--- a/CHANGES.txt	Sat Jul 02 13:52:52 2022 -0400
+++ b/CHANGES.txt	Sat Jul 02 14:04:00 2022 -0400
@@ -176,6 +176,9 @@
   i18n object is now also correctly set for the mail interface:
   previously the 'language' setting in the [mailgw] section seems to
   have been ignored. Thanks to Marcus Priesch for the patch.
+- issue2551212 - speed up wsgi interface by caching the tracker
+  instance. Hidden behind a feature flag. See upgrading.txt for
+  details. (Marcus Priesch with feature flag by John Rouillard)
 
 2021-07-13 2.1.0
 

--- a/doc/upgrading.txt	Sat Jul 02 13:52:52 2022 -0400
+++ b/doc/upgrading.txt	Sat Jul 02 14:04:00 2022 -0400
@@ -209,6 +209,25 @@
 of ps or shell history. The new password will be encrypted using the
 default encryption method (usually pbkdf2).
 
+Enable performance improvement for wsgi mode (optional)
+-------------------------------------------------------
+
+There is an experimental wsgi performance improvement mode that caches
+the loaded roundup instance. This eliminates disk reads that are
+incurred on each connection. In one report it improves speed by a
+factor of 2 to 3 times. To enable this you should add a feature flag
+to your Roundup wsgi wrapper (see the file
+``.../share/frontends/wsgi.py``) so it looks like::
+
+   feature_flags = { "cache_tracker": "" }
+   app =  RequestDispatcher(tracker_home, feature_flags=feature_flags)
+
+to enable this mode. Note that this is experimental and was added
+during the 2.2.0 beta period, so it is enabled using a feature flag.
+If you use this and it works for you please followup with an email to
+the roundup-users at lists.sourceforge.net mailing list so we can
+enable it by default in a future release.
+
 Migrating from 2.0.0 to 2.1.0
 =============================
 

--- a/frontends/wsgi.py	Sat Jul 02 13:52:52 2022 -0400
+++ b/frontends/wsgi.py	Sat Jul 02 14:04:00 2022 -0400
@@ -12,5 +12,10 @@
 # Set the path to tracker home.
 tracker_home = '/path/to/tracker'
 
+# Enable the feature flag to speed up wsgi response by caching the
+#   Roundup tracker instance on startup. See upgrading.txt for
+#   more info.
+feature_flags =  { "cache_tracker": "" }
+
 # Definition signature for app: app(environ, start_response):
-app =  RequestDispatcher(tracker_home)
+app =  RequestDispatcher(tracker_home= feature_flags=feature_flags)

--- a/roundup/cgi/wsgi_handler.py	Sat Jul 02 13:52:52 2022 -0400
+++ b/roundup/cgi/wsgi_handler.py	Sat Jul 02 14:04:00 2022 -0400
@@ -74,17 +74,24 @@
 
 
 class RequestDispatcher(object):
-    def __init__(self, home, debug=False, timing=False, lang=None):
+    def __init__(self, home, debug=False, timing=False, lang=None,
+                 feature_flags=None):
         assert os.path.isdir(home), '%r is not a directory' % (home,)
         self.home = home
         self.debug = debug
         self.timing = timing
+        self.feature_flags= feature_flags or {}
+        self.tracker = None
         if lang:
             self.translator = TranslationService.get_translation(lang,
                 tracker_home=home)
         else:
             self.translator = None
-        self.preload()
+
+        if "cache_tracker" in self.feature_flags:
+            self.tracker = roundup.instance.open(self.home, not self.debug)
+        else:
+            self.preload()
 
     def __call__(self, environ, start_response):
         """Initialize with `apache.Request` object"""
@@ -116,8 +123,8 @@
         else:
             form = BinaryFieldStorage(fp=environ['wsgi.input'], environ=environ)
 
-        with self.get_tracker() as tracker:
-            client = tracker.Client(tracker, request, environ, form,
+        if "cache_tracker" in self.feature_flags:
+            client = self.tracker.Client(self.tracker, request, environ, form,
                                     self.translator)
             try:
                 client.main()
@@ -125,6 +132,16 @@
                 request.start_response([('Content-Type', 'text/html')], 404)
                 request.wfile.write(s2b('Not found: %s' % 
                                         html_escape(client.path)))
+        else:
+            with self.get_tracker() as tracker:
+                client = tracker.Client(tracker, request, environ, form,
+                                        self.translator)
+                try:
+                    client.main()
+                except roundup.cgi.client.NotFound:
+                    request.start_response([('Content-Type', 'text/html')], 404)
+                    request.wfile.write(s2b('Not found: %s' % 
+                                            html_escape(client.path)))
 
         # all body data has been written using wfile
         return []

--- a/test/test_liveserver.py	Sat Jul 02 13:52:52 2022 -0400
+++ b/test/test_liveserver.py	Sat Jul 02 14:04:00 2022 -0400
@@ -38,7 +38,7 @@
 _py3 = sys.version_info[0] > 2
 
 @skip_requests
-class SimpleTest(LiveServerTestCase):
+class WsgiSetup(LiveServerTestCase):
     # have chicken and egg issue here. Need to encode the base_url
     # in the config file but we don't know it until after
     # the server is started and has read the config.ini.
@@ -103,7 +103,8 @@
         i18n.DOMAIN = cls.backup_domain
 
     def create_app(self):
-        '''The wsgi app to start'''
+        '''The wsgi app to start - no feature_flags set.'''
+
         if _py3:
             return validator(RequestDispatcher(self.dirname))
         else:
@@ -112,6 +113,11 @@
             return RequestDispatcher(self.dirname)
 
 
+class BaseTestCases(WsgiSetup):
+    """Class with all tests to run against wsgi server. Is reused when
+       wsgi server is started with various feature flags
+    """
+
     def test_start_page(self):
         """ simple test that verifies that the server can serve a start page.
         """
@@ -973,4 +979,16 @@
         self.assertEqual(r.status_code, 201)
         print(r.status_code)
 
-
+class TestFeatureFlagCacheTrackerOn(BaseTestCases, WsgiSetup):
+    """Class to run all test in BaseTestCases with the cache_tracker
+       feature flag enabled when starting the wsgi server
+    """
+    def create_app(self):
+        '''The wsgi app to start with feature flag enabled'''
+        ff = { "cache_tracker": "" }
+        if _py3:
+            return validator(RequestDispatcher(self.dirname, feature_flags=ff))
+        else:
+            # wsgiref/validator.py InputWrapper::readline is broke and
+            # doesn't support the max bytes to read argument.
+            return RequestDispatcher(self.dirname, feature_flags=ff)