Patch to Google Course Builder v1.4.1, adding caching of the bytecode of Jinja2 templates. Change to the root dir of your course builder installation and use patch -p2 < (this file)

coursebuilder-bytecodecache-1.4.1.patch

diff --git a/coursebuilder/common/jinja_filters.py b/coursebuilder/common/jinja_filters.py
index 2bb6d17..a8a6261 100644
--- a/coursebuilder/common/jinja_filters.py
+++ b/coursebuilder/common/jinja_filters.py
@@ -17,8 +17,10 @@
 __author__ = 'John Orr (jorr@google.com)'
 
 import jinja2
+from jinja2.bccache import BytecodeCache
 import safe_dom
 import tags
+from models.models import MemcacheManager
 
 
 def finalize(x):
@@ -52,3 +54,59 @@ def gcb_tags(data):
         return jinja2.utils.Markup(tags.html_to_safe_dom(data))
     else:
         return jinja2.utils.Markup(data)
+
+
+class ClearableMemcachedBytecodeCache(BytecodeCache):
+    """Requires a fancy memcache client, like Google App Engine's,
+    that supports namespaces.  Requires get, set, add, and incr.
+
+    When you call .clear(), the entries previously stored through
+    this object become inaccessible through it, although they
+    are not guaranteed to be evicted from the underlying memcached
+    immediately.
+    """
+    __author__ = 'Thomas Grenfell Smith (thomathom@gmail.com)'
+
+    def __init__(self, client, namespace=None,
+            prefix='jinja2:bytecode:', timeout=None,
+            ignore_memcache_errors=True):
+        self.namespace = namespace
+        self.client = client
+        self.prefix = prefix
+        self.timeout = timeout
+        self.ignore_memcache_errors = ignore_memcache_errors
+
+    def _get_key(self, bucket):
+        generation_key = self.prefix + '__generation__'
+        generation = '1'
+        if not self.client.add(generation_key, generation, namespace=self.namespace):
+            generation = self.client.get(generation_key,
+                    namespace=self.namespace)
+
+        return '%s:%s:%s' % (self.prefix, generation, bucket.key)
+
+    def clear(self):
+        generation_key = self.prefix + '__generation__'
+        if not self.client.incr(generation_key, 1, namespace=self.namespace):
+            self.client.set(generation_key, '1', namespace=self.namespace)
+
+    def load_bytecode(self, bucket):
+        try:
+            code = self.client.get(self._get_key(bucket),
+                namespace=self.namespace)
+        except Exception:
+            if not self.ignore_memcache_errors:
+                raise
+            code = None
+        if code is not None:
+            bucket.bytecode_from_string(code)
+
+    def dump_bytecode(self, bucket):
+        args = (self._get_key(bucket), bucket.bytecode_to_string())
+        if self.timeout is not None:
+            args += (self.timeout,)
+        try:
+            self.client.set(*args, namespace=self.namespace)
+        except Exception:
+            if not self.ignore_memcache_errors:
+                raise
diff --git a/coursebuilder/models/models.py b/coursebuilder/models/models.py
index 74a794f..36efb68 100644
--- a/coursebuilder/models/models.py
+++ b/coursebuilder/models/models.py
@@ -96,7 +96,17 @@ class MemcacheManager(object):
         if CAN_USE_MEMCACHE.value:
             if not namespace:
                 namespace = appengine_config.DEFAULT_NAMESPACE_NAME
-            memcache.incr(key, delta, namespace=namespace, initial_value=0)
+            return memcache.incr(key, delta, namespace=namespace, initial_value=0)
+
+    @classmethod
+    def add(cls, key, value, ttl=DEFAULT_CACHE_TTL_SECS, namespace=None):
+        """Adds an item in memcache if memcache is enabled."""
+        if CAN_USE_MEMCACHE.value:
+            CACHE_PUT.inc()
+            if not namespace:
+                namespace = appengine_config.DEFAULT_NAMESPACE_NAME
+            return memcache.add(
+                key, value, ttl, namespace=namespace)
 
     @classmethod
     def delete(cls, key, namespace=None):
diff --git a/coursebuilder/models/vfs.py b/coursebuilder/models/vfs.py
index 2477e94..6fa8473 100644
--- a/coursebuilder/models/vfs.py
+++ b/coursebuilder/models/vfs.py
@@ -156,6 +156,8 @@ class LocalReadOnlyFileSystem(object):
         jinja_environment = jinja2.Environment(
             autoescape=True, finalize=jinja_filters.finalize,
             extensions=['jinja2.ext.i18n'],
+            bytecode_cache=jinja_filters.ClearableMemcachedBytecodeCache(
+                MemcacheManager),
             loader=jinja2.FileSystemLoader(physical_dir_names))
         jinja_environment.filters['js_string'] = jinja_filters.js_string
 
@@ -511,6 +513,8 @@ class DatastoreBackedFileSystem(object):
         jinja_environment = jinja2.Environment(
             autoescape=True, finalize=jinja_filters.finalize,
             extensions=['jinja2.ext.i18n'],
+            bytecode_cache=jinja_filters.ClearableMemcachedBytecodeCache(
+                MemcacheManager, namespace=self._ns),
             loader=VirtualFileSystemTemplateLoader(
                 self, self._logical_home_folder, dir_names))
         jinja_environment.filters['js_string'] = jinja_filters.js_string
diff --git a/coursebuilder/modules/admin/admin.py b/coursebuilder/modules/admin/admin.py
index 3cdaa87..708546e 100644
--- a/coursebuilder/modules/admin/admin.py
+++ b/coursebuilder/modules/admin/admin.py
@@ -34,6 +34,7 @@ from models import config
 from models import counters
 from models import custom_modules
 from models import roles
+from models.models import MemcacheManager
 from models.config import ConfigProperty
 import modules.admin.config
 from modules.admin.config import ConfigPropertyEditor
@@ -130,6 +131,8 @@ class AdminHandler(
         """Sets up an environment and Gets jinja template."""
         jinja_environment = jinja2.Environment(
             autoescape=True, finalize=jinja_filters.finalize,
+            bytecode_cache=jinja_filters.ClearableMemcachedBytecodeCache(
+                MemcacheManager),
             loader=jinja2.FileSystemLoader(dirs + [os.path.dirname(__file__)]))
         jinja_environment.filters['js_string'] = jinja_filters.js_string
         return jinja_environment.get_template(template_name)
diff --git a/coursebuilder/modules/dashboard/dashboard.py b/coursebuilder/modules/dashboard/dashboard.py
index d738e1e..043d6cb 100644
--- a/coursebuilder/modules/dashboard/dashboard.py
+++ b/coursebuilder/modules/dashboard/dashboard.py
@@ -35,7 +35,7 @@ from models import roles
 from models import transforms
 from models import utils
 from models import vfs
-from models.models import Student
+from models.models import Student, MemcacheManager
 from course_settings import CourseSettingsHandler
 from course_settings import CourseSettingsRESTHandler
 import filer
@@ -120,6 +120,9 @@ class DashboardHandler(
 
         jinja_environment = jinja2.Environment(
             autoescape=True, finalize=jinja_filters.finalize,
+            bytecode_cache=jinja_filters.ClearableMemcachedBytecodeCache(
+                MemcacheManager,
+                namespace=self.app_context.get_namespace_name()),
             loader=jinja2.FileSystemLoader(dirs + [os.path.dirname(__file__)]))
         jinja_environment.filters['js_string'] = jinja_filters.js_string
 
diff --git a/coursebuilder/modules/oeditor/oeditor.py b/coursebuilder/modules/oeditor/oeditor.py
index d629b72..17709a1 100644
--- a/coursebuilder/modules/oeditor/oeditor.py
+++ b/coursebuilder/modules/oeditor/oeditor.py
@@ -26,6 +26,7 @@ from controllers import utils
 import jinja2
 from models import custom_modules
 from models import transforms
+from models.models import MemcacheManager
 import webapp2
 
 # a set of YUI and inputex modules required by the editor
@@ -151,6 +152,9 @@ class PopupHandler(webapp2.RequestHandler, utils.ReflectiveRequestHandler):
 
         jinja_environment = jinja2.Environment(
             autoescape=True, finalize=jinja_filters.finalize,
+            bytecode_cache=jinja_filters.ClearableMemcachedBytecodeCache(
+                MemcacheManager,
+                namespace=self.app_context.get_namespace_name()),
             loader=jinja2.FileSystemLoader(dirs + [os.path.dirname(__file__)]))
         jinja_environment.filters['js_string'] = jinja_filters.js_string