ASP Performance

[Roland Hall]

I've read numerous articles, more than I can count, on ASP performance. I
see conflicting information so I did some tests on my own.

getstring and getrows are actually faster than recordset looping.

However, I've read in looping that Do While...Loop is the fastest and
For...Next the slowest but my tests prove otherwise.

I've tested:
Do...Loop
Do While...Loop
Do Until...Loop
While...Wend
For...Next

I didn't think I could do an accurate test with For...Each unless I used a
collection or an array.

I also see conflicting information on string concatenation and
Response.Write

Is this better?

dim str
str = str & "this "
str = str & "that "
str = str & "this and that"
Response.Write str

or this?

dim str
Response.Write "this "
Response.Write "that "
Response.Write "this and that"

I've also seen to speed the last one up:

with Response
.Write "this "
.Write "that "
.Write "this and that"
end with

Are there reliable performance tests that can be reviewed?
Does it vary between languages? ASP:VBscript, ASP:JScript, C/C++, Delphi,
VB, C#

--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */
Technet Script Center - http://www.microsoft.com/technet/scriptcenter/
WSH 5.6 Documentation - http://msdn.microsoft.com/downloads/list/webdev.asp
MSDN Library - http://msdn.microsoft.com/library/default.asp

[Dave Anderson]

Roland Hall wrote:

Is this better?

dim str
str = str & "this "
str = str & "that "
str = str & "this and that"
Response.Write str

or this?

dim str
Response.Write "this "
Response.Write "that "
Response.Write "this and that"

Most definitely this is better than this.

--
Dave Anderson

Unsolicited commercial email will be read at a cost of $500 per message. Use
of this email address implies consent to these terms. Please do not contact
me directly or ask me to contact you directly for assistance. If your
question is worth asking, it's worth posting.

[Roland Hall]

"Dave Anderson" wrote in message
news:ec******** ******@TK2MSFTN GP14.phx.gbl...
: Roland Hall wrote:
: > Is this better?
: >
: > dim str
: > str = str & "this "
: > str = str & "that "
: > str = str & "this and that"
: > Response.Write str
: >
: > or this?
: >
: > dim str
: > Response.Write "this "
: > Response.Write "that "
: > Response.Write "this and that"
:
: Most definitely this is better than this.

What this settles this but how about that?

--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */
Technet Script Center - http://www.microsoft.com/technet/scriptcenter/
WSH 5.6 Documentation - http://msdn.microsoft.com/downloads/list/webdev.asp
MSDN Library - http://msdn.microsoft.com/library/default.asp

[Bob Barrows [MVP]]

Roland Hall wrote:

I've read numerous articles, more than I can count, on ASP
performance. I see conflicting information so I did some tests on my
own.

getstring and getrows are actually faster than recordset looping.

However, I've read in looping that Do While...Loop is the fastest and
For...Next the slowest
I've never seen that anywhere. Do you have a cite?
but my tests prove otherwise.

I've tested:
Do...Loop
Do While...Loop
Do Until...Loop
While...Wend
For...Next

I didn't think I could do an accurate test with For...Each unless I
used a collection or an array.

I also see conflicting information on string concatenation and
Response.Write

Is this better?

dim str
str = str & "this "
str = str & "that "
str = str & "this and that"
Response.Write str

or this?

dim str
Response.Write "this "
Response.Write "that "
Response.Write "this and that"

I've also seen to speed the last one up:

with Response
.Write "this "
.Write "that "
.Write "this and that"
end with

Chris Hohmann (I think) posted the definitive analysis on this some time
ago. I don't have tome to go looking for it now, but maybe he'll pop in.
Regarding the With...End With, reducing the dots that need to be resolved
will speed things up, but
1. In vbscript, it's unlikely to be very noticeable
2. there is a threshold before which no performance enhancement will be
seen. I've seen 5 dot eliminations as the threshold but I really don't think
this has been nailed down by anyone.

Bob Barrows
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get a
quicker response by posting to the newsgroup.

[Roland Hall]

"Bob Barrows [MVP]" wrote in message
news:up******** ******@tk2msftn gp13.phx.gbl...

Thanks for responding...

: Roland Hall wrote:
: > I've read numerous articles, more than I can count, on ASP
: > performance. I see conflicting information so I did some tests on my
: > own.
: >
: > getstring and getrows are actually faster than recordset looping.
: >
: > However, I've read in looping that Do While...Loop is the fastest and
: > For...Next the slowest
:
: I've never seen that anywhere. Do you have a cite?

I think I had that wrong. I never found the article I thought I remembered
reading. Now I'm wondering if I was high. It must have been between Do
While...Loop and While...Wend and may not have been a speed comparison. If
you see my mind, please post it here. I miss it.

: > but my tests prove otherwise.
: >
: > I've tested:
: > Do...Loop
: > Do While...Loop
: > Do Until...Loop
: > While...Wend
: > For...Next
: >
: > I didn't think I could do an accurate test with For...Each unless I
: > used a collection or an array.
: >
: > I also see conflicting information on string concatenation and
: > Response.Write
: >
: > Is this better?
: >
: > dim str
: > str = str & "this "
: > str = str & "that "
: > str = str & "this and that"
: > Response.Write str
: >
: > or this?
: >
: > dim str
: > Response.Write "this "
: > Response.Write "that "
: > Response.Write "this and that"

No info on the string concat?
: > I've also seen to speed the last one up:
: >
: > with Response
: > .Write "this "
: > .Write "that "
: > .Write "this and that"
: > end with
: >
: Chris Hohmann (I think) posted the definitive analysis on this some time
: ago. I don't have tome to go looking for it now, but maybe he'll pop in.
: Regarding the With...End With, reducing the dots that need to be resolved
: will speed things up, but
: 1. In vbscript, it's unlikely to be very noticeable
: 2. there is a threshold before which no performance enhancement will be
: seen. I've seen 5 dot eliminations as the threshold but I really don't
think
: this has been nailed down by anyone.

Are you saying without at least 5 statements, using with won't be a benefit,
re: threshold?

--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */
Technet Script Center - http://www.microsoft.com/technet/scriptcenter/
WSH 5.6 Documentation - http://msdn.microsoft.com/downloads/list/webdev.asp
MSDN Library - http://msdn.microsoft.com/library/default.asp

[Bob Barrows [MVP]]

Roland Hall wrote:

"Bob Barrows [MVP]" wrote in message
news:up******** ******@tk2msftn gp13.phx.gbl...
No info on the string concat?

That's what I was referring to here:
*************** *************** ***************

Chris Hohmann (I think) posted the definitive analysis on this some
time ago. I don't have tome to go looking for it now, but maybe
he'll pop in. *************** *************** ***************

Regarding the With...End With, reducing the dots that
need to be resolved will speed things up, but
1. In vbscript, it's unlikely to be very noticeable
2. there is a threshold before which no performance enhancement will
be seen. I've seen 5 dot eliminations as the threshold but I really
don't think this has been nailed down by anyone.

Are you saying without at least 5 statements, using with won't be a
benefit, re: threshold?

No, I meant without at least 5 dot-resolutions. There can be more than one
resolution per line, as in:

With document.all.ta bles(0).rows(0)
.style.backgrou ndcolor="silver "
.style.color="r ed"
end with

This avoids 3 dot-resolutions per line, so the threshold is passed. Again,
in vbscript, the difference will be negligible.

Bob Barrows
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get a
quicker response by posting to the newsgroup.

[Roland Hall]

"Bob Barrows [MVP]" wrote in message
news:uY******** *****@TK2MSFTNG P12.phx.gbl...
: Roland Hall wrote:
: > "Bob Barrows [MVP]" wrote in message
: > news:up******** ******@tk2msftn gp13.phx.gbl...
: >
: >
: > No info on the string concat?
: >
: That's what I was referring to here:
: *************** *************** ***************
: >> Chris Hohmann (I think) posted the definitive analysis on this some
: >> time ago. I don't have tome to go looking for it now, but maybe
: >> he'll pop in.
: *************** *************** ***************

Thanks for clearing that up.

: >> Regarding the With...End With, reducing the dots that
: >> need to be resolved will speed things up, but
: >> 1. In vbscript, it's unlikely to be very noticeable
: >> 2. there is a threshold before which no performance enhancement will
: >> be seen. I've seen 5 dot eliminations as the threshold but I really
: >> don't think this has been nailed down by anyone.
: >
: > Are you saying without at least 5 statements, using with won't be a
: > benefit, re: threshold?
: >
: No, I meant without at least 5 dot-resolutions. There can be more than one
: resolution per line, as in:
:
: With document.all.ta bles(0).rows(0)
: .style.backgrou ndcolor="silver "
: .style.color="r ed"
: end with
:
: This avoids 3 dot-resolutions per line, so the threshold is passed. Again,
: in vbscript, the difference will be negligible.

And that...

--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */

[Dave Anderson]

Roland Hall wrote:

Is this better?

dim str
str = str & "this "
str = str & "that "
str = str & "this and that"
Response.Write str

or this?

dim str
Response.Write "this "
Response.Write "that "
Response.Write "this and that"

Seriously, I believe the second offers better performance. You could easily
test this with a large array or recordset. I tested it in JScript by reading
a SQL table of 5780 quotes totalling 357,886 bytes, or roughly 62 characters
each. To simplify testing, I dumped them into a simple JScript array and
timed the following on some old hardware, on IIS 4/5/6 and with buffering
on/off:

1. for (var i=0; i<a.length; i++) Response.Write( a[i])
2. for (var i=0; i<a.length; i++) str += a[i]; Response.Write( str)
3. Response.Write( a.join(""))

Average results (10 passes):

//--- Dual XEON 550, 768MB RAM, Windows NT Server 4.0 ---//
Case Response.Buffer = true Response.Buffer = false
1. 172ms 390ms
2. 35365ms 35146ms
3. 78ms 109ms

//--- Single XEON 550, 1GB RAM, Windows 2000 Server ---//
Case Response.Buffer = true Response.Buffer = false
1. 141ms 1688ms
2. 29343ms 29177ms
3. 47ms 98ms

//--- Single XEON 550, 1GB RAM, Windows Server 2003 ---//
Case Response.Buffer = true Response.Buffer = false
1. 174ms 500ms
2. 30658ms 30540ms
3. 65ms 73ms
As you can see, concatenation is the biggest hurdle to performance, and
Array.join() beats iteration. The buffering results are self-explanatory,
though I was shocked to see how badly IIS 5 performs with buffering off[1].

I understand that in JScript, Response.Write is late-bound, which accounts
for the big difference between 1 and 3. IIRC, the same test in VBScript
yields a different result altogether. But my memory isn't what it used to
be, so I tested in IIS 6 with buffering on. I found these results[2]:

Case Response.Buffer = true
1. 50ms
2. 16912ms
3. 41ms

Once again, concatenation destroys performance, and Join() still beats
iteration.

On a side note, I compared GetRows() to GetString() for this exercise, and
GetRows() + iteration blew GetString() away. I do not speculate whether this
would be true for a recordset with multiple columns.

[1] Compared to IIS 4 and 6, that is
[2] VBScript cases:
1. For i=0 To UBound(a) : Response.Write( a(i)) : Next
2. For i=0 To UBound(a) : str = str & a(i) : Next : Response.Write( str)
3. Response.Write( Join(a))

--
Dave Anderson

Unsolicited commercial email will be read at a cost of $500 per message. Use
of this email address implies consent to these terms. Please do not contact
me directly or ask me to contact you directly for assistance. If your
question is worth asking, it's worth posting.

[Chris Hohmann]

"Bob Barrows [MVP]" <re******@NOyah oo.SPAMcom> wrote in message
news:up******** ******@tk2msftn gp13.phx.gbl...

Chris Hohmann (I think) posted the definitive analysis on this some time
ago. I don't have tome to go looking for it now, but maybe he'll pop in.

[snip]

I'm not sure how definitive it was, but I think this is the thread you're
talking about:
http://groups-beta.google.com/group/...9c1498e99d805e

And to be fair, Dave Anderson should get equal billing for this thread.

[Chris Hohmann]

"Dave Anderson" <GT**********@s pammotel.com> wrote in message
news:uv******** ******@TK2MSFTN GP14.phx.gbl...

On a side note, I compared GetRows() to GetString() for this exercise, and
GetRows() + iteration blew GetString() away. I do not speculate whether
this would be true for a recordset with multiple columns.

You can side step the string buffer allocation issue with GetString making
use of the NumRows parameter to output in bursts.