how to bring jvm to safepoint

[David Holmes]

Tony,

I don't see anything obviously wrong with what you attempted. Can you 
show the full stack dump from the error.

David Holmes

Tony Guan said the following on 07/30/10 07:29:
> Dear all,
> 
> I want to invoke the GC at a certain time, for example, when a certain
> method is called at runtime, so I created a new subtype of
> VM_GC_Operation class, and initialized it with an object op, finally,
> executed using:VMThread::execute(&op)
> 
> then I got the following error message:
> 
> #  Internal Error
> (/home/tony/software/OpenJDK/jdk7/hotspot/src/share/vm/runtime/thread.cpp:777),
> pid=29652, tid=1096460624
> #  Error: Possible safepoint reached by thread that does not allow it
> 
> The reason for the fail is that
> Thread::check_for_valid_safepoint_state() didn't pass because the
> currentThread is not a VMThread.
> 
> My question is: how do I bring the current thread to a safepoint? or
> how do I call a GC operation properly? is there any prerequisite for
> doing so?
> 
> Thanks!
> 
> Tony (Xiaohua Guan)