Java Reference
In-Depth Information
out.println("<BODY BGCOLOR=#C0C0C0>");
out.println("<H2>Exception Occurred</H2>");
out.println(theException);
out.println("</BODY></HTML>");
} catch (Throwable exception) {
theException.printStackTrace();
}
}
}
The rest of the method catches our exceptions.
5.2.5
Performance problems
This solution has a critical flaw: Most of the cycles will be wasted fetching the
same values. With caching, the customer realized an improvement from an
average of 19 seconds to a subsecond average response time. This is not at all
unusual. Notice the communication between our command object layer and
the database. This communication represents most of the expense for the sys-
tem. In this case, we've seen that five distinct communications, or round-trips,
are necessary out of 20. Because a message board can usually fit entirely in
memory, our application is especially sensitive to caching. Without a cache, it
wouldn't be unusual for us to fetch a post hundreds of times, even though the
value remains unchanged. For real-world high-volume Internet applications,
cache solutions can be considerably faster.
5.3
Solution: Cache
With a sick feeling, I gaze down the near vertical trail. I then look down at my
magic boots, but they're covered in snow. I make my first turn with no problem
and start to relax. Halfway through the second turn, as I brace to finish round-
ing it off, my magic boots abandon me. I am pointed directly downhill, and I pick
up too much speed before falling spectacularly, but softly, in the fresh powder. My
poles and skis have abandoned me at various places along the trail. With great
effort, I dig through the snow, gather my gear, and start down the hill once more.
Turn. Brace. Poof. Yard sale. After collecting my gear—and what is left of my
dignity—I try again. I crash again. My normally calm demeanor shattered, I let
out a long string of profanities. When certain geologic conditions exist, echoes
carry surprisingly well. I am certain that mine carry to all of the amused Utah
residents around the easy slope that skirt my canyon.
I've never had a more acute sense of embarrassment than I did on that moun-
tain slope in Utah. After I was back in the ski lodge and thinking more clearly,
