Alexei Fedotov wrote:
Gregory, Ilya, TI gurus,
Could you please help me to understand why do we need a global list of
ia32 specific code chunks VM_Global_State::loader_env->dcList? Cannot
we use good old CodeChunkInfo structure?
The information contained in dcList is different from CodeChunks. It
contains generated stubs which are not compiled Java methods. It is
necessary for GenerateEvents [1] function implementation with
JVMTI_EVENT_DYNAMIC_CODE_GENERATED argument. An agent may request to
receive all missed DynamicCodeGenerated events which it could have
missed, and therefore it is necessary to store information about
generated stubs in VM.
I have noticed that access to the list is not thread safe (you put
TODO comment here). Does it mean we have some intermittent crashes due
to this issue?
Yes, this FIXME stands true. It is possible to get a race condition if
you run a profiling JVMTI agent which uses GenrateEvents function while
multithreaded application is executed.
But in the normal mode when JVMTI is not used this list is only written,
and never used. I think that compile_add_dynamic_generated_code_chunk
should have a check that ti->isEnabled(), or it is just wasting the memory.
[1]
http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#GenerateEvents
--
Gregory
