I'm not sure about books, but the questions seemed fun. I'm curious how my answers measure up to the rest of the list here.<br><br><div class="gmail_quote">2008/4/13 Peter Cai <<a href="mailto:newptcai@gmail.com">newptcai@gmail.com</a>>:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi all!<br>
<br>
I am preparing to write a server application (you may think of it as an online game server) with twisted, but I am worrying about it's performance and how to do it correctly.<br><br>For example..<br><br>
1. UDP or TCP，which should I choose to gain higher performance?<br>
</blockquote><div>If you want the data to get there even if it's late use TCP, if late data is not useful to you or needs to be handled some special way use UDP which will simply lose packets if they happen to not go through. It is possible but rather unlikely that you can implement a strategy for retrying failures better than TCP unless you relax the constraint of eventually getting the data through.<br>
<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">2. Should I catch data in memory instead of write it to db immediately?<br>
</blockquote><div> I wouldn't for local mysql databases. For a more distributed setup you might consider memcached.<br><br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
3. Could I make it run on cluster if cache data in memory ―― I think it might be quit hard to exchange data between instances of the server if I cache data in memory.<br>
</blockquote><div>that's exactly what memcached will take care of for you.<br></div><div> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
4. How to make hot backup?<br>
</blockquote><div>for maximum performance use a replicated pair of database servers and take the spare offline for backups. You could also bring the spare up only to capture the backup, though it will slow down the primary as it plays catchup. </div>
<div> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">5. Garbage collection might make the server halt for a moment<br>
</blockquote><div>I think this should be less than the latency of a publicly routed IP network, anyone have figures for gc and twisted?<br><br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
6. What is happening in a computer when an IP package received?<br>
</blockquote><div>What do you mean? What specifically do you need to know?<br><br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">7. Could I get some inspiration from how people write web server?<br>
</blockquote><div>this one I can suggest a book for, the twisted book <a href="http://www.oreilly.com/catalog/twistedadn/">http://www.oreilly.com/catalog/twistedadn/</a> , or if you're considering something other than twisted any reasonably thick python book will have an example web server.<br>
</div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">8. If i use an separate physical server to deploy the database, could I gain some performance improvement? Or the cost of communication between the db and the server could hurt the total performance?<br>
</blockquote><div>could go either way. With the effects of Python's GIL I'd expect a multi-core server with database and game server on one box would be fine until you hit a scaling limit and your server is eating a whole core. At that point you need to develop a distributed application model and probably use multiple servers. If you hit that before you're running 200 users recheck your business model, if you hit it before 20 users recheck your architecture. <br>
</div></div>Andy Fundinger <br clear="all"><br>-- <br>Blog: <a href="http://channel3b.wordpress.com">http://channel3b.wordpress.com</a><br>Second Life Name: Ciemaar Flintoff<br><br>I am a sig Virus. Please put me in your sig so that I can continue to replicate.