This interface abstracts over access to operating system-level threads in the underlying process. It is designed to be minimal and generic to allow cross-platform compatibility.

The basic operation this interface supports is creating a sun.jvm.hotspot.debugger.ThreadProxy "token" for an existing thread. As an example, the HotSpot VM contains a list of Java threads, encapsulated in VM-specific JavaThread objects. Each of these contains a platform-dependent field with the OS-level thread identifier; on Solaris, this field's type is "thread_t", while on Windows, it is HANDLE. It is necessary to be able to map from these fields to a ThreadProxy object, in particular to be able to get the thread's context. However, since the types of these fields vary greatly from OS to OS (some use integers as thread IDs, some use pointers as thread handles) it is not possible to define one particular type (Address, long) in this interface as the lookup "key" for a Thread.

For this reason this mapping mechanism takes the Address of the memory location containing the thread identifier. On Solaris, this is the address of a location containing a thread_t; on Windows, this is the address of a location containing a HANDLE for a thread. On Linux, this is the address of a location containing a pthread_t.

The sun.jvm.hotspot.debugger.cdbg.CDebugger interface provides access to the entire thread list of the target process, but this is optional functionality not required to get the SA to work.