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Moaid HathotSoftware Consultanthttp://moaid.codes

How to become a debugging Jedi

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• Software engineer, consultant and code Jedi• Developing Software professionally since 2013• Software Craftsmanship advocate• Clean Coder

@MoaidHathotmoaidh@codevalue.nethttp://www.moaid.codes

About Me

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About CodeValue

A leading software company• ~180 employees: more than 120 technology experts

• Provides high quality software development solutions• Turn-Key projects• Software development and consultation• Tailor-made courses and training

• Fields of expertise include:• Desktop & LOB applications• Cloud Computing• Advanced Mobile & Web Technologies• User Experience (UX) & User Interface (UI)• Application Lifecycle Management (ALM) and DevOps• Embedded & IoT

Agenda

IntroductionBreakpointsDebugging attributesDebugging multithreaded codeToolsPost-mortem debugging

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The Original Bug Report

• “Debugging is the process of finding and resolving bugs or defects that prevent correct operation of computer software or a system”

• The terms "bug" and "debugging" are popularly attributed to Admiral Grace Hopper in the 1940s

• However the term is much older• Thomas Edison wrote the following words in a letter to an associate in 1878:

• “It has been just so in all of my inventions. The first step is an intuition, and comes with a burst, then difficulties arise — this thing gives out and [it is] then that "Bugs" — as such little faults and difficulties are called — show themselves and months of intense watching, study and labor are requisite before commercial success or failure is certainly reached”

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The Original Bug Report

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Squandered time

Every minute spent in the debugger is a minute squandered.

Period.

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Debugging is a time-travel

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The Aha Moment• The two endpoints of debugging

1. What the heck.

2. Aha!

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Know your tools

Know your tools

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Know your tools

Know your tools

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Controlling The Debugger• There are 10 types of (human) debuggers:

• The “I am too tired to think, let the debugger lead and control” type

• The “everything is under control” type

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Rubber ducking

rubber duck debugging or rubber ducking is a method of debugging code

The name is a reference to a story in the book The Pragmatic Programmer in which a programmer would carry around a rubber duck and debug their code by forcing themselves to explain it, line-by-line, to the duck

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Rubber ducking

rubber duck debugging or rubber ducking is a method of debugging code

The name is a reference to a story in the book The Pragmatic Programmer in which a programmer would carry around a rubber duck and debug their code by forcing themselves to explain it, line-by-line, to the duck

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Breakpoints

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Conditional Breakpoints

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Filters

Tracepoints (VS)

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Tracepoints (VS)

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Method Breakpoints

Ctrl + BIf you type a method name (without class name)

VS select all that matches

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Conditional Breakpoint’s drawbacks

What are the drawbacks of Conditional Breakpoints?

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Debugger Anatomy

Wait for debug event

Handle debug event

Continue debug event

Start the debugger or attach to it

Enter main debugger loop

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Debugger Main Loop

1. …2. for(;;) 3. { 4. WaitForDebugEvent(DebugEv, INFINITE); 5. switch (DebugEv->dwDebugEventCode) 6. { 7. case EXCEPTION_DEBUG_EVENT: 8. switch(DebugEv->u.Exception.ExceptionRecord.9. ExceptionCode)10. { 11. case EXCEPTION_ACCESS_VIOLATION: 12. case …13. }

Source: https://msdn.microsoft.com/en-us/library/windows/desktop/ms681675(v=vs.85).aspx

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Debugger Main Loop

Source: https://msdn.microsoft.com/en-us/library/windows/desktop/ms681675(v=vs.85).aspx

1. break;2. case CREATE_THREAD_DEBUG_EVENT: 3. dwContinueStatus = 4. OnCreateThreadDebugEvent(DebugEv);5. break;6. …7. } 8. // Resume executing the thread that reported the9. debugging event. 10. ContinueDebugEvent(DebugEv->dwProcessId, 11. DebugEv->dwThreadId, 12. dwContinueStatus);13. }}

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Debugger break

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Debugger break

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Conditional Attribute

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Object ID’s

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Lambda Evaluation in Immediate & Watch Windows

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Debugging Attributes

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Debugger Display Attribute

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Debugger Display Attribute

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Debugger Display Attribute

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Debugger Type Proxy Attribute

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Debugger Browsable Attribute

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Debugger Visualizer

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Debugger Visualizer

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Multithreading

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Staying on the same thread (freezing other threads)

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Finding Tasks Deadlocks

Debug –> windows –> Tasks

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Parallel Task & Parallel Stacks

View the logical call, the logical call stack and the task/thread state

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Parallel Watch - View local variable in each thread’s context

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Concurrent Visualizer

https://marketplace.visualstudio.com/items?itemName=VisualStudioProductTeam.ConcurrencyVisualizerforVisualStudio2015

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Concurrent Visualizer

https://marketplace.visualstudio.com/items?itemName=VisualStudioProductTeam.ConcurrencyVisualizerforVisualStudio2015

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OzCode

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LINQ Debugging

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Predicting the future

Predict

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Custom Expressions

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Show All Instances

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Tracepoints (OzCode)

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Conditional Breakpoints (OzCode)

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invoice.Id 915486 intinvoice.Id 915486 int

OzCode Comapre

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Export

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Give it a try

https://github.com/oz-code/OzCodeDemo

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System Internals

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Where to download

Browser: http://Live.sysinternals.comShared folder: \\live.sysinternals.com\tools

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Process Explorer

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Process Monitor

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Post-Mortem Debugging

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Dump Files

• A minidump is a snapshot of a process– May be created at any time, not just when a process crashes

• Minidump types– Kernel minidumps (not relevant for this course)– Basic (usually enough for native processes)– Full (required to get useful info for managed processes)

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Dump Creation

• Minidump creation– WinDbg– On Vista, 2008 and up can use Task Manager– ADPlus– ProcDump

• Opening Dump files– WinDbg– Visual Studio 2012/2013

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Automatic Dump Creation

To enable it, set the reg key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps\<appName>

DumpFolder – Location for the output dumpsDumpCount – Maximum amount of dumps in the folderDumpType

1 – Mini Dump2 – Full Dump0 – Custom Dump

CustomDumpFlags – if DumpType is 0, set the dump options

Debugging using the Dump (1)

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Debugging using the Dump (2)

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Generating Symbol Tables

1. Open DotPeek2. Add the required assembly 3. Press start Symbol server4. In VS add new symbol source

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Debugging is Hard

Debugging is HARD.Even the Pros get befuddled

sometimesUse the right tools to decrease your Time-to-Aha factor

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Kahoot it

Use your browser to visit:https://kahoot.it

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Presenter contact detailst: @MoaidHathote: moaidh@codevalue.netb: http://www.moaid.codesw: www.codevalue.net

Free 3 months of OzCodehttp://tinyurl.com/jpn4y96