May 2016 | Page 2 of 3 | The Old New Thing

But Australian Telecom loves it!

Raymond ChenMay 17, 2016May 17, 201605/17/16

There are two popular ways of measuring how widespread a problem is: You can look at the number of times the problem occurs, and you can look at the number of users it happens to. Back in the late 1990's, I remember a presentation from a product team on things they learned from their telemetry. One of the most important things gathered from ...

Wow, that article sounds an awful lot like something I would have writt… hey, wait a second

Raymond ChenMay 16, 2016May 16, 201605/16/16

A customer (via their customer liaison) had a question about the meaning of the lock overlay icon. Another colleague responded with a link to a site that contained an explanation. I read the linked article and thought to myself, "Wow, that article sounds an awful lot like something I would have written." The style of the writing is similar ...

Is Metro on fire today?

Raymond ChenMay 13, 2016May 13, 201605/13/16

Two fires in one day in the Washington, DC Metro inspired a single-serving-site: ismetroonfiretoday.com. Answers the question on the tin. Bonus chatter: One of my friends told me that a few jobs ago, the project he worked on had a problem with people checking changes into the project when the tree was supposed to be locked. And by "people", ...

Why am I being told that my message ID is too large?

Raymond ChenMay 13, 2016May 13, 201605/13/16

A customer asked for help with an error message in the message compiler. Our message file goes like this: When we compile it, we get this error: Our understanding is that we defined our message ID as a DWORD (which is an unsigned 32-bit integer), and the value 0x10001 easily fits inside an unsigned 32-bit integer. Is there a command line ...

How come a duplicated token doesn’t behave identically to the original?

Raymond ChenMay 12, 2016May 12, 201605/12/16

A customer was experimenting with tokens and discovered that things fall apart when they have a thread impersonate itself. Shouldn't that have no effect? Here's what they discovered. Error checking and cleanup have been elided for expository purposes. The DuplicateToken function says that the new token duplicates the original, but it ...

What’s the difference between duplicating the handle to a token and duplicating a token?

Raymond ChenMay 11, 2016May 11, 201605/11/16

If you have a token, there are two ways to get another handle to it. One is to use DuplicateHandle; the other is to use DuplicateToken (or DuplicateTokenEx). What's the difference? Duplicating the handle with DuplicateHandle results in a new handle that refers to the same token as the original handle. On the other ...

How can my CPU be running faster than the maximum speed?

Raymond ChenMay 10, 2016May 10, 201605/10/16

A customer observed that according to Task Manager, their CPU was running faster than the maximum speed. How is that even possible? The processor's maximum speed is 2.50GHz, but it's running at 2.90GHz? I know that athletes give 110% effort, but this processor is giving 116%! This is a feature of Intel Turbo Boost ...

Taking shortcuts when following driving instructions doesn’t always pay off

Raymond ChenMay 9, 2016May 9, 201605/9/16

Many years ago, I had to pick up a package from the local UPS distribution center. This was back in the old days, before everybody had a GPS with turn-by-turn navigation. In the uphill-both-ways era, the way you figured out how to get somewhere was to pull out a map printed on paper and plot your strategy unassisted. Armed with my homemade ...

Is it okay to acquire an SRWLOCK recursively? (And why not?)

Raymond ChenMay 6, 2016May 6, 201605/6/16

A customer was using an SRWLOCK to protect access to an object. All functions that use the object acquire the SRWLOCK in shared mode, and the function that destroys the object acquires the SRWLOCK in exclusive mode. This seems correct to us, but we found that when running under the Application Verifier, we receive many errors complaining that...

How can I write an unkillable program, redux

Raymond ChenMay 5, 2016May 5, 201605/5/16

A customer wanted to know how to write an unkillable process. Specifically, they want to write a program that runs continuously in the background, and they don't want the logged-in used (who is not an administrator) to be able to terminate it. They wanted to know if there was a way to hide the program from Task Manager, so the user cannot ...

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