hg: jdk8/tl/jdk: 7194897: JSR 292: Cannot create more than 16 instances of an anonymous class; ...

Remi Forax forax at univ-mlv.fr
Wed Nov 6 10:37:14 UTC 2013

On 11/05/2013 11:11 AM, Joel Borggrén-Franck wrote:
> On 5 nov 2013, at 10:51, Peter Levart <peter.levart at gmail.com> wrote:
>> On 11/05/2013 10:33 AM, Joel Borggrén-Franck wrote:
>>>>> I would also restructure the Method/Constructor accessor logic differently. The check for ReflectUtil.isVMAnonymousClass() can be performed just once (in the newMethodAccessor/newConstructorAccessor methods) and based on this check, create accessor:
>>>>> - for classic declaring class - as is / unchanged
>>>>> - for anonymous declaring class - just create and return NativeMethodAccessorImpl without a parent
>>>>> Then in NativeMethodAccessorImpl (and same for constructor), modify the inflation checking logic:
>>>>>          if (parent != null && ++numInvocations > ReflectionFactory.inflationThreshold()) {
>>>>>              MethodAccessorImpl acc = (MethodAccessorImpl)
>>>>>                  new MethodAccessorGenerator().
>>>>>                      generateMethod(method.getDeclaringClass(),
>>>>>                                     method.getName(),
>>>>>                                     method.getParameterTypes(),
>>>>>                                     method.getReturnType(),
>>>>>                                     method.getExceptionTypes(),
>>>>>                                     method.getModifiers());
>>>>>              parent.setDelegate(acc);
>>>>>          }
>>> I don't like adding even more special cases to this check. IMHO a better way that we discussed and rejected, opting for a smaller change, is to create a NonInflatingMethodAccessor and just drop in one of those without a delegate for when creating the accessor for methods/ctors on anonymous classes.
>> Even better. I would name the new class NativeMethodAccessorImpl and the one doing inflation InflatingNativeMethodAccessorImpl which would extend NativeMethodAccessorImpl, override invoke() and call super.invoke()... This way, no native methods duplication is needed. invoke() is already an interface method with 2 implementations. Now it will have 3. Does this present any difference for dispatch optimization?
> FWIW i think the magic number is 4, but I don't know where I got that. Anyhow, this might be slightly controversial, but for all code I care about (reflective invocation of methods/ctors on non-VM-anonymous classes) the check happens exactly once as is.

No, the magic number is 2 (by default),
you can look for TypeProfileWidth in the vm code.


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