bpo-37087: Adding native ID support for OpenBSD (GH-13654)

diff --git a/Doc/library/_thread.rst b/Doc/library/_thread.rst
index 48d36e8..26568dc 100644
--- a/Doc/library/_thread.rst
+++ b/Doc/library/_thread.rst
@@ -106,7 +106,7 @@
    Its value may be used to uniquely identify this particular thread system-wide
    (until the thread terminates, after which the value may be recycled by the OS).
 
-   .. availability:: Windows, FreeBSD, Linux, macOS.
+   .. availability:: Windows, FreeBSD, Linux, macOS, OpenBSD.
 
    .. versionadded:: 3.8
 
diff --git a/Doc/library/threading.rst b/Doc/library/threading.rst
index ffe6d04..7fb9ac9 100644
--- a/Doc/library/threading.rst
+++ b/Doc/library/threading.rst
@@ -82,7 +82,7 @@
    Its value may be used to uniquely identify this particular thread system-wide
    (until the thread terminates, after which the value may be recycled by the OS).
 
-   .. availability:: Windows, FreeBSD, Linux, macOS.
+   .. availability:: Windows, FreeBSD, Linux, macOS, OpenBSD.
 
    .. versionadded:: 3.8
 
@@ -355,7 +355,7 @@
          system-wide) from the time the thread is created until the thread
          has been terminated.
 
-      .. availability:: Windows, FreeBSD, Linux, macOS.
+      .. availability:: Require :func:`get_native_id` function.
 
       .. versionadded:: 3.8
 
diff --git a/Include/pythread.h b/Include/pythread.h
index c0f1eb9..84b79c8 100644
--- a/Include/pythread.h
+++ b/Include/pythread.h
@@ -26,7 +26,7 @@
 PyAPI_FUNC(void) _Py_NO_RETURN PyThread_exit_thread(void);
 PyAPI_FUNC(unsigned long) PyThread_get_thread_ident(void);
 
-#if defined(__APPLE__) || defined(__linux__) || defined(__FreeBSD__) || defined(_WIN32)
+#if defined(__APPLE__) || defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) || defined(_WIN32)
 #define PY_HAVE_THREAD_NATIVE_ID
 PyAPI_FUNC(unsigned long) PyThread_get_thread_native_id(void);
 #endif
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-05-30-17-33-55.bpo-37087.vElenE.rst b/Misc/NEWS.d/next/Core and Builtins/2019-05-30-17-33-55.bpo-37087.vElenE.rst
new file mode 100644
index 0000000..a45330f
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-05-30-17-33-55.bpo-37087.vElenE.rst
@@ -0,0 +1 @@
+Add native thread ID (TID) support to OpenBSD.
\ No newline at end of file
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index f57a1e7..740b521 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -16,6 +16,8 @@
 #   include <sys/syscall.h>     /* syscall(SYS_gettid) */
 #elif defined(__FreeBSD__)
 #   include <pthread_np.h>      /* pthread_getthreadid_np() */
+#elif defined(__OpenBSD__)
+#   include <unistd.h>          /* getthrid() */
 #endif
 
 /* The POSIX spec requires that use of pthread_attr_setstacksize
@@ -323,6 +325,9 @@
 #elif defined(__FreeBSD__)
     int native_id;
     native_id = pthread_getthreadid_np();
+#elif defined(__OpenBSD__)
+    pid_t native_id;
+    native_id = getthrid();
 #endif
     return (unsigned long) native_id;
 }