registry: preload entrypoints before caching

When profiling a JJB run against Wikimedia configuration files [0], I
noticed a lot of calls to package_resource trying to figure out the
version.

Years ago, I already added coded to cache the entrypoints, unfortunately
only the entry point definition got cached not the underlying function.
Thus each entry point ends up invoking a load() which dramatically slow
down JJB.

A low hanging fruit is to invoke load() and cache the returned function.
Doing so, the run time goes down from 28 seconds down to 17 seconds.

[0] https://gerrit.wikimedia.org/g/integration/config/+/master/jjb/
Change-Id: I336b556f28328d8acbdd71c43c8775d55c3720d8

1 files changed, 3 insertions, 2 deletions

diff --git a/jenkins_jobs/registry.py b/jenkins_jobs/registry.py
index 2c997737..38ee4a55 100644
--- a/jenkins_jobs/registry.py
+++ b/jenkins_jobs/registry.py
@@ -184,6 +184,7 @@ class ModuleRegistry(object):
         # Look for a component function defined in an entry point
         eps = self._entry_points_cache.get(component_list_type)
         if eps is None:
+            logging.debug("Caching entrypoints for %s" % component_list_type)
             module_eps = []
             # auto build entry points by inferring from base component_types
             mod = pkg_resources.EntryPoint(
@@ -245,7 +246,7 @@ class ModuleRegistry(object):
                         "name: '{1}'".format(component_type, name)
                     )
 
-                eps[module_ep.name] = module_ep
+                eps[module_ep.name] = module_ep.load()
 
             # cache both sets of entry points
             self._entry_points_cache[component_list_type] = eps
@@ -268,7 +269,7 @@ class ModuleRegistry(object):
                 # the arguments are interpolated into the real defn.
                 self.dispatch(component_type, xml_parent, b, component_data)
         elif name in eps:
-            func = eps[name].load()
+            func = eps[name]
             func(self, xml_parent, component_data)
         else:
             raise JenkinsJobsException(