda proxy class creation. Do you
have any the performance measurement when CDS is not on? Any
performance regression?
Here's the perf data with CDS disabled. The data is for loading 200
lambda proxy classes.
Actually the Java side checks if CDS is enabled before it calls the VM.
So it's good.
Mandy
