Could the JIT be started before JVMTI agents are loaded?

[Daniel D. Daugherty]

The compiler is initialized after JVMTI has posted the VM_INIT
event intentionally. The compiler may have to initialize differently
depending on the capabilities that were enabled by the JVMTI agent.

Dan


Volker Simonis wrote:
> Hi,
>
> we currently have some problems with long startup times due to JVMTI
> agents loaded with -javaagent. While investigating the problem we
> realized that the JIT compiler is only started AFTER the agent was
> loaded and initialized and therefore the whole agent initialization
> takes place in interpreted mode. Here is the corresponding code from
> thread.cpp:
>
>      3137   // Notify JVMTI agents that VM initialization is complete
> - nop if no agents.
>      3138   JvmtiExport::post_vm_initialized();
>      3139
>      3140   Chunk::start_chunk_pool_cleaner_task();
>      3141
>      3142   // initialize compiler(s)
>      3143   CompileBroker::compilation_init();
>
> Is there any particualr reason that the JIT gets initialized only
> after the agent initialization or could it be done just as well
> before? A short test where we placed
> "CompileBroker::compilation_init()" just before
> "JvmtiExport::post_vm_initialized()" succeeded with a considerable
> startup speedup, but we are not sure if this change would be valid in
> general.
>
> Regards,
> Volker
>