bpo-36084: Add native thread ID to threading.Thread objects (GH-11993)

Python/thread_nt.h

@@ -143,6 +143,8 @@ LeaveNonRecursiveMutex(PNRMUTEX mutex)
 
 unsigned long PyThread_get_thread_ident(void);
 
+unsigned long PyThread_get_thread_native_id(void);
+
 /*
  * Initialization of the C package, should not be needed.
  */
@@ -227,6 +229,20 @@ PyThread_get_thread_ident(void)
     return GetCurrentThreadId();
 }
 
+/*
+ * Return the native Thread ID (TID) of the calling thread.
+ * The native ID of a thread is valid and guaranteed to be unique system-wide
+ * from the time the thread is created until the thread has been terminated.
+ */
+unsigned long
+PyThread_get_thread_native_id(void)
+{
+    if (!initialized)
+        PyThread_init_thread();
+
+    return GetCurrentThreadId();
+}
+
 void _Py_NO_RETURN
 PyThread_exit_thread(void)
 {

Python/thread_pthread.h

@@ -12,6 +12,12 @@
 #endif
 #include <signal.h>
 
+#if defined(__linux__)
+#include <sys/syscall.h>
+#elif defined(__FreeBSD__)
+#include <pthread_np.h>
+#endif
+
 /* The POSIX spec requires that use of pthread_attr_setstacksize
    be conditional on _POSIX_THREAD_ATTR_STACKSIZE being defined. */
 #ifdef _POSIX_THREAD_ATTR_STACKSIZE
@@ -302,6 +308,27 @@ PyThread_get_thread_ident(void)
     return (unsigned long) threadid;
 }
 
+unsigned long
+PyThread_get_thread_native_id(void)
+{
+    if (!initialized)
+        PyThread_init_thread();
+#ifdef __APPLE__
+    uint64_t native_id;
+    pthread_threadid_np(NULL, &native_id);
+#elif defined(__linux__)
+    pid_t native_id;
+    native_id = syscall(__NR_gettid);
+#elif defined(__FreeBSD__)
+    pid_t native_id;
+    native_id = pthread_getthreadid_np();
+#else
+    unsigned long native_id;
+    native_id = 0;
+#endif
+    return (unsigned long) native_id;
+}
+
 void _Py_NO_RETURN
 PyThread_exit_thread(void)
 {