fixed scheduler bug, thanks Niphlod

VERSION

@@ -1 +1 @@
-Version 2.2.1 (2012-10-25 17:22:57) stable
+Version 2.2.1 (2012-10-26 15:49:42) stable

gluon/scheduler.py

@@ -63,7 +63,6 @@ import os
 import time
 import multiprocessing
 import sys
-import cStringIO
 import threading
 import traceback
 import signal
@@ -206,7 +205,6 @@ def executor(queue, task, out):
         if task.app:
             os.chdir(os.environ['WEB2PY_PATH'])
             from gluon.shell import env, parse_path_info
-            from gluon.dal import BaseAdapter
             from gluon import current
             level = logging.getLogger().getEffectiveLevel()
             logging.getLogger().setLevel(logging.WARN)
@@ -788,9 +786,9 @@ class Scheduler(MetaScheduler):
         #the scheduler): then it wasn't expired, but now it is
         db(st.status.belongs(
             (QUEUED, ASSIGNED)))(st.stop_time < now).update(status=EXPIRED)
-
+        
         all_available = db(st.status.belongs((QUEUED, ASSIGNED)))((st.times_run < st.repeats) | (st.repeats == 0))(st.start_time <= now)((st.stop_time == None) | (st.stop_time > now))(st.next_run_time <= now)(st.enabled == True)
-        limit = len(all_workers) * (50 / len(wkgroups))
+        limit = len(all_workers) * (50 / (len(wkgroups) or 1))
         #if there are a moltitude of tasks, let's figure out a maximum of tasks per worker.
         #this can be adjusted with some added intelligence (like esteeming how many tasks will
         #a worker complete before the ticker reassign them around, but the gain is quite small
@@ -804,11 +802,13 @@ class Scheduler(MetaScheduler):
 
         #let's freeze it up
         db.commit()
+        x = 0
         for group in wkgroups.keys():
             tasks = all_available(st.group_name==group).select(
                 limitby=(0, limit), orderby=st.next_run_time)
             #let's break up the queue evenly among workers
             for task in tasks:
+                x += 1
                 gname = task.group_name
                 ws = wkgroups.get(gname)
                 if ws:
@@ -827,10 +827,10 @@ class Scheduler(MetaScheduler):
 
         db.commit()
         #I didn't report tasks but I'm working nonetheless!!!!
-        if len(tasks) > 0:
+        if x > 0:
             self.empty_runs = 0
         logger.info('TICKER: workers are %s' % len(all_workers))
-        logger.info('TICKER: tasks are %s' % len(tasks))
+        logger.info('TICKER: tasks are %s' % x)
 
     def sleep(self):
         time.sleep(self.heartbeat * self.worker_status[1])