Java.lang.Thread.eetop

Question

who knows what this field in Thread class for?

Answer 1

Whoops, spoke too soon...
In 1.4 it is used in the vm\memory\javaClass.cpp file.
The following comment explains it but doesn't seem to make it very clear in my mind.
// Note: JDK1.1 and before had a privateInfo_offset field which was used for the
//       platform thread structure, and a eetop offset which was used for thread
//       local storage (and unused by the HotSpot VM). In JDK1.2 the two structures
//       merged, so in the HotSpot VM we just use the eetop field for the thread
//       instead of the privateInfo_offset.
.Guessing I would say that the real memory foot print for a Java Thread instance has the implementation specific thread data at a specific point. And that is the offset to that specific point.
For more information you would need to chase down the "JavaThread" item that is referred to in java_lang_Thread::thread(oop java_thread).