Add active worker count to buildmanager logs.

buildman/manager/basemanager.py

@@ -47,3 +47,9 @@ class BaseManager(object):
         one of: incomplete, error, complete. If incomplete, the job should be requeued.
     """
     raise NotImplementedError
+
+  def num_workers(self):
+    """ Returns the number of active build workers currently registered. This includes those
+        that are currently busy and awaiting more work.
+    """
+    raise NotImplementedError

buildman/manager/enterprise.py

@@ -70,3 +70,5 @@ class EnterpriseManager(BaseManager):
   def build_component_disposed(self, build_component, timed_out):
     self.build_components.remove(build_component)
 
+  def num_workers(self):
+    return len(self.build_components)

buildman/server.py

@@ -9,7 +9,7 @@ from aiowsgi import create_server as create_wsgi_server
 from flask import Flask
 from threading import Event
 from trollius.coroutines import From
-from datetime import datetime, timedelta
+from datetime import timedelta
 
 from buildman.jobutil.buildjob import BuildJob, BuildJobLoadException
 from data.queue import WorkQueue
@@ -137,7 +137,7 @@ class BuilderServer(object):
   @trollius.coroutine
   def _work_checker(self):
     while self._current_status == 'running':
-      logger.debug('Checking for more work')
+      logger.debug('Checking for more work for %d active workers', self._lifecycle_manager.num_workers())
       job_item = self._queue.get(processing_time=self._lifecycle_manager.setup_time())
       if job_item is None:
         logger.debug('No additional work found. Going to sleep for %s seconds', WORK_CHECK_TIMEOUT)