Software Reviews, Walkthroughs, Inspections, and

AuditsBetter to find an error twice than

never to find it at all.

[Freedman/Weinberg 90] Freedman, D.P., G.M. Weinberg, "Handbook of

Walkthroughs, Inspections, and Technical Reviews", Dorset House Publishing Co., Inc., 1990, pp. 89-

161.

Update terminology according

Give references to O’Neil

Why Do We Have Formal Technical Reviews?

1. To err is human.

2. Lots of errors escape the originator more easily than anyone else.

3. Reviews are educational.

Purpose: Provide

• visibility into state of project

• opportunities for personnel (project and non-project) to discuss topics related to project

• intermediate milestones and sense of progress

• assessment of technical adequacy of project

Use the power of a team to …

• Point out needed improvements of a product.

• Confirm the parts in which improvement is not needed or desired.

• Make technical work more uniform and predictable in quality, which makes it more manageable.

Technical review is different from other reviews

• For example, budget and management reviews

• Technical review answers question: will this product do the job it’s supposed to do

• If answer is “no”, then – no schedule is on time, and – no cost is cheap enough.

When?

• Single review that occurs on a particular date• Single review that occurs in response to a

particular condition• Multiple reviews that occur periodically: e.g.,

monthly• Multiple reviews that occur in response to a

particular condition, e.g., code review for subsystem

Benefits

• 10X reduction in errors in products

• 50-80% cost reduction

Why not just pass it around and have reviewers sign off …

Why not just pass it around and have reviewers sign off …

• Comments are too large

• Comments are unread

• Reviewers don’t have to take responsibility for the content.

Requirements

• Team participation

• Documented procedures

• Documented results

Types of Reviews

• Management Review

• Technical Review

• Walkthrough

• Inspection

• Audit

Types of Reviews

• Management Review– Evaluation of project-level plan or project progress

– Monitors status of schedules and compliance to requirements

• Technical Review• Walkthrough• Inspection• Audit

Management Review

• Objectives:– Inform management of project status

– Resolve higher-level issues (management decisions)

– Agree on risk mitigation strategies

• Decisions– Identify corrective actions

– Change resource allocation

– Change project scope

– Change schedule

Types of Reviews

• Management Review

• Technical Review– Focus on specification and design– Determine whether products meet specs

• Walkthrough

• Inspection

• Audit

Scenario for a typical review

• Leader: Welcome. We are here to review X for the purpose of Y.

• Each person is introduced.• The recorder is introduced.• An agenda is presented and the review process

explained.• The list of material in the review packet is stated.• The review begins…

Review

• Agenda set by leader, agreed to by committee

• Review proceeds line-by-line.

• Reviewers bring up issues as they encounter them.

• Issues are added to an Issues List.

• Agenda changes as issues are encountered.

Round Robin Review

• Force every member to participate.

• Each person takes the lead for a section:– paragraph, – line of code, – function, – test case

• Good way to get involvement from team.

Types of Reviews

• Management Review• Technical Review• Walkthrough

– Used to find anomalies and evaluate conformance

– Typically used for source code

– Effective form of education

• Inspection• Audit

Walkthroughs

• Producer guides review• Step by step presentation of product:

– Code, design, report, test cases …• Can cover lots of material• Can have more people attend, less prepared• More work for presenter• May be difficult to control interactions

– Too many interruptions– Always hard to have a producer present

Walkthroughs

• Participant should spend 1 hour preparing for each hour in meeting

• Should be scheduled to be brief

• Should only review completed code or document

• Should require participants to sign report

Types of Reviews

• Management Review

• Technical Review

• Walkthrough

• Inspection– More formal type of walkthrough– Used to identify specific errors or problems

• Audit

Inspections

• Rapid evaluation of material with specific aspect in mind

• Confine attention to one aspect only– Eg assume details are correct, but look for

missing items at a global level– Eg look for occurrences of a particular kind of

bug such as buffer overflow.

• Selection of aspects is key point.

Types of Reviews

• Management Review

• Technical Review

• Walkthrough

• Inspection

• Audit– Independent evaluation of process or product– Ensures that the process is being followed

Review Teams

• Permanent or semi-permanent teams

• IV&V or QA teams

• Get to be very good at reviews

• Need to have some way of reviewing the reviewers.

The team• Leader

– Job: obtain a good review or report why it was not possible• Reflects the quality of the review process, not the quality

of the product• Must be accurate

• Recorder– Provide info for accurate report of review– Short, public notes– Capture essence of each issue– Must ensure group has reached conclusion– Don’t video tape

Tasks of leader

• Monitor preparedness of team members• Set pace• Keep meeting on track• Poll members to reach consensus• Ensure participation• Has right to terminate review if it is unproductive

– Disagreements– Fatal flaws

Consensus

• Decision of the group is equal to the most severe opinion of the group members.

• Be conservative.

• Accept the doubts of the most doubting member.

• No “I told you so, but I got outvoted”.

Reviewers

• Must be qualified to contribute

• Must be unbiased

• Don’t invite management if it causes conflict– The point is to review the project, not the

producers.

Rules for Reviewers

I. Be prepared

II. Evaluate product, not people.

III. Watch your language.

IV. One positive, one negative.

V. Raise issues, don’t resolve them.

VI. Record all issues in public.

VII. Stick to technical issues.

Rules for Reviewers

• If you find something, assume it’s a mistake. These are your peers, not your enemy. Remember people are involved

• Avoid “why did you …” why didn’t you …”say instead “I don’t understand …”

– “Why did you set the upper bound to 10 here?”– “I don’t understand why the upper bound is 10 here.”– seems trivial, but it’s not.

• Do not get bogged down in style issues. For example, if efficiency isn’t an issue, then don’t make it one.

• If it makes things less maintainable, that’s an issue. • If there are standards, then either stick to the

standard, or dispose of the standard.

Number of Reviewers

• Ensure material is covered

• Have enough

• Don’t have too many

• 3-7 is good– Count participants only– 3: ensures material is understood

• Outsiders can be good. Must be unbiased

Time

• At most 2 hours at a time

• Come back again if necessary

• Depends on – Complexity– Size of project– Closeness to completion

Everyone must prepare!

• Review packet• Everything relevant to making correct

judgment: code, specs, test data, results, standards, designs, …

• 80% of failures stem from unprepared teams

Tactics for participation• Devil’s Advocate

– One person makes strongest case against a product– Job is to find fault– Needs to be an actor

• Debugging– Producers leave known bugs in– Quality of review depends on how many found

• Alarms– Time each person’s contribution, cut off

• Stand-up Reviews– Talk as long as you stand on one leg

Report

• Goal: Does the product do the job its supposed to do?– Complete.– Correct.– Dependable as basis for other work– Measurable for purposes of tracking.

• What was reviewed?• Signatures of reviewers.• Leader and recorder.

Notes

• Requires learning: to review and to write

• Need to allocate time

• Not a form of project management– But can provide information for tracking

• Review early and often– But not too often

Need for Reviews

• Reviews help organization deliver quality product– Examine individual parts early in process– Identify problems spanning multiple items or

phases

• Reviews help identify problems early• Reviews help build image of the product

and the vision of the product in the minds of the team members

Cost of Software Reviews• Up-front cost for

– Training– Staff preparation– Review Conduct

• Code review may be 8-15% of total cost of project• Offset by savings: reduced rework later in project

(25-35% of total project cost saved)– Raytheon: pre-1988: 43% of software cost in defect

correction– 1994 (after software reviews instituted): 5% of project

cost in defect correction

Writing Issues

• Groups of 3

• I’ll give you an issue from an issue list,

• You tell me what’s wrong with it.

• Issues (and responses) from Handbook of Walkthroughs, Inspections, and Technical Reviews, Daniel Freedman and Gerald Weinberg, 3rd Ed, Dorset House.

Writing Issues #1

Some of the explanations of user commands were misinterpreted by members of the review committee.

Comments on Issues #1

Not specific enough. Which explanations were misinterpreted? Don’t make the producers guess, or they may change the wrong thing.

Writing Issues #2

A maximum of 10 values may be specified even though none of the standard system ABEND codes has been made not eligible.

Comments on Issues #2

In writing, clarity isn’t the most important thing: it’s the only thing. If you don’t want to be not understood, don’t never use no double negatives.

Another thing– what is the issue anyway? Is the maximum too low? Too high? Or is it that some of the codes should have been made not eligible? Or eligible? Be direct.

Writing Issues #3

The referenced table of constant values was not part of the review packet.

Comments on Issues #3

Always give the most direct reference available. There could be more than one table, now or in the future. Why make the producers search?

Writing Issues #4

The method used for maintaining the message queue seems to solve a severe performance problem we’ve been having with the production version of the RKY system.

Comments on Issues #4

This is an interesting observation, clearly and directly stated. But what does it have to do with the product under review? It might be worth millions, but it doesn’t belong on the Issues List for this product. It should go on the Related issues list.

More issues #5

The price/performance table should be sorted using either Quicksort or Shell sort.

Comments #5

Raise issues, but avoid all temptation to give advice in the Issues List. They won’t be welcome if they come in that form, so if you really must give advice, find some unofficial vehicle. Take the producers to lunch, or out for a beer, before you share your vast experience on matters of sorting. If your idea isn’t worth the price of a beer, why not forget it?

More issues #6

The three diagrams drawn by Harold Mitter are not in the standard format (DS-109) required for such diagrams in our installation.

Comments #6

This point is nicely specific, but why do we have to mention poor Harold? We are reviewing the product, not the people. Find another way to identify the diagrams and leave people’s names out of the Issues List.

More issues #7

The committee was unable to understand the significance of paragraph 3.1.

Comments #7

Nothing’s wrong with this one. It’s specific about which paragraph is under discussion, and it says the committee doesn’t understand it. Who can argue with that? Yet, surprisingly, people seem to be afraid to express issues this way – “We don’t understand …” Don’t worry about being thought stupid.

If you don’t understand it, it’s at least a potential issue in documentation. And besides, lack of understanding may mean there is something dreadfully wrong.

Yet more issues #8

The bubble sort used for sorting the table of price/performance figures is a stupid approach if the table should grow any bigger than the present 20 entries.

Comments #8

The word “stupid” doesn’t add anything at all and might antagonize the producers. Take it out. Then try to express factually and quantitatively why the method is inappropriate for larger tables.

And if the approach is stupid, what of it? As Arthur C. Clarke expressed it, “It has yet to be proved that intelligence has any survival value.”

Yet more issues #9

If the BY NAME option is not used, the structuring of the structure operands must be equivalent to the structuring of the structures in the arrays of structures.

Comments #9

This wasn’t really taken from an Issues List, but from an old PL/I manual. Still, I’ve read real issues that were almost as obscure. I’d advise you to follow the KISS axiom (“Keep It Simple, Stupid), except that I would be contradicting my own advice from the previous question.

Yet more issues #10

Frieda Sonntag has no computer science background, and her experience with PL/I is nil. She should never have been assigned the coding of this module.

Comments #10

It’s non of the business of the review committee who management has assigned to particular jobs. The committee’s business is to review the product and tell what state it’s in. How it got to that state is another issue—and not for the Issues List. Who is responsible is even less of an issue, and raising it is sure to be ineffective.