Introduction to the Debugging Tools

Ad-hoc debugging, is about guessing the general area of the code base where the source of the problem might be and then tracing the code line by line. Using debugging tools may speedup and safe time/efforts for developers while debugging.

Here we describe common tools for debugging.

Debugging Tools for Windows:

Usage scenarios: Collection of debuggers and tools.

Download: www.microsoft.com/whdc/devtools/debugging/default.mspx

There are three user mode debuggers available in the Debugging Tools for Windows package—NTSD, CDB, and WinDbg—and one kernel mode debugger (kd). Although these debuggers are three separate tools, it is important to understand that they all rely on the same core debugger engine. The most significant difference between the debuggers is that WinDbg has a graphical user interface (GUI) component, making it easier to work with when doing source level debugging.In contrast, NTSD and CDB are purely console-based debuggers

SOS:

Usage scenarios: General debugging extension for .NET applications

Download: it’s already part of .NET SDK

SOS is a debugger extension that can be used to debug .NET applications using the native debugger. It provides a truly amazing set of commands that enables developers to delve deep into the CLR and help troubleshoot pesky application bugs. Among other things, there are commands that enable you to see the finalization queues, managed heaps, managed threads, setting managed code breakpoints, seeing exceptions, and much more.

Because SOS provides an abstracted view into the internals of the CLR, it’s important to note that when debugging using the SOS debugger extension; care must be taken to use the correct version of SOS. Each of the .NET versions ship with its corresponding version of SOS and can be found in the following location:

%windir%\microsoft.net\<architecture>\<version>\sos.dll

Architecture can be either Framework (for 32-bit) or Framework64 (for64-bit), and the version represents the version of the .NET framework you are targeting. Before the SOS debugger extension can be used, it must be loaded into the debugger by using the .load command. The following listing illustrates the loading process when running notepad.exe under the debugger.

Contrary to what you might believe, the SOS debugger extension is not named after the distress signal. When the .NET framework was in its 1.0 stage, the Microsoft development team used a debugger extension called STRIKE to figure out complex problems in .NET code. As the .NET framework matured, so did the debugger extension, and it became known as Son of Strike (SOS).

SOSEX:

Usage scenarios: General debugging extension for .NET applications

Download: www.stevestechspot.com/downloads/sosex_32.zip or www.stevestechspot.com/downloads/sosex_64.zip

SOSEX is another debugger extension targeted at the native debuggers and managed code debugging. It was developed by Steve Johnson and is available as a free download. SOSEX, not surprisingly, stands for SOS Extended. SOSEX adds a set of powerfull debugging commands to your arsenal. Examples of such commands include deadlock detection, generational garbage collection commands, and more powerful breakpoint commands.

CLR Profiler:

Usage scenarios: Memory Allocation Profiler

Download: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=be2d842b-fdce-4600-8d32-a3cf74fda5e1

The CLR Profiler is an invaluable tool when it comes to troubleshooting memory related issues in .NET applications. It provides features such as:

  • Heap statistics (including allocation graphs)
  • Garbage collection statistics
  • Garbage Collector Handle Statistics (including allocation graphs)
  • Garbage Collection Generation Sizes
  • Profiling Statistics

Clicking the Start Application button brings up a dialog where you can choose the application you want to profile. After an application and profiling action has been chosen, the CLR Profiler launches the application and starts collecting data. The CLR Profiler offers a number of different statistical views of the data collected. Below is a screen shot from the application:

The data collected is output to a log file that is by default located in %windir%\Temp. The log filename takes the form:

Pipe_<pid>.log

Where <pid> is the process identifier of the process being profiled. The CLR Profiler can also be started and controlled via the command line.

Performance Counters:

Performance counters are an important part of the troubleshooting process. During the .NET framework installation process, a collection of performance counters is installed. These performance counters represent a goldmine of information when analyzing .NET application behavior. To view the performance counters, the Windows Performance Monitor can be used. Table below lists all the performance counter categories that are part of the .NET runtime.

Reflector for .NET:

Usage scenarios: .NET assembly analyzer and assembler.

Download: http://www.reflector.net/

Reflector for .NET is a .NET assembly explorer tool that includes a powerful disassembler that can reproduce the code from the MSIL (Microsoft Intermediate Language) to a higher level language of choice. The language choices are C#, VisualBasic, Delphi, Managed C++, and Chrome. Additionally, it includes an extensibility model in the form of an add-in API. There are many add-INS available ranging from a code review add-in to a code metrics add-in. Figure 1-4 shows an example of analyzing the Reflector.exe binary itself using Reflector for .NET.

PowerDbg:

Usage scenarios: Debugger tool.

Download: www.codeplex.com/powerdbg

PowerDbg is a library developed by Roberto Farah that allows you to control the native debuggers via Powershell (requires 1.0). It is a super useful tool when you want to control the execution of the debuggers using the command line. The PowerDbgscript returns information to the user in a neat and easily digestible fashion. The greatthing about PowerDbg is that it is easily extensible and enables calling and formattingyour favorite commands (or a set of commands in common debug scenarios).

Managed Debugging Assistants:

Usage scenarios: General CLR Debugging

Download: Part of CLR

Managed Debugging Assistants (MDAs) is not a standalone tool per se; rather, it is a component of the CLR that provides invaluable information when running and debugging .NET applications. If you are familiar with Application Verifier for native code, MDAs serve a very similar purpose. Through elaborate instrumentation of the runtime, common programming mistakes can be identified at runtime and subsequently fixed prior to shipping the application. Find in this link number of available troubleshoot problems within that category.

To utilize MDAs, they must first be enabled (prior to starting the process being debugged). The way to enable theMDAs is via the registry. More specifically, you need to add the following value under the registry key (the value is string type):

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\MDA=”1″

By setting the preceding registry value, you have notified the CLR that MDAs should be utilized. Before you can actually make use of them though, you need to enable specific MDAs on a per application basis. The process of enabling MDAs is done via a configuration file that must be named according to the rule

<appname>.exe.dma.config

where appname is the name of the application that you want to enable MDAs for.The configuration file itself contains all the MDAs that you want enabled.

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