Kathleen Dollard - CodeRapid
@kathleendollard
kathleendollard
[email protected]
Blog: http://blogs.msmvps.com/kathleen
http://www.pluralsight.com/author/kathleen -dollard
Better Code,
Better Debugging
Development
Debugging
Production
Legacy
Development
Debugging
Production
Legacy
Development
Debugging
Production
Legacy
o How
to approach bug free code
o How
to debug in tools
o How
to debug production code
o How
to approach bug free code
o How
to debug in tools
o How
to debug production code
o Consistency
◦
◦
◦
◦
Method length
Variable usage
Naming
Spelling
o Got
FxCop?
Visual Studio 2015
Analyzers
o NuGet
delivered
◦ Attached to project
◦ Runs in Visual Studio
◦ Runs in all builds
o Write them!
◦ Or tweak them
◦ Upcoming course on
Pluralsight.com
Summary: Visual Studio 2015 Analyzers
Life With Analyzers
Life Without Analyzers
o How
to approach bug free code
o How
to debug in tools
o How
to debug production code
o How
to approach bug free code
o How
to debug in tools
o How
to debug production code
A Debugging Strategy
Scientific Method
Repro, think,
write test
Something Happens
No
Can you repro in
Visual Studio?
Yes
Create several
hypotheses
Select one
to disprove
Outside
production?
Test
Evaluate
We Work Differently During Development
Development
• During development, you focus
on events from your application
• You need quick access
• Solve bugs every hour
• Repeating many times expected
Production
• During production, interaction with
other things matter
• You have relatively more time and
stress
• Solve bugs every week? Month?
• Repeating problems in production
should be avoided
Visual Studio 2015
o
Debugging
◦ Breakpoint Peek
◦ Watch
◦ Undo Breakpoint delete
o How
to approach bug free code
o How
to debug in tools
o How
to debug production code
o How
to approach bug free code
o How
to debug in tools
o How
to debug production code
Production Bugs
Logger.Log.OpenFile(...)
Your Logging
Framework
Semantic Log
Abstraction
Your Logging
Framework
Production Code
System…Trace.Write(...)
Production Code
Abstraction Over Your Logging Framework
Semantic Logging
private void FireEvent2_Click(object sender, RoutedEventArgs e)
{
Logger.Log.Message("Test message");
}
private void KeyEvent2_Click(object sender, RoutedEventArgs e)
{
Logger.Log.AccessByPrimaryKey(GetPrimaryKey(), "Customer");
}
o
Strongly typed
o
IntelliSense driven
o
Details like keywords and level defined/changed at central point
o
Aids code readability
Things that make debugging hard
o Desktop
◦
◦
◦
◦
Rare
Distance (can’t sit down and watch)
Watching doesn’t help
Registry corruption/error
◦ Machine dependent issues
o Server
◦
◦
◦
◦
◦
Same issues as desktop plus
Inter-process issues
Higher pressure on threads and memory
Authorization issues
Not being an admin
o Hookup
Visual Studio
remote debugging?
o Run
Visual Studio on your
server to debug?
o Tracing records
o Outside
the path through your app
forces affect your app
◦ .NET
◦ Operating system
◦ Service/web calls
◦ Many others
o
ETW integrates view of your application
with outside factors - holistic
Old-Style Tracing
o You
create the entire picture
o Tools
roughly give you a crayon to draw with
o Technique
◦ Trace.WriteXxxx
◦ TraceSource
◦ Third-party such as Log4Net
o In-process
recording devastates scalability
New-Style Tracing
o Out-of-proc
or off-thread very quickly
o Vast amount
o Your
of data already available
app drops ‘orienteering’ locations like GPS points
o EventSource
and Semantic Logging Application Block (SLAB)
On and off,
filtering
ETW Design
ETW Session
ETW Session
ETW
Controller
Create
trace entry
ETW Session
ETW Session
ETW Provider
ETW Sessions – managed by the operating system
ETW
Session
Observe,
access
trace info
ETW
Session
ETW Session
ETW Session
ETW
Consumer
ETW
Session
ETW Design Summary
o
ETW is composed of
◦
◦
◦
◦
o
Core (sessions)
Controllers
Providers
Consumers
ETW does most of the work outside your process
◦ Particularly important for resources like writing files
o
ETW is blazingly fast
◦ It’s in the operating system
◦ It creates binary files or streams
o
Manifests explain how to interpret binary files
◦ Contain provider IDs (use strings), event IDs (integers 0, 1…), and payload def
◦ Can be registered on the machine
◦ Can be in-line in a message
Overly Simple (bad) EventSource
Default Id is
“SimpleEventSource”
namespace EventDefinitions
{ public class SimpleEventSource : EventSource
{static public SimpleEventSource Log
= new SimpleEventSource();
public void Message(string Message)
{ WriteEvent(1, Message); }
public void AccessByPrimaryKey(
int PrimaryKey, string TableName)
{ WriteEvent(2, PrimaryKey, TableName); }
}
}
o Please
define a few things
These must
match the
order of
logging
methods
in the file
Parameters/args
must match
“Normal” (good) EventSource
[EventSource(Name = "KadGen-EtwSamples-Normal")]
public class NormalEventSource : EventSource
{
static public NormalEventSource Log
= new NormalEventSource();
[Event(1)]
public void Message(string Message)
{ WriteEvent(1, Message); }
[Event(2)]
public void AccessByPrimaryKey(
int PrimaryKey, string TableName)
{ WriteEvent(2, PrimaryKey, TableName); }
o Please define a few things
}
Semantic Logging Application Block
SLAB
o Uses
EventSource (.NET 4.5+)
◦ No other dependencies
o Fantastic documentation, including semantic logging concepts
o Out-of-proc
o Use
provides consumers you’re familiar with
in-proc if it’s the best your team can do now
o Sadly, lag behind
EventSource version
Profiling
Profiling
o Do
you use a profiling tool?
◦ Do you know how to use one?
o Do
you believe you will never have a performance problem?
◦ Are you planning on hiring an expert and have budget in place?
Visual Studio 2015
o
Profiling
Visual Studio 2015
o
Profiling
◦ PerfTips
Profiling
o Do
you use a profiling tool?
◦ Do you have one you know how to use?
o Do
you believe you will never have a performance problem?
◦ Are you planning on hiring an expert and have budget in place?
o Pragmatic plan
#1 (imperfect base plan)
◦ PerfTips to find candidate issues
◦ Start/Stop tracing to confirm
◦ Manually explore that <150 lines of code
o Pragmatic plan
#2 (issue seems unpredictable, broad, nonsensical)
◦ Look for allocation issues
o Pragmatic plan
#3: Call an expert
o Pragmatic plan
#4: Live with it
Development
Debugging
Production
Legacy
Development
Debugging
Production
Legacy
Debugging
o Scientific method
◦ Record ideas
◦ Try to disprove one
◦ Reconsider ideas
Development
Production
Legacy
o Learn
Visual Studio tools
o Provide
logging
◦ Out of proc and semantic
o Refactor
◦ Then fix
o
[email protected]
o
My blog: http://msmvps.com/blogs/kathleen
o
@kathleendollard on Twitter
o
www.WintellectNow.com, Free Series
o
Pluralsight, Kathleen Dollard
◦
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Event Tracing for Windows (ETW) in .NET, http://bit.ly/1iZeoyZ
.NET Puzzles, http://bit.ly/19z2JaD
What’s New in .NET 4.5, http://bit.ly/YTb962 Module 3 is ETW
Visual Studio 2015 Analyzers, upcoming
o
Vance Morrison’s blog: http://blogs.msdn.com/b/vancem/
o
SLAB https://github.com/mspnp/semantic-logging