From 728b92f0ff320b36b322c2b43baf44f5ea4bd059 Mon Sep 17 00:00:00 2001
From: Clint Armstrong <clint@clintarmstrong.net>
Date: Mon, 14 Sep 2015 08:40:20 -0400
Subject: [PATCH] first attempt at lessening mysql load

---
 doc/Extensions/Poller-Service.md |  3 ++-
 poller-service.py                | 15 ++++++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/doc/Extensions/Poller-Service.md b/doc/Extensions/Poller-Service.md
index 6d33e27b92..cb6af28e86 100644
--- a/doc/Extensions/Poller-Service.md
+++ b/doc/Extensions/Poller-Service.md
@@ -4,7 +4,7 @@
 
 The Poller service is an alternative to polling and discovery cron jobs and provides support for distributed polling without memcache. It is multi-threaded and runs continuously discovering and polling devices with the oldest data attempting to honor the polling frequency configured in `config.php`. This service replaces all the required cron jobs except for `/opt/librenms/daily.sh` and `/opt/librenms/alerts.php`.
 
-Configure the maximum number of threads for the service in `$config['poller_service_workers']`. Configure the minimum desired polling frequency in `$config['poller_service_poll_frequency']` and the minimum desired discovery frequency in `$config['poller_service_discover_frequency']`. The service will not poll or discover devices which have data newer than this this configured age in seconds. Configure how frequently the service will attempt to poll devices which are down in `$config['poller_service_down_retry']`.
+Configure the maximum number of threads for the service in `$config['poller_service_workers']`. Configure the minimum desired polling frequency in `$config['poller_service_poll_frequency']` and the minimum desired discovery frequency in `$config['poller_service_discover_frequency']`. The service will not poll or discover devices which have data newer than this this configured age in seconds. Configure how frequently the service will attempt to poll devices which are down in `$config['poller_service_down_retry']`. If you have enough pollers that the worker threads run out of work, the service will query looking for devices every `$config['poller_service_retry_query']` seconds.
 
 The poller service is designed to gracefully degrade. If not all devices can be polled within the configured frequency, the service will continuously poll devices refreshing as frequently as possible using the configured number of threads.
 
@@ -18,6 +18,7 @@ $config['poller_service_workers']                        = 16;
 $config['poller_service_poll_frequency']                 = 300;
 $config['poller_service_discover_frequency']             = 21600;
 $config['poller_service_down_retry']                     = 60;
+$config['poller_service_retry_query']                    = 1;
 ```
 
 ## Distributed Polling
diff --git a/poller-service.py b/poller-service.py
index ce93108e37..fff7968d78 100755
--- a/poller-service.py
+++ b/poller-service.py
@@ -164,6 +164,13 @@ try:
 except KeyError:
     down_retry = 60
 
+try:
+    retry_query = int(config['poller_service_retry_query'])
+    if retry_query == 0:
+        retry_query = 1
+except KeyError:
+    retry_query = 1
+
 db = DB()
 
 
@@ -232,16 +239,22 @@ dev_query = ('SELECT device_id, status,
 next_update = datetime.now() + timedelta(minutes=1)
 devices_scanned = 0
 
+dont_query_until = datetime.fromtimestamp(0)
 
 def poll_worker():
     global dev_query
     global devices_scanned
+    global dont_query_until
     thread_id = threading.current_thread().name
     db = DB()
     while True:
+        if datetime.now() < dont_query_until:
+            time.sleep(1)
+            continue
+
         dev_row = db.query(dev_query)
         if len(dev_row) < 1:
-            # Sleep 1 second after getting an empty query, don't hammer the sql server for no reason.
+            dont_query_until = datetime.now() + timedelta(seconds=retry_query)
             time.sleep(1)
             continue