reloader should survive SyntaxError

gunicorn/util.py

@@ -532,3 +532,15 @@ def warn(msg):
 
     print("!!!\n", file=sys.stderr)
     sys.stderr.flush()
+
+
+def make_fail_app(msg):
+
+    def app(environ, start_response):
+        start_response("500 Internal Server Error", [
+            ("Content-Type", "text/plain"),
+            ("Content-Length", str(len(msg)))
+        ])
+        return [msg]
+
+    return app

gunicorn/workers/base.py

@@ -8,6 +8,7 @@
 import signal
 import sys
 import time
+import traceback
 from random import randint
 
 
@@ -116,14 +117,29 @@ def changed(fname):
 
         self.init_signals()
 
-        self.wsgi = self.app.wsgi()
-
         self.cfg.post_worker_init(self)
 
+        self.load_wsgi()
+
         # Enter main run loop
         self.booted = True
         self.run()
 
+    def load_wsgi(self):
+        try:
+            self.wsgi = self.app.wsgi()
+        except SyntaxError as e:
+            if not self.cfg.reload:
+                raise
+
+            self.log.exception(e)
+
+            exc_type, exc_val, exc_tb = sys.exc_info()
+            self.reloader.add_extra_file(exc_val.filename)
+
+            tb_string = traceback.format_exc(exc_tb)
+            self.wsgi = util.make_fail_app(tb_string)
+
     def init_signals(self):
         # reset signaling
         [signal.signal(s, signal.SIG_DFL) for s in self.SIGNALS]