Visual Studio Hacks

Debug a Failing Application #42

Chapter 5, Debugging

|

165

HACK

—Ben Von Handorf

HACK

#42

Debug a Failing Application Hack #42

Launch the debugger when an application starts to crash.

Just-in-time debugging, or JIT debugging for short, is the ability to attach to

a running program that has failed by throwing an unhandled exception. For

instance, you might be testing an application, but not running the applica-

tion in the debugger, and the application throws an exception. Without JIT

debugging, you would have to try and reproduce the error after restarting

the application in the debugger. With JIT debugging, you can immediately

attach to the program and investigate the exception.

JIT debugging does not have anything to do with Just-in-

time compilation; the abbreviation may mean the same thing

but represents vastly different things. Just-in-time compila-

tion is the part of the Common Language Runtime that com-

piles intermediate language into machine code “just in time”

for the machine to process it. (Literally when you call a

method, the JIT compiler checks to make sure the code for

that method exists; if it does not, then it is compiled from

the IL [Hack #63].)

Using JIT Debugging

Using JIT debugging is pretty simple. When you are running an application

that throws an unhandled exception, you will see the dialog shown in

Figure 5-30.

The Just-in-Time Debugging dialog offers you a number of different debug- ...