Re: StringBuffer pools and why not to use them

[Jerome Lacoste @ BBC]

Robert Simmons wrote:

Well now ... I think this post goes a bit far. At least he tried the task before
advocating it. The fact is that a large number of people poorly use StringBuffer
anyway. This could account for performance hits. The simple line of code that
you see all the time like:

StringBuffer buf = new StringBuffer(500);
buf.append("This is a test under " + System.getProperty("os.arch") +
                 " operating system, version " +
System.getProperty("os.version"));

This code has a serious problem. Since you are so busy calling others idiots,
can you tell us all why ?

There are two bad things:
- too much allocation
- no use of the append() methods

Both make the calls slower. On my machine, reducing the size of the StringBuffer to 80 (*) helps as much as using append() correctly.

(*) could have used a different value there. Just knowing that doMe() returns a String of length 54 on my VM

Looping 100000 times around a call to these methods

public static String doMe()
{
StringBuffer buf = new StringBuffer(500);
buf.append("This is a test under " + System.getProperty("os.arch") +
" operating system, version " +
System.getProperty("os.version"));
return buf.toString();
}

public static String doMeBetter()
{
StringBuffer buf = new StringBuffer(500);
buf.append("This is a test under ").append(System.getProperty("os.arch"));
buf.append(" operating system, version ").append(System.getProperty("os.version"));
return buf.toString();
}

public static String doMeEvenBetter()
{
StringBuffer buf = new StringBuffer(80);
buf.append("This is a test under ").append(System.getProperty("os.arch"));
buf.append(" operating system, version ").append(System.getProperty("os.version"));
return buf.toString();
}

Results:


DoMe() count: 4500
DoMeBetter() count: 3234
DoMeEvenBetter() count: 1704
DoMe() count: 4500
DoMeBetter() count: 3218
DoMeEvenBetter() count: 1703
DoMe() count: 4563
DoMeBetter() count: 3203
DoMeEvenBetter() count: 1734

-- Robert

"Chris Duprat" <[EMAIL PROTECTED]> wrote in message
005001c2d76c$a542bf50$8dfb0d50@zzz">news:005001c2d76c$a542bf50$8dfb0d50@zzz...

Wasting of time. You shouldn't have the idea of implementing a pool for such
objects because of their high availability. By adding another level you just
reach the performance issue which is critical for that kind of objects.

You're an Idiot ;-)
http://www.pagetutor.com/idiot/idiot.html

BTW, click on on the page anywhere, drag your mouse over the button and release click at once to win ;)


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