什么比保存服务器系统资源更好

Question

I made a private chat system. So far the chat has 3 jquery ajax post scripts calling to the server in a loop for new data.

1. Message window between current user and target user (The ajax gets the timestamp of the last message on the db and compares it to the last message timestamp that was displayed. Get all messages > than last message timestamp and display it on message window. ajax loops every 5 seconds after last return.)

2. Whos online checker (Checks db for whos online. ajax loops every 30 seconds after last return)

3. Who messaged current user (Check and Get users who are not the current target user on the message window and has messaged the current user. ajax loops every 15 seconds after last return)

So far the above 3 are the only ajax loops I have and I am still double checking my code for areas where I can trim it down.

My question is. Would it be better in conserving server system resources if I group together the above 3 ajax post to create 1 ajax post and loop it every 5/8 seconds. Or should I leave it as?

I ask this because I got a warning from my hosting before that I was consuming too much of their server's system resources (due to a very stupid experiment). If I mess up again their gonna cut my hosting so I do hope you guys understand why I ask this kind of question.

Extra details: I use jquery ajax to talk to a php script that gets the data from a mysql db. The loop for the requests are done client side.

Answer 1

Websockets are tricky. So if you decide to go with ajax there are a couple of factors to consider:

1. The frequence. Efficient systems usually use a sort of tick system. In your case a tick would be 5 seconds as all your time lines can be tacted into a 5 second tact. And yes of course you group all transmission needs of a tick into 1 transmission.
2. The data quantity. Try to not send more than 1KB of Bytes per tick. Eg. use sparse formats like csv over eg. XML. Set hard entry limits. Compress. Things like that. Network traffic is packaged - so sending 1025 Bytes causes allocation of 2KB resources.
3. Act on user's inactivity somehow. Eg. do not use up each tick for the "Message window between current user and target user" if the user is inactive for more than a minute. Sort-of-session timeout of 20 minutes or so...
4. The computation. Make the server side tick response QUICK and small. Consider to use memory tables or mem chaches for the tick handling and then have a ten minutes or so agent that stores to persistence what is needed to go there. Try to avoid complex fat operations (like eg. >3 db round trips) in the tick response.
5. The hoster. That was also said in other comment. A quick additional hint: You could ask if you are allowed to implement that thing before you sign the contract, if you are able to change the contract. Sometimes there are things like video and instant messaging mentioned in the general terms of service.

There are probably more things.. But these come to my mind immediately...

In general maybe you should also check out https://developers.google.com/speed/docs/best-practices/rtt