■ INTRODUCTION
xxii
is problem has drifted up through schools and into universities. Teaching programming is a relatively
challenging task. It requires a certain way of thinking that for many people is tough to get a handle on. Traditionally,
universities would start a computer science course by teaching about logic gates, how memory works, and how to
program a CPU. Only once you understood what the bare metal was doing would you try to learn C because although
C is a higher language, it reects the hardware it runs on. Understanding the hardware makes understanding C that
much easier.
But with larger class sizes, more limited teaching time, and students arriving with less and less knowledge of
computing fundamentals, universities have had to adapt. Rather than teaching all that low-level stu, now they teach
Java and other scripting languages. Because these languages handle all of the “ddly bits” for you, you can eectively
pretend that they don’t exist (although this can cause some issues; see “e Innite Memory Myth”).
is is simply fantastic from a productivity point of view, but when you do want to take it to the next level (maybe
you’re processing data and your script is just too slow), you have no idea where to turn. Worse, when someone tells
you the technique for improving that performance, you have no idea what they’re talking about.
Of course not all universities have taken this route. I’m studying at the Hong Kong Polytechnic University, and its
course on Computer Architecture is very detailed and covers a lot of ground. If you want to get the top grade, you will
need to implement a CPU cache for the CPU simulator program. Needless to say, there is a lot to learn for everyone on
this course. at said, we need more than this. It’s too late to capture people’s interest when they’re starting graduate
studies. I taught seven-year-olds how to program BBC BASIC when I was in my last year of primary school (they even
got presented certicates by the school) and they loved it. Computing lets you create a virtual world with your mind
(the children liked to create little text–based adventure games) and ultimate power rested in their hands. ey got
creative; they added spells, new roads, secret entrances, and much more. Okay, they needed a helping hand (they
were only seven) but they had the desire to create and to build cool new things.
INFINITE MEMORY MYTH
Over the years, I’ve done a lot of consultancy work with large enterprise customers and that has inevitably meant
I’ve come across Java on many occasions. One of the interesting things I have come across is what I’ve termed
the Infinite Memory Myth. This seems to crop up more in Java applications than in other languages, but that’s
probably because Java tends to be more widely used in those settings.
The short version of the myth is that developers seem to constantly create new objects, often to the point where
the application consumes huge amounts of memory or crashes altogether. They tend to have no idea how much
memory each object takes or, more worryingly, why they should care. As far as they are concerned, they request a
new object and one is provided. When an object is no longer used (i.e., nothing points to it any more), Java will at
some point get around to cleaning it up (called garbage collection). All of this is automatic; the developer doesn’t
need to do anything.
The problem is that this leads people to forget (or in many cases were never taught at all) that memory is finite,
and at some point it simply runs out. You can’t assume that you can read in every row in a table and that it will
always work. You can’t assume that just because your test file is 50MB in size that the application will never be
given a 5,000MB file to work on.
This lack of understanding stems from not being able to appreciate all the hard work Java is doing on the
programmer’s behalf. It is running about and managing memory allocation and garbage collection, and the
programmer remains blissfully unaware. A good understanding of computing fundamentals would give a
developer keen insight into what Java is doing (both the how and the why) and thus appreciate that just because
creating new objects is easy, memory itself is not free.
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