The I.T. Girl by Fiona Pearse Read Free Book Online Page B

was one of the few people who used the room for its actual purpose – somewhere
to concentrate, away from the noise.
    He looked up to see me coming over. ‘So, how are you enjoying
your first live problem?’
    I sat next to him and clicked my heels three times. ‘If today
gets any worse I'm going to have an out of body experience.’
    ‘That’s what happens when you let women write software.’
    ‘So you’re enjoying this?’
    ‘Anything come up yet?’ He relaxed his pen on the page.
    ‘No. Definitely looking like there’s an obscure bug in my code,
but I’ve been staring at it for so long it’s become meaningless. Could we step through
it together?’
    ‘Sure,’ he nodded.
    ‘Thanks. So, how’s it going?’ I looked at his notepad.
    ‘Good. Should need a review soon.’ He
held across the pages of arrows and squares.
    ‘Looks complex.’ I reached over to turn
the pages in his hand.
    The grad in the corner swore at his trick and tried walking the
dog again.
    ‘I better go back,’ I said. ‘See you at my desk in five?’
    ‘Yeah I’ll come round. Want me to get you something? A coffee?’
    ‘No, thanks. I’ve just been to the canteen.’
I stood up with a dramatic sigh and went back out to the floor.
    At my desk I opened my files for Sam’s inspection.
    ‘You know the story so far?’ I asked as he came over.
    ‘Yeah, I’ve been reading your updates.’ He pulled up the spare
chair and we leaned our heads into the fluorescent screens. The code I had opened
up was spread out over three monitors. It curved from one end of the desk to the
other. Sam squinted, leaning in and I allowed his hand take the mouse from mine.
    Trouble-shooting was like going through a maze. Following each
turn and remembering the way back to the starting point if you reached a dead end.
The trick was to block out assumptions, try to forget everything you knew, and look
at things freshly each time.
    ‘It’s got to be something basic you do for every single packet.’
Sam snatched up the diagram we had drawn together. We had exhausted all the possibilities
and were back at the start again.
    ‘The only thing I do for every packet is generate an ISIN. I
add one to each Order before it’s sent to Desktop... Let’s look at the ISIN Generator
code.’ I took the mouse, forcing myself into another burst of energy and opened
more files on the screen.
    ‘It looks fairly clean.’ Sam blinked in the florescent light.
I noticed his eyes were watery. ‘What’s this search?’ he highlighted a line of code.
    ‘That’s just the search function to retrieve an ISIN. If there
isn’t an appropriate one already in the list, a new one gets generated... Oh, that’s
odd... That should be a binary search,
not the standard find .’
    ‘Is it on a map or vector?’
    ‘A sorted vector.’
    We both stopped talking. It was clear what the problem was. I
was using the slowest possible search algorithm trying to find one entry in a huge
list, and it was happening for every single order.
    ‘No wonder orders aren’t being processed fast
enough,’ I squawked. ‘The list of ISINs can grow up to tens of thousands
of entries throughout the day!’
    Sam slumped back in his chair, causing it to moan. ‘At least
it should be a simple fix,’ he said lifelessly. ‘Run your performance tests again
using a binary search. I bet even on a small amount of data you’ll see a difference.’
    ‘I can’t believe I made such a stupid mistake.’
    ‘Who did your code review?’
    ‘Boris.’
    ‘He wouldn’t know the difference.’
    I thought back to my code review. I had left early, flying home
that night for a long weekend. I remember I had emailed Boris some quick notes about
what to look for. ‘I’m an idiot.’
    ‘Don’t worry about it,’ Sam said. ‘It’s a mistake. It could happen
to anyone.’
    I changed my code and re-tested. Sure enough, the speed of the
new search was noticeably faster. I could have kicked myself. The whole time I