Raymond Chen

Raymond has been involved in the evolution of Windows for more than 30 years. In 2003, he began a Web site known as The Old New Thing which has grown in popularity far beyond his wildest imagination, a development which still gives him the heebie-jeebies. The Web site spawned a book, coincidentally also titled The Old New Thing (Addison Wesley 2007). He occasionally appears on the Windows Dev Docs Twitter account to tell stories which convey no useful information.

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When is a window visible yet not visible?

May 20th, 2005
Today, a quick puzzler. Consider the following code fragment: We just showed the window, certainly it is visible, right? Yet the assertion can fire (even in the absence of multi-threading). Why? Answer below - stop reading if you want to try to solve it yourself. Take a look at the function. If the specified ...

Loading the dictionary, part 6: Taking advantage of our memory allocation pattern

May 19th, 2005
Designing a memory allocator that exploits our memory allocation pattern.

Loading the dictionary, part 5: Avoiding string copying

May 18th, 2005
Looking at the profile for our program so far, 35% of the CPU time is spent copying strings around. Let's see if we can improve that. The best way to speed up copying strings is not to copy them in the first place. Using a in our structure forces the class to copy the string data, when all we really need to copy is the pointer and size ...

You can't escape those AOL CDs

May 17th, 2005
One of my colleagues was unpacking one of those $30,000 quad-processor more-memory-than-you-know-what-to-do-with super-server computers. The kind that require their own electrical substation. And it came with an AOL CD. It's like buying a Lexus and finding a 35-cents-off coupon in the glove compartment. Apparently, one of the questions AOL ...

Loading the dictionary, part 4: Character conversion redux

May 16th, 2005
Getting rid of was a big help, but 480ms is still not quite peppy enough. You need to respond to user actions within a tenth of a second for thing to seem responsive. Profiling the latest endeavor reveals that 40% of our CPU time is spent in . Some debugging reveals that ultimately calls but uses it to convert only one or two ...

Loading the dictionary, part 3: Breaking the text into lines

May 13th, 2005
Even after moving the character conversion out of the function, profiling reveals that is still taking nearly 50% of our CPU. The fastest code is code that isn't there, so let's get rid of altogether. Oh wait, we still need to break the file into lines. But maybe we can break the file into lines faster than did. This very simple class...

The Microsoft corporate network: 1.7 times worse than hell

May 12th, 2005
Today I'm going to tell a story from 1996. Why? Because I can. One of the tests performed by Windows Hardware Quality Labs (WHQL) was the NCT packet stress test which had the nickname "Hell". The purpose of the test was to flood a network card with an insane number of packets, in order to see how it handled extreme conditions. It uncovered ...

Loading the dictionary, part 2: Character conversion

May 11th, 2005
When you want to optimize a program, you first need to know where the time is being spent. There's no point optimizing a function that isn't actually responsible for your poor performance. For example, if a particular function is responsible for 2% of your CPU time, then even if you optimized it down to infinite speed, your program would...

Loading the dictionary, part 1: Starting point

May 10th, 2005
The first thing we'll need to do in our little dictionary program is to load the dictionary into memory. The format of the dictionary file is as a plain text file, each line of which is of the form Since it was the Big5 dictionary we downloaded, the Chinese characters are in Big5 format, known to Windows as code page 950. Our program will...

Developing a Chinese/English dictionary: Introduction

May 9th, 2005
The other day, one of my colleagues mentioned that his English name "Ben" means "stupid" in Chinese: 笨/bèn/ㄅㄣˋ. (His wife is Chinese; that's why he knows this in the first place.) Knowing that the Chinese language is rich in homophones, I fired up my Chinese/English dictionary program to see if we could find ...