High-Performance Server Architecture

I find that the best thing to do is to identify the large objects in a program, such as data blocks, make sure those get allocated separately as described above so that they don't need to be copied, and not sweat too much about the other stuff.

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The purpose of this document is to share some ideas that I've developed over the years about how to develop a certain kind of application for which the term "server" is only a weak approximation. More accurately, I'll be writing about a broad class of programs that are designed to handle very large numbers of discrete messages or requests per second. Network servers most commonly fit this definition, but not all programs that do are really servers in any sense of the word. For the sake of simplicity, though, and because "High-Performance Request-Handling Programs" is a really lousy title, we'll just say "server" and be done with it. I will not be writing about "mildly parallel" applications, even though multitasking within a single program is now commonplace. The browser you're using to read this probably does some things in parallel, but such low levels of parallelism really don't introduce many interesting challenges. The interesting challenges occur when the request-handling infrastructure itself is the limiting factor on overall performance, so that improving the infrastructure actually improves performance. That's not often the case for a browser running on a gigahertz processor with a gigabyte of memory doing six simultaneous downloads over a DSL line. The focus here is not on applications that sip through a straw but on those that drink from a firehose, on the very edge of hardware capabilities where how you do it really does matter. Some people will inevitably take issue with some of my comments and suggestions, or think they have an even better way. Fine. I'm not trying to be the Voice of God here; these are just methods that I've found to work for me, not only in terms of their effects on performance but also in terms of their effects on the difficulty of debugging or extending code later. Your mileage may vary. If something else works better for you that's great, but be warned that almost everything I suggest here exists as an alternative to somethi

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