When IT Goes BadFrom Software to Society

Fluency with Information Technology

2012-04-20 Katherine Deibel, Fluency in Information Technology 1

INFO100 and CSE100

Katherine Deibel

Errors and IT

Basic fact: Technology can go bad At least two sources of fault

How the technology operates

How people use the technology At least two forms of correction

Debugging

IT Fluency

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Understanding ErrorsOoops…

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4

The Infamous Bug

While working on the Mark II, Grace Hopper discovered a moth stuck in a relay that had caused an electric short

Originated the term “debugging”

2012-04-20 Katherine Deibel, Fluency in Information Technology

Replicating Errors

By replicating, you can Learn factors that led to the error

Eliminate erroneous correlations Some errors you do not want to

replicate/cannot replicate Install corruptions

Hard drive crashes

Explosions

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Some Errors are Random

Cosmic "rays" Energetic charged particles from space

Usually blocked by the Earth's magnetic field and atmosphere

More prevalent during solar storms and/or at higher altitudes

When they collide with electronics Can cause bit flips (01 or 10)

Lead to essentially random errors

Rare but not unknown

2012-04-20 Katherine Deibel, Fluency in Information Technology 6

Some Errors are Chaotic

Chaos ≠ Random Chaos means that the patterns are

very complex and difficult to pin down Therac-25 errors were fairly chaotic

Some errors only occur when specific factors are in play Problems with copy/paste in Excel if I

have macros enabled plus the Chrome browser is running

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Some Errors are Annoying

Some errors disappear when you try to investigate them Called 'Heisenbugs' after the Heisenberg

Uncertainty Principle By observing what is going on on your

computer, you change some factors Those factors are what were causing the bug

Typically, these are the rarest and hardest bugs to address

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Implications

Some errors are only one-time events Difficult to replicate

Due to randomness, chaos, or a heisenbug When an error occurs

Step back and observe what happened

Recall what you were doing

Recall what the computer was doing (beyond just the active window)

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Error-Correction

Computers can be designed to correct specific errors Parity checks for flipped bits due to cosmic rays

Browsers render invalid XHTML Computers only detect errors that they

are told to look out for The computer's correction may not be

what you want it Remember: Garbage In Garbage Out

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DebuggingTHE ANTS… THEY'RE IN

MY PANTS!!!

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General Principles of Debugging

Do not panic (unless something is on fire) Observe what happened, what did not Note any error messages Work from the most likely causes down to

the least likely causes When in doubt, seek help

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Many Types of Debugging

Programming Debugging Writing HTML, CSS, Javascript, etc.

Software Malfunction Program crashes, feature doesn't work

as expected, etc. Hardware Debugging

Printer will not print

Wireless will not connect

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Your Role as the Debugger

Programming Debugging You are the chief mechanic

Software and Hardware Mechanic Your role is much more limited

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Historically, it was much, much easier for people without technical degrees to perform repairs on home electronics: televisions, radios, etc.

Programming Debugging

Ignore the number of errors Remember, errors propagate errors

Start with the error that first occurs Again, errors propagate errors

If there is error feedback, read it! Make a fix and then check

Do NOT fix repeated errors unless you are certain that you know the cause

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Example: XHTML Validation

We attempt to validate a page We get 24 errors and warnings.. EEK! What do we do?

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Example: XHTML Validation

We attempt to validate a page We get 24 errors and warnings.. EEK!

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Ignore the number of errors

Example: XHTML Validation

First error reported is an <h1> tag

<h1 class="banner>…</h1> We put in the missing quote

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Start with the first occurring error

Example: XHTML Validation

We save and revalidate Only 4 errors and warnings now

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Make a fix and then check

Example: XHTML Validation

All of our errors now look like this We need to put <img> inside <p>…

</p> We can do this for all four

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Line 11, Column 25: document type does not allow element "img" here; missin one of "p", "h1", "h2", "h3", "h4", "h5", h6", "div", "pre", "address", "fieldset", "ins", "del" start-tag

... <img src="photo.png" alt="a cute calico cat" />

Only fix multiple errors if certain of cause

Software/Hardware Debugging

Much more difficult If possible, first save and backup your work Look around and see what you know Read the screen

Write down any error messages to look up online

Is there a pointer/link that offers help When in doubt, restart

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Katherine Deibel, Fluency in Information Technology 22

The Levels of Restart

Close and restart the program Might need to close in Task Manager (Windows)

Log out and log back in Restart the machine (hot reboot) Shutdown the machine, wait a few

minutes, then restart (cold reboot)

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Why Restarting Helps

Think mental exhaustion When programs run

Memory gets allocated and deallocated (available for others to use)

Memory is not cleared when deallocated Legacies of past calculations build up

Minor things begin to snowball

Entropy ensues

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Why Restarting Helps

Helps flush away the clutter, clears the board, etc.

Power down causes most volatile memory to "zero" out

Basically gives programs a do-over, mulligan, fresh start, etc.

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Seeking Out Help● ● ● − − − ● ● ●

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Finding Answers on the Web

If you have an error message, use that text plus the program name:excel 2010 vba error 1045

Otherwise, try to describe the error and search with the program name or computer type:thinkpad t410 keyboard "poiurewq"

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Find Specific Forums

Many computer and software companies have support sites FAQs for searching

Message boards

Online support chat

Updates (software, drivers, etc.)

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Ask a Computer Buddy

Two minds are better than one Does not necessarily mean you need

to find an 'expert' Experience is often better than a degree

Peers are often trying to do similar tasks

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But I must whine…Why bugs will always occur

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IT Cannot Be Perfect

Bugs, errors, etc. cannot be avoided beyond very simple situations Proven to be mathematically impossible

Unless you invoke a god-like being

But you cannot prove the god-like being will always work

Unless you invoke a god-like, god-like being…

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We Do Our Best

Software engineering Testing before products hit market Upgrades and fixes Risk assessments and failure cost

analyses

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Debugging will always be necessary

Summary

IT can and does go wrong at times. Debugging can help you fix the problems You just need to observe and think

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