Optimizing overall performance under heavy load by temporarily rejecting new sessions that will likely not finish successfully anyway.

acs.coffee

@@ -16,6 +16,10 @@ OBJECT_REGEX = /\.$/
 INSTANCE_REGEX = /\.[\d]+\.$/
 
 
+# Used to reject new TR-069 sessions when under load
+holdUntil = Date.now()
+
+
 applyConfigurations = (currentRequest, taskList) ->
   if taskList.length
     util.log("#{currentRequest.deviceId}: Presets discrepancy found")
@@ -129,9 +133,16 @@ updateDevice = (currentRequest, actions, callback) ->
 
 
 runTask = (currentRequest, task, methodResponse) ->
+  timeDiff = process.hrtime()
   tasks.task(task, methodResponse, (err, status, cwmpResponse, deviceUpdates) ->
     # TODO handle error
-    updateDevice(currentRequest, deviceUpdates)
+    updateDevice(currentRequest, deviceUpdates, (err) ->
+      util.error(err) if err?
+
+      timeDiff = process.hrtime(timeDiff)[0] + 1
+      if timeDiff > 3 # in seconds
+        # Server under load. Hold new sessions temporarily.
+        holdUntil = Math.max(Date.now() + timeDiff * 2000, holdUntil)
 
       switch status
         when tasks.STATUS_FINISHED
@@ -160,6 +171,7 @@ runTask = (currentRequest, task, methodResponse) ->
         else
           throw Error('Unknown task status')
     )
+  )
 
 
 isTaskExpired = (task) ->
@@ -263,6 +275,12 @@ listener = (httpRequest, httpResponse) ->
 
     if cwmpRequest.methodRequest?
       if cwmpRequest.methodRequest.type is 'Inform'
+        if Date.now() < holdUntil
+          # Ask CPE to retry in 5 mins
+          res = {code : 503, headers : {'Content-Length' : 0, 'Retry-After' : 300}, data : ''}
+          writeResponse(currentRequest, res)
+          return
+
         cwmpResponse.methodResponse = {type : 'InformResponse'}
 
         if config.LOG_INFORMS