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Oct 20, 2005
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Quick and dirty buzzword bingo cards in Excel

Raymond Chen

Jensen Harris's brief example of using Excel's random number generator reminded me that I had need for the random number generator recently myself: Generating buzzword bingo cards. At the Battlestar Galactica party, our hosts needed to create some Battlestar Galactica-themed buzzword bingo cards and asked me to help out. Here's how I did it: ...

Code
Oct 14, 2005
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Thread affinity of user interface objects, part 5: Object clean-up

Raymond Chen

The window manager and GDI objects as a general rule will automatically destroy objects created by a process when that process terminates. (The window manager also destroys windows when their owner threads exit.) Note, however, that this is a safety net and not an excuse for you to leak resources in your own program with the attitude of "Oh, it do...

Code
Oct 13, 2005
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Thread affinity of user interface objects, part 4: GDI objects and other notes on affinity

Raymond Chen

GDI objects are much simpler. As a general rule, they all have process affinity: They can be used by any thread in the process that created them. If you use a GDI object from multiple threads, it is your responsibility to coordinate the object's use. Note that the window manager and GDI as a general rule keep their respective objects thread-safe....

Code
Oct 12, 2005
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Thread affinity of user interface objects, part 3: Menus, icons, cursors, and accelerator tables

Raymond Chen

The remaining user interface objects in common use are menus, icons, cursors, and accelerator tables. Menus do not have thread affinity. Any thread can use a menu. However, if two threads use a menu, it is the responsibility of those threads to coordinate among themselves how that menu will be used, so that one thread doesn't modify a menu while ...

Code
Oct 11, 2005
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Thread affinity of user interface objects, part 2: Device contexts

Raymond Chen

Last time, we discussed briefly the thread affinity rules that govern window handles. Device contexts (DCs) also have a certain degree of thread affinity. The thread that calls functions such as must also be the one that calls , but as with window handles, during the lifetime of the DC, any thread can use it. If you choose to use a DC in a mul...

Code
Oct 10, 2005
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Thread affinity of user interface objects, part 1: Window handles

Raymond Chen

Different objects have different thread affinity rules, but the underlying principles come from 16-bit Windows. The most important user interface element is of course the window. Window objects have thread affinity. The thread that creates a window is the one with which the window has an inseparable relationship. Informally, one says that the th...

Code
Oct 7, 2005
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On the dangers of sharing your apartment

Raymond Chen

My colleague Marc Miller wrote up a brief essay on the subject of dealing with a neutral apartment that has been injected into your single-threaded apartment: COMmunism: Sharing your Apartment. Highly recommended.

Code
Oct 6, 2005
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The unfortunate interaction between LOAD_LIBRARY_AS_DATAFILE and DialogBox

Raymond Chen

Some people have noticed that if you load a DLL with the flag, you sometimes get strange behavior if you then pass that to a dialog box function. The problem here is that since the bottom 16 bits of a proper are always zero, different components have "borrowed" those bits for different purposes. The kernel uses the bottom bit to distinguish mo...

CodeHistory
Oct 4, 2005
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Consequences of the scheduling algorithm: Sleeping doesn’t always help

Raymond Chen

More often I see the reverse of the "Low priority threads can run even when higher priority threads are running" problem. Namely, people who think that is a clean way to yield CPU. For example, they might have run out of things to do and merely wish to wait for another thread to produce some work. Recall that the scheduler looks for the highest...

Code
Oct 3, 2005
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Consequences of the scheduling algorithm: Low priority threads can run even when higher priority threads are running

Raymond Chen

Just because you have a thread running at a higher priority level doesn't mean that no threads of lower priority will ever run. Occasionally, I see people write multi-threaded code and put one thread's priority higher than the other, assuming that this will prevent the lower-priority thread from interfering with the operation of the higher-prior...

Code