RFR (XS): 8022595: JSR292: deadlock during class loading of MethodHandles, MethodHandleImpl & MethodHandleNatives

Vladimir Ivanov vladimir.x.ivanov at oracle.com
Tue Aug 20 10:05:45 PDT 2013

201 lines changed: 201 ins; 0 del; 0 mod;

Some classes in j.l.invoke have circular dependencies between them which 
leads to deadlocks during class initialization when multiple threads 
exercise JSR292 functionality.

JSR292 core classes are among "well-known" classes to VM and they are 
preloaded during VM startup (see 
SystemDictionary::initialize_preloaded_classes). However, it doesn't 
force preloaded classes to be initialized (doesn't execute static 
initializers). Thus, these classes should be explicitly pre-initialized 
in order to avoid deadlocks.

Based on my observations of possible deadlock scenarios, I chose 3 
classes to pre-initialize:
	- MethodHandle
	- MemberName
	- MethodHandleNatives

I placed the code right after compilers initialization because during 
method resolution for signature polymorphic intrinsics, compilation 
tasks are issued (see SystemDictionary::find_method_handle_intrinsic for 
details) and they are missed if compiler subsystem isn't ready yet.

Testing: failing test, regression test, JPRT, jdk/test/j/l/invoke, 
vm.mlvm.testlist, octane.


Best regards,
Vladimir Ivanov

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