I have a game server running on AppEngine for my iOS game "SkyWords". The
most cpu intensive and most commonly run method I have accounts for over 50%
of my cpu usage. That method queries for all the games a user is attached
to and returns them. If a user or any of their opponents haven't updated
one of the games the result will be the same.. so I implemented memcache to
see if I could cut down on cpu usage as I am creeping up to my quota limit.
Memcache doesn't seem to help much for me, but this is the first time I'm
trying to use it.. maybe I'm doing something stupid
Here is the method in question with irrelevant details stripped:
class GetActiveGameListHandler(SkyWordsHandler):
def handle(self):
sender = self.getUser(self.request.get('id'),
self.request.get('password'))
if not sender:
return
#See if data is in memcache.. if so return it. Each user has it's
own memcache entry based on user email.
#What's stored in memcache is just a return string of all the games
data = memcache.get("gameList-"+sender.email)
if data is not None:
self.response.out.write(data)
#logging.info("Found memcache: %s", str(sender.email))
return
#Get the last 100 where I am the sender
query = db.Query(SkyWordsGame)
query.filter('sender = ', sender.email).filter('senderHideGame = ',
False)
senderGames = query.fetch(100)
#Get the last 100 where I am the recipient
query = db.Query(SkyWordsGame)
query.filter('recipient = ', sender.email).filter('recipientHideGame
= ', False)
recipientGames = query.fetch(100)
#All Games
games = recipientGames + senderGames
#Sort Games
games.sort(key=lambda x: x.lastUpdate, reverse=True)
e = ElementTree.Element("ok")
userRecordDict = {}
actualLength = 0
for game in games:
#Collect info about each game and shove into the ElementTree
memcache.add("gameList-"+sender.email, ElementTree.tostring(e))
self.response.out.write(ElementTree.tostring(e))
I have other methods where I update a game, resign a game, etc.. anything
that would effect the validity of the cache. For any of those methods I
invalidate the cache so it's regenerated the next time the query the game
list. I have no time limit on my cache as I should know when it's going to
get invalid and can strip it then
memcache.delete("gameList-"+sender.email)
I suppose I'm not seeing a big gain if the data is often invalid and keeps
getting deleted.. I almost feel like I'm seeing just as heavy if not heavier
cpu usage. Only explanation I have for that is if the cache is often
invalidated and regenerated and the memcache.add is just adding to my cpu
usage. So the overhead of the .add is outweighing how much I'm using the
cache. Sort of hard to believe but maybe. Any thoughts ?
The other angle I have is to make a new list attribute on each user's record
and list every game they are a part of there.. so I don't have to do the big
queries.. that's going to be a bit more work so I went for this angle first.
Thanks
Daniel
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