Issue #23430: Stop socketserver from catching SystemExit etc from handlers

Also make handle_error() consistently output to stderr, and fix the
documentation.

2 files changed, 15 insertions, 2 deletions

diff --git a/Doc/library/socketserver.rst b/Doc/library/socketserver.rst
index f0cfc80..aaaa61e 100644
--- a/Doc/library/socketserver.rst
+++ b/Doc/library/socketserver.rst
@@ -304,7 +304,11 @@ Server Objects
       This function is called if the :meth:`~BaseRequestHandler.handle`
       method of a :attr:`RequestHandlerClass` instance raises
       an exception.  The default action is to print the traceback to
-      standard output and continue handling further requests.
+      standard error and continue handling further requests.
+
+      .. versionchanged:: 3.6
+         Now only called for exceptions derived from the :exc:`Exception`
+         class.
 
 
    .. method:: handle_timeout()
diff --git a/Doc/whatsnew/3.6.rst b/Doc/whatsnew/3.6.rst
index 8b879de..5c02b7d 100644
--- a/Doc/whatsnew/3.6.rst
+++ b/Doc/whatsnew/3.6.rst
@@ -334,7 +334,16 @@ Changes in the Python API
 
 * When a relative import is performed and no parent package is known, then
   :exc:`ImportError` will be raised. Previously, :exc:`SystemError` could be
-  raised. (Contribute by Brett Cannon in :issue:`18018`.)
+  raised. (Contributed by Brett Cannon in :issue:`18018`.)
+
+* Servers based on the :mod:`socketserver` module, including those
+  defined in :mod:`http.server`, :mod:`xmlrpc.server` and
+  :mod:`wsgiref.simple_server`, now only catch exceptions derived
+  from :exc:`Exception`. Therefore if a request handler raises
+  an exception like :exc:`SystemExit` or :exc:`KeyboardInterrupt`,
+  :meth:`~socketserver.BaseServer.handle_error` is no longer called, and
+  the exception will stop a single-threaded server. (Contributed by
+  Martin Panter in :issue:`23430`.)
 
 
 Changes in the C API