An NSPR thread.
#include <prthread.h> typedef struct PRThread PRThread;
In NSPR, a thread is represented by a pointer to an opaque structure of type
PRThread. This pointer is a required parameter for most of the functions that operate on threads.
PRThread* is the successful result of creating a new thread. The identifier remains valid until it returns from its root function and, if the thread was created joinable, is joined.