(partially fix #90 too) using a simple Alarm (SIGNAL) when exec-timeout

Introducing a timer (in this case 60 seconds) to ensure that the
execution time of the analysis takes less than 60 seconds. This
is a simple and standard POSIX signal handler. If the timeout
is reached, the module will process the next one.

This approach fixes the specific issues we have currently
with some inputs where the sentiment analysis takes too much time. This
fix should be improved and be more generic:

 - Introducing statistics of content which timeouts.
 - Keeping a list/queue to further process those files using a different
   analysis approach. Maybe a set of "dirty" processes to handle the edge cases
   and to not impact the overall processing and analysis.
 - Make the timer configurable per module (at least for this one).

bin/SentimentAnalysis.py

@@ -54,9 +54,9 @@ def Analyse(message, server):
         the_time = datetime.time(getattr(the_time, 'hour'), 0, 0)
         combined_datetime = datetime.datetime.combine(the_date, the_time)
         timestamp = calendar.timegm(combined_datetime.timetuple())
-    
+
         sentences = tokenize.sent_tokenize(p_content.decode('utf-8', 'ignore'))
-    
+
         if len(sentences) > 0:
             avg_score = {'neg': 0.0, 'neu': 0.0, 'pos': 0.0, 'compoundPos': 0.0, 'compoundNeg': 0.0}
             neg_line = 0
@@ -74,8 +74,8 @@ def Analyse(message, server):
                              pos_line += 1
                      else:
                          avg_score[k] += ss[k]
-    
-    
+
+
             for k in avg_score:
                 if k == 'compoundPos':
                     avg_score[k] = avg_score[k] / (pos_line if pos_line > 0 else 1)
@@ -83,15 +83,15 @@ def Analyse(message, server):
                     avg_score[k] = avg_score[k] / (neg_line if neg_line > 0 else 1)
                 else:
                     avg_score[k] = avg_score[k] / len(sentences)
-    
-    
+
+
             # In redis-levelDB: {} = set, () = K-V 
             # {Provider_set -> provider_i}
             # {Provider_TimestampInHour_i -> UniqID_i}_j
             # (UniqID_i -> PasteValue_i)
-    
+
             server.sadd('Provider_set', provider)
-    
+
             provider_timestamp = provider + '_' + str(timestamp)
             server.incr('UniqID')
             UniqID = server.get('UniqID')
@@ -100,7 +100,7 @@ def Analyse(message, server):
             server.set(UniqID, avg_score)
     else:
         print 'Dropped:', p_MimeType
-    
+
 
 def isJSON(content):
     try:
@@ -110,6 +110,16 @@ def isJSON(content):
     except Exception,e:
         return False
 
+import signal
+
+class TimeoutException(Exception):
+    pass
+
+def timeout_handler(signum, frame):
+    raise TimeoutException
+
+signal.signal(signal.SIGALRM, timeout_handler)
+
 if __name__ == '__main__':
     # If you wish to use an other port of channel, do not forget to run a subscriber accordingly (see launch_logs.sh)
     # Port of the redis instance used by pubsublogger
@@ -138,6 +148,12 @@ if __name__ == '__main__':
             publisher.debug("{} queue is empty, waiting".format(config_section))
             time.sleep(1)
             continue
-
-        Analyse(message, server)
+        signal.alarm(60)
+        try:
+            Analyse(message, server)
+        except TimeoutException:
+            print ("{0} processing timeout".format(message))
+            continue
+        else:
+            signal.alarm(0)