Friday 16 May 2014

Are Debuggers Crutches?

Debuggers have become powerful tools, but like a drug have we become too dependent on them? Since poor developers spend 25 times more time in the debugger there is a likelihood that people are zoning out in the debugger instead of using other methods.

Defects are common, but they are not not necessary.  They find their way into code because:
Defect correction is only possible if you understand the code pathways, debuggers are not the best way to do this

Debuggers are commonly used by developer's to understand a problem, but just because they are common does not make them the best way to find defects.  I'm not advocating a return to "the good old days" but there was a time when we did not have debuggers and we managed to debug programs.

Note: in embedded systems it is very hard to get feedback if you do not use a debugger (or hardware debugger).  This article is not addressed to embedded developers who rarely have an alternative to a debugger.

Avoid Defects

The absolute best way to remove defects is simply not to create them in the first place. You can be skeptical, but things like  the Personal Software Process (PSP) have been used practically to prevent 1 of every 2 defects from getting into your code.  Over thousands of projects:

The Personal Software Process increases productivity by 21% and increases code quality by 31%1

A study conducted by NIST in 2002 reports that software bugs cost the U.S. economy $59.5 billion annually. This huge waste could be cut in half if all developers focused on not creating defects in the first place.

Not only does the PSP focus on code planning, it also makes developers aware of how many defects they actually create.  Here are two graphs that show the same group of developers and their defect injection rates before and after PSP training.2

Before PSP training After PSP training

Finding Defects

Using a debugger to understand the source of a defect is definitely one way.  But if it is the best way then why do poor developers spend 25 times more time in the debugger than a a good developer? (see No Experience Required!)

Poor developers spend a week in the debugger for every 2 hours that good developer does

No one is saying that debuggers do not have their uses.  However, a debugger is a tool and is only as good as the person using it.  Focus on tools obscures lack of skill (see Agile Tools do NOT make you Agile)

If you are only using a debugger to understand defects then you will be able to remove a maximum of about 85% of all defects, i.e. 1 in 7 defects will always be present in your code.

Would it surprise you to learn that their are organizations that achieve 97% defect removal3?  Software inspections take the approach of looking for all defects in code and getting rid of them. Learn more about software inspections and why they work here:

Software inspections increase productivity by 21% and increases code quality by 31% 

Even better, people trained in software inspections tend to inject fewer defects into code. When you become adept at parsing code for defects then you become much more aware of how defects get into code in the first place.

But interestingly enough, not only will developers inject fewer defects into code and achieve defect removal rates of up to 97%, in addition:

Every hour spent in code inspections reduces formal QA by 4 hours


As stated above, there are times where a skilled professional will use a debugger correctly.  However, if you are truly interested in being a software professional then:
  • You will learn how to plan and think through code before using the keyboard
  • You will learn and execute software inspections
  • You will learn techniques like PSP which lead to you injecting fewer defects into the code
You are using a debugger as a crutch if it is your primary tool to reduce and remove defects

Related Articles

Want to see more sacred cows get tipped? Check out:

Make no mistake, I am the biggest "Loser" of them all.  I believe that I have made every mistake in the book at least once :-)


Monday 5 May 2014

Agile tools do NOT make you Agile

Ask yourself the following questions:
  • Do great golf clubs make you a great golfer?
  • Does a formula one race make you an expert driver?
  • Do great development tools make you an expert developer?
Unless you are delusional, you know that the answer is NO to all these questions.  An expert's performance can be dramatically improved with the right tools, but a beginner will not perform better with a great tool.

No matter how Agile-enabled tools like Version One and JIRA become, using either tool will not make you Agile unless you understand what processes make agile development work.

I recently finished a contract at a large retailer where they use JIRA for an enterprise integration project. It was interesting to hear them use terms like sprint and back log; interesting because there was no regular sprint cycle, and the back log was only the tickets in the JIRA system.  JIRA supports the notion of user stories (epics and stories) yet neither of these were being used correctly.

The problem isn't  JIRA; the problem was that they believed that their process was Agile because JIRA supports agile development.

Being agile is about following the Agile Manifesto.

Agile software development is not informality. Agile development has fewer formal practices than traditional waterfall development and those formal practices need to be adhered to (see Agility is not informality).  Agile development is light weight because it avoids activities that are unnecessary to the production of working code, not because it avoids rigour and formality.

There are implementations of Scrum and XP that WORK and are agile because they implement sound development processes.  However, there are also plenty of organizations that are implementing Scrum and XP incorrectly (see Does Agile Hide Development Sins?)

Agile does not dictate that you have a fixed development CYCLE, but you can definitely succeed with one.  What is required is that you break a project into multiple cycles where you iterate on development.
Agile does not dictate HOW you keep your requirements (back log or stories) but you must have an effective requirements process.  If your requirements process is broken then you will never succeed with agile.

The Agile Manifesto puts the priority on things critical to development:
  • Individuals and interactions
  • Working product
  • Customer collaboration
  • Responding to change
However, agile does not reject things in the right hand column, unless they get in the way of the above factors:
  • Processes and tools
  • Comprehensive documentation
  • Contract negotiation
  • Following a plan
In particular, don't get get caught up in Processes and tools, i.e. Version One and JIRA.  These tools can help you if you understand the core principles of agile development.  If you don't, then these tools will leave you worse off than before.  Unfortunately, the popularity of agile development has every tool maker scrambling to change their product to support agile.

Tools will never extract or synthesize quality requirements and build quality code.  The only way to get to proper understanding of a project is to put priority on individuals and interactions; people and communication are the only way to solve problems -- tools are a secondary concern.

Individuals and interactions OVER processes and tools

Agile development does not dictate a fixed development cycle, but it does require that any cycle must finish with a working product.  The emphasis always has to be production code and that is why periodic demonstrations of working code are essential.

To accomplish this you need to understand your requirements, whether you have a back log or user stories.  There are many times when properly written use cases can be used.  Either way the requirements need to be correct and consistent, they need to be what the customer need, i.e. avoid hiding behind excessive documentation.

Working Product OVER excessive documentation

There is no way to get the requirements correct unless you have a strong working relationship with the customer.  The customer often does not get the initial requirements correct and often development does not understand them.  Focus on customer collaboration is the key to mutual understanding.

This is where most projects fall apart because both parties have a tendency to focus on contract negotiation. Contracts are necessary, but focusing on limiting liability and protecting yourself will not yield a relationship that leads to working software.

 Customer Collaboration OVER contract negotiation

You have to understand that following a plan does not make sense when either requirements or technical uncertainty causes you to change development direction due to the need to respond to change.

It means making reliable estimates up front of all requirements, not just caving into pressure from upper management (see Why Senior Management Declared Deadlines lead to Disaster).  This often means adding time to the projected end of the project when new requirements are discovered or technical challenges force work arounds.  Unfortunately, many projects do not re-adjust the projected end date under these circumstances, which leads to a death march project (see Death March Calculus)

Responding to change OVER following a plan

Agile development is about producing quality software by understanding the principles of the Agile Manifesto.  Agile development is not about deluding yourself simply because you are using a tool that supports agile development.  You can implement a very solid light weight agile solution using only spreadsheets.

Focus on being Agile first, then go find a tool

Other things that are compatible with agile development: