From c9a56e248d0312568318fee0b758e8d59e0db215 Mon Sep 17 00:00:00 2001
From: Clint Armstrong <clint@clintarmstrong.net>
Date: Fri, 17 Jul 2015 13:33:24 -0400
Subject: [PATCH] index and limit

---
 poller-service.py  | 9 ++++-----
 sql-schema/065.sql | 2 ++
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/poller-service.py b/poller-service.py
index 0ca3b5cd99..bbcfa76172 100755
--- a/poller-service.py
+++ b/poller-service.py
@@ -199,7 +199,8 @@ dev_query = ('SELECT device_id, status,
              'AND ( last_poll_attempted < DATE_SUB(NOW(), INTERVAL {2} SECOND )  '
              '  OR last_poll_attempted IS NULL )                                 '
              '{3}                                                                '
-             'ORDER BY next_poll asc                                             ').format(poll_frequency,
+             'ORDER BY next_poll asc                                             '
+             'LIMIT 5                                                            ').format(poll_frequency,
                                                                                            discover_frequency,
                                                                                            down_retry,
                                                                                            poller_group)
@@ -251,11 +252,9 @@ while True:
         # add queue lock, so we lock the next device against any other pollers
         # if this fails, the device is locked by another poller already
         if not getLock('queued.{}'.format(device_id)):
-            time.sleep(.5)
             continue
         if not lockFree('polling.{}'.format(device_id)):
             releaseLock('queued.{}'.format(device_id))
-            time.sleep(.5)
             continue
 
         if next_poll and next_poll > datetime.now():
@@ -278,9 +277,9 @@ while True:
         # If we made it this far, break out of the loop and query again.
         break
 
-    # Looping with no break causes the service to be killed by init.
     # This point is only reached if the query is empty, so sleep half a second before querying again.
     time.sleep(.5)
 
-    # Make sure we're not holding any device queue locks in this connection before querying again.
+    # Make sure we're not holding any device queue locks in this connection before querying again
+    # by locking a different string.
     getLock('unlock.{}'.format(config['distributed_poller_name']))
diff --git a/sql-schema/065.sql b/sql-schema/065.sql
index ab64beca95..4fb76d358d 100644
--- a/sql-schema/065.sql
+++ b/sql-schema/065.sql
@@ -1,3 +1,5 @@
 DELETE n1 FROM pollers n1, pollers n2 WHERE n1.last_polled < n2.last_polled and n1.poller_name = n2.poller_name;
 ALTER TABLE pollers ADD PRIMARY KEY (poller_name);
 ALTER TABLE `devices` ADD `last_poll_attempted` timestamp NULL DEFAULT NULL AFTER `last_polled`;
+ALTER TABLE `devices` ADD INDEX `last_polled` (`last_polled`);
+ALTER TABLE `devices` ADD INDEX `last_poll_attempted` (`last_poll_attempted`);