add thread pool stats

This is a merge of 3b123da from phobos182/collectd-elasticsearch into
wyattwalter/collectd-elasticsearch since the upstream PR phobos182#13 was never merged

elasticsearch.py

@@ -191,6 +191,7 @@ def configure_callback(conf):
 
     log_verbose('Configured with host=%s, port=%s' % (ES_HOST, ES_PORT))
 
+
 def fetch_url(url):
     try:
         result = json.load(urllib2.urlopen(url, timeout=10))
@@ -208,16 +209,25 @@ def fetch_stats():
     version = server_info['version']['number']
 
     if StrictVersion(version) >= StrictVersion('1.0.0'):
-        ES_URL = base_url + '_nodes/_local/stats/transport,http,process,jvm,indices,breaker'
+        ES_URL = base_url + '_nodes/_local/stats/transport,http,process,jvm,indices,breaker,thread_pool'
         STATS_CUR = dict(STATS.items() + STATS_ES1X.items())
         if StrictVersion(version) >= StrictVersion('1.4.0'):
             STATS_CUR = dict(STATS_CUR.items() + STATS_ES14.items())
         else:
             STATS_CUR = dict(STATS_CUR.items() + STATS_ES13.items())
     else:
-        ES_URL = base_url + '_cluster/nodes/_local/stats?http=true&process=true&jvm=true&transport=true'
+        ES_URL = base_url + '_cluster/nodes/_local/stats?http=true&process=true&jvm=true&transport=true&thread_pool=true'
         STATS_CUR = dict(STATS.items() + STATS_ES09.items())
 
+    # add info on thread pools
+    for pool in ['generic', 'index', 'get', 'snapshot', 'merge', 'optimize', 'bulk', 'warmer', 'flush', 'search', 'refresh']:
+      for attr in ['threads', 'queue', 'active', 'largest']:
+        path = 'thread_pool.{0}.{1}'.format(pool, attr)
+        STATS_CUR[path] = Stat("gauge", 'nodes.%s.{0}'.format(path))
+      for attr in ['completed', 'rejected']:
+        path = 'thread_pool.{0}.{1}'.format(pool, attr)
+        STATS_CUR[path] = Stat("counter", 'nodes.%s.{0}'.format(path))
+
     result = fetch_url(ES_URL)
 
     ES_CLUSTER = result['cluster_name']