One more autoreload path tweak: set $PYTHONPATH just before exec,

whether autoreload is __main__ or not.

diff --git a/tornado/autoreload.py b/tornado/autoreload.py
index 84975067d0eb7bf6f40f42ed34c2bf918f040656..5baae0de3d581b14b43c6f781380320f1cdcb10f 100644 (file)
--- a/tornado/autoreload.py
+++ b/tornado/autoreload.py
@@ -31,28 +31,33 @@ from __future__ import absolute_import, division, with_statement
 import os
 import sys
 
+# sys.path handling
+# -----------------
+#
+# If a module is run with "python -m", the current directory (i.e. "")
+# is automatically prepended to sys.path, but not if it is run as
+# "path/to/file.py".  The processing for "-m" rewrites the former to
+# the latter, so subsequent executions won't have the same path as the
+# original.
+#
+# Conversely, when run as path/to/file.py, the directory containing
+# file.py gets added to the path, which can cause confusion as imports
+# may become relative in spite of the future import.
+#
+# We address the former problem by setting the $PYTHONPATH environment
+# variable before re-execution so the new process will see the correct
+# path.  We attempt to address the latter problem when tornado.autoreload
+# is run as __main__, although we can't fix the general case because
+# we cannot reliably reconstruct the original command line
+# (http://bugs.python.org/issue14208).
+
 if __name__ == "__main__":
-    # If this module is run with "python -m tornado.autoreload", the current
-    # directory is automatically prepended to sys.path, but not if it is
-    # run as "path/to/tornado/autoreload.py".  The processing for "-m" rewrites
-    # the former to the latter, so subsequent executions won't have the same
-    # path as the original.  Modify os.environ here to ensure that the
-    # re-executed process will have the same path.
-    #
-    # Conversely, when run as path/to/tornado/autoreload.py, the directory
-    # containing autoreload.py gets added to the path, but we don't want
-    # tornado modules importable at top level, so remove it.
-    #
     # This sys.path manipulation must come before our imports (as much
     # as possible - if we introduced a tornado.sys or tornado.os
     # module we'd be in trouble), or else our imports would become
     # relative again despite the future import.
     #
     # There is a separate __main__ block at the end of the file to call main().
-    path_prefix = '.' + os.pathsep
-    if (sys.path[0] == '' and
-        not os.environ.get("PYTHONPATH", "").startswith(path_prefix)):
-        os.environ["PYTHONPATH"] = path_prefix + os.environ.get("PYTHONPATH", "")
     if sys.path[0] == os.path.dirname(__file__):
         del sys.path[0]
 
@@ -181,6 +186,15 @@ def _reload():
         # ioloop.set_blocking_log_threshold so it doesn't fire
         # after the exec.
         signal.setitimer(signal.ITIMER_REAL, 0, 0)
+    # sys.path fixes: see comments at top of file.  If sys.path[0] is an empty
+    # string, we were (probably) invoked with -m and the effective path
+    # is about to change on re-exec.  Add the current directory to $PYTHONPATH
+    # to ensure that the new process sees the same path we did.
+    path_prefix = '.' + os.pathsep
+    if (sys.path[0] == '' and
+        not os.environ.get("PYTHONPATH", "").startswith(path_prefix)):
+        os.environ["PYTHONPATH"] = (path_prefix +
+                                    os.environ.get("PYTHONPATH", ""))
     if sys.platform == 'win32':
         # os.execv is broken on Windows and can't properly parse command line
         # arguments and executable name if they contain whitespaces. subprocess