Web Performance Tuning, 2nd edition
by Patrick Killelea

The unconfirmed error reports are from readers.  They have not yet been 
approved or disproved by the author or editor and represent solely the
opinion of the reader.

Here's a key to the markup:
        [page-number]: serious technical mistake
        {page-number}: minor technical mistake
        <page-number>: important language/formatting problem
        (page-number): language change or minor formatting problem
        ?page-number?: reader question or request for clarification

This page was updated May 29, 2002.


UNCONFIRMED  errors and comments from readers: 


(23)  4th paragraph;
It well known

	should be:

It is well known


(38)  3rd paragraph;
technologies give users

	should be:

technologies that give users


(42)  9th paragraph;
respective chapters in of

	Should be:

respective chapters of


(112)  4th paragraph;
reviews of the some standard

	Should be:

reviews of some of the standard

(158)  5th paragraph;
dependence in optimizations

	Should be:

dependence on optimizations

(255)  4th paragraph;
$ java  EcoServer 8888

	Should be:

$ java  EchoServer 8888


{279}  2nd paragraph;
Quote:

    "If we compile this and run one thread under Sun's Java 1.1.7 on
     a 4-CPU Sun machine the execution time is 13 seconds:"

Note that this does not include startup costs (the time required to
set up the Java Virtual Machine, load the class file, instantiate
any objects, and create the main thread). These can be estimated as
shown below (obviously the absolute time value is not comparable, as
both the hardware and the Java Virtual Machine differ). To estimate
the Java Virtual Machine setup time:

    martin@living:~/WebPerf/ch16> time java -version
    java version "1.4.0"
    Java(TM) 2 Runtime Environment, Standard Edition(build 1.4.0-b92)
    Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)

    real    0m1.677s
    user    0m1.620s
    sys     0m0.040s

And because the bulk of the processing is performed by the threads
(the main method merely launches the threads - at 50 milliseconds or
so, this can be ignored), a better measure of the overall startup
costs (the Virtual Machine, plus class loading, object creation and
the main thread) can be derived as follows:

    martin@living:~/WebPerf/ch16> time java Loop 0

    real    0m2.265s
    user    0m2.140s
    sys     0m0.110s

These costs will be relatively constant for any number of threads,
and can be safely ignored for performance purposes when amortized
over many threads.

This is not really a technical mistake (possibly it's an omission),
but I thought it was interesting enough to include here for others
to read.

(312)  3rd paragraph;
"The <i>java.awt</i> package needs to open an X display to render GIF
images, even if the image is generated off-screen."

With the recent release of Java 1.4, 'headless' (i.e. no X display)
operation is theoretically possible. The following link offers more
information:

http://java.sun.com/j2se/1.4/docs/guide/awt/AWTChanges.html#headless

This is obviously not a 'language change or typo', merely a recent
development that might be of interest.



{409}  3rd paragraph;
Compile with 'java jdbcCxnTest'.

	Should be:

Compile with 'javac jdbcCxnTest.java'. Obtain a usage message with
'java jdbcCxnTest'.


(414)  4th paragraph;
intgrate

	Should be:

integrate


(417)  5th paragraph;
10,00PCs?

	Should be:

1,000 PCs?

(423)  4th paragraph;
with Resonate that

	Should be:

with Resonate is that