Providing users with thread type

[David Holmes]

Hi Jc,

On 19/04/2019 12:18 am, Jean Christophe Beyler wrote:
> Hi all,
> 
> When doing profiling, often users have a hard time determining what is 
> happening inside libjvm.so. When doing profiling, the JVM seems like a 
> black box and it is hard to differentiate between a thread doing 
> GC/Compile/Actual VM work since all they get is profiles from libjvm.so 
> but not what are the various profiles doing.
> 
> We have a small patch that provides a method to users to ask what is the 
> type of the current thread, which then provides one of those types 
> (GC/Compile/Actual VM work).
> 
> I'd like to ask if this seems like a reasonable thing to do and should I 
> work on providing this via a JVMTI call. Something like 
> GetCurrentThreadType.

I think it would be difficult to put something like this in JVM TI given 
that the use of threads within the JVM are purely an implementation 
detail and not standardized in any way. And many of those threads are 
hidden from JVM TI anyway.

The names of threads are the normal way to see what "type" of thread 
you're dealing with.

Cheers,
David

> 
> What do you all think? Is this sane and possible to try to push forward?
> 
> Thanks for your opinions,
> Jc