I was confused for a while when seeing the thread stacks dumped by the faulthandler module.  (See issue 19293.)

I propose the following tweaks of the output to make this more obvious. The first chunk changes the header written when called as _Py_DumpTraceback(), the second change the per-thread headers printed by _Py_DumpTracebackThreads().

diff -r 02f6922e6a7e Python/traceback.c
--- a/Python/traceback.c        Sat Oct 19 17:04:25 2013 -0700
+++ b/Python/traceback.c        Sat Oct 19 17:19:29 2013 -0700
@@ -603,7 +603,7 @@
     unsigned int depth;

     if (write_header)
-        PUTS(fd, "Traceback (most recent call first):\n");
+        PUTS(fd, "Stack (most recent call first):\n");

     frame = _PyThreadState_GetFrame(tstate);
     if (frame == NULL)
@@ -642,7 +642,7 @@
     else
         PUTS(fd, "Thread 0x");
     dump_hexadecimal(sizeof(long)*2, (unsigned long)tstate->thread_id, fd);
-    PUTS(fd, ":\n");
+    PUTS(fd, " (most recent call first):\n");
 }

 const char*

BTW, another oddity in traceback.c: dump_hexadecimal() has the "int fd" argument at the end, while all other dump_*() functions have it at the front -- even its cousin dump_decimal(). Here's a patch that includes a fix.

You must update unit tests in test_faulthandler.

New patch, with fixed test.

TBH now I'm getting worried that other programs may exist that parse this format and will get confused.

> TBH now I'm getting worried that other programs may exist that parse this format and will get confused.

A program parsing faulthandler output? Seriously? It would be nice, but I don't know any.

Anyway, such program would probably use a regex to parse the output, and it's very easy to support Python 3.3 format and patched (future 3.4) format.

> New patch, with fixed test.

Thanks. The patch looks good to me, you can push it.

New changeset cc8c37b5b449 by Guido van Rossum in branch 'default':
Issue 19306: Add extra hints to faulthandler stack dumps that they are upside down.
http://hg.python.org/cpython/rev/cc8c37b5b449

On Victor's authority, committed. I've also (separately) committed some doc changes.

Thanks. "(most recent call first)" was already present in some cases, but I forgot to mention it in all cases.