About debugging multi-threaded applications
The debugger tracks the current thread using the debugger variable,
$thread. You can use this variable in print commands or in expressions.
Threads are displayed in the Debug Control view with a unique ID that is used by the debugger and a unique ID from the Operating System (OS), for example:
os_idle_demon #3 stopped (USR) (ID 255)
#3 is the unique ID used by the debugger,
(USR) indicates the user mode, and
ID 255 is the ID from the OS.
A separate call stack is maintained for each thread and the selected stack frame is shown in bold text. All the views in the Development Studio perspective are associated with the selected stack frame and are updated when you select another frame.
Figure 10-1 Threading call stacks in the Debug Control view