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asp_web_howto thread: Memory Leaks
Message #1 by rg1@h... on Fri, 24 Aug 2001 16:54:13
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Hi.
I have a question regarding memory leaks.
If I have Page1.asp that sets a reference to Object1, then Page1.asp
encounters an error which will redirect to another page, thus bypassing
the statement in Page1.asp to "Set Object1 = Nothing", will this cause a
memory leak?
I could, before redirecting, use a "subDispose(ObjToDispose)" for each
reference set, but wondered if this was necessary.
TIA.
Rita
Message #2 by "Ken Schaefer" <ken@a...> on Mon, 27 Aug 2001 15:06:29 +1000
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ASP is *supposed* to have it's own garbage collection. However, it is always
good programming practice to clean up after yourself explicitly.
That said, why redirect? I usually have something like this:
<%
Function fncWhatever( _
)
On Error Resume Next
Const Proc = "fncWhatever"
...
If Err.Number <> 0 then
Call subErrorHandler(Err.Number, Proc, Err.Description)
End If
End Function ' fncWhatever
Sub subErrorHandler( _
ByVal strErrNum, _
ByVal strErrSource, _
ByVal strErrDescrip _
)
' Clear existing Response Buffer
Response.Clear
Call subWritePageHeading()
Call subWritePageBody()
With Response
.Write("<p>An error occured:<br>" & vbCrLf)
.Write("Err Number: " & strErrNum<br>" & vbCrLf)
.Write("Err Source: " & strErrSource<br>" & VbCrLf)
.Write("</p>" & vbCrLf)
End With
Call subWritePageFooter()
Response.Flush
Response.End
End Sub ' subErrorHandler
%>
Of course, subErrorHandler would be in an include file that you just include
on every page...
Cheers
Ken
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: <rg1@h...>
To: "ASP Web HowTo" <asp_web_howto@p...>
Sent: Friday, August 24, 2001 4:54 PM
Subject: [asp_web_howto] Memory Leaks
: Hi.
:
: I have a question regarding memory leaks.
:
: If I have Page1.asp that sets a reference to Object1, then Page1.asp
: encounters an error which will redirect to another page, thus bypassing
: the statement in Page1.asp to "Set Object1 = Nothing", will this cause a
: memory leak?
:
: I could, before redirecting, use a "subDispose(ObjToDispose)" for each
: reference set, but wondered if this was necessary.
:
: TIA.
:
: Rita
Message #3 by Rita Greenberg <rg1@h...> on Mon, 27 Aug 2001 07:16:50 -0700
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Thanks Ken for the sample code. I use something very similar except Redirect
instead of just calling the sub. The sub is the best way to go so everything
gets cleaned up.
Just a matter of interest. I noticed that you broke down the arguments
passed to subErrorhandler "Err.Number" and "Err.Description". I just pass
the whole Err object. Is your example more efficient?
Rita
-----Original Message-----
From: Ken Schaefer [mailto:ken@a...]
Sent: Sunday, August 26, 2001 10:06 PM
To: ASP Web HowTo
Subject: [asp_web_howto] Re: Memory Leaks
ASP is *supposed* to have it's own garbage collection. However, it is always
good programming practice to clean up after yourself explicitly.
That said, why redirect? I usually have something like this:
<%
Function fncWhatever( _
)
On Error Resume Next
Const Proc = "fncWhatever"
...
If Err.Number <> 0 then
Call subErrorHandler(Err.Number, Proc, Err.Description)
End If
End Function ' fncWhatever
Sub subErrorHandler( _
ByVal strErrNum, _
ByVal strErrSource, _
ByVal strErrDescrip _
)
' Clear existing Response Buffer
Response.Clear
Call subWritePageHeading()
Call subWritePageBody()
With Response
.Write("<p>An error occured:<br>" & vbCrLf)
.Write("Err Number: " & strErrNum<br>" & vbCrLf)
.Write("Err Source: " & strErrSource<br>" & VbCrLf)
.Write("</p>" & vbCrLf)
End With
Call subWritePageFooter()
Response.Flush
Response.End
End Sub ' subErrorHandler
%>
Of course, subErrorHandler would be in an include file that you just include
on every page...
Cheers
Ken
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: <rg1@h...>
To: "ASP Web HowTo" <asp_web_howto@p...>
Sent: Friday, August 24, 2001 4:54 PM
Subject: [asp_web_howto] Memory Leaks
: Hi.
:
: I have a question regarding memory leaks.
:
: If I have Page1.asp that sets a reference to Object1, then Page1.asp
: encounters an error which will redirect to another page, thus bypassing
: the statement in Page1.asp to "Set Object1 = Nothing", will this cause a
: memory leak?
:
: I could, before redirecting, use a "subDispose(ObjToDispose)" for each
: reference set, but wondered if this was necessary.
:
: TIA.
:
: Rita
Message #4 by rg1@h... on Mon, 27 Aug 2001 16:04:31
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Ken, I just had a thought after going back to view your example
subErrorHandler code. After the "Response.End", the error message is
displayed on the screen. How does the control return to the line following
the call to the error handled in fncWhatEver? Is there a button on the
displayed error message screen that when the uses clicks it, control is
returned? This to allow the error message to be displayed long enough for
the user to see it.
Rita
> ASP is *supposed* to have it's own garbage collection. However, it is
always
> good programming practice to clean up after yourself explicitly.
>
> That said, why redirect? I usually have something like this:
>
> <%
> Function fncWhatever( _
> )
>
> On Error Resume Next
> Const Proc = "fncWhatever"
> ...
> If Err.Number <> 0 then
> Call subErrorHandler(Err.Number, Proc, Err.Description)
> End If
> End Function ' fncWhatever
>
> Sub subErrorHandler( _
> ByVal strErrNum, _
> ByVal strErrSource, _
> ByVal strErrDescrip _
> )
>
> ' Clear existing Response Buffer
> Response.Clear
> Call subWritePageHeading()
> Call subWritePageBody()
> With Response
> .Write("<p>An error occured:<br>" & vbCrLf)
> .Write("Err Number: " & strErrNum<br>" & vbCrLf)
> .Write("Err Source: " & strErrSource<br>" & VbCrLf)
> .Write("</p>" & vbCrLf)
> End With
> Call subWritePageFooter()
> Response.Flush
> Response.End
>
> End Sub ' subErrorHandler
> %>
>
> Of course, subErrorHandler would be in an include file that you just
include
> on every page...
>
> Cheers
> Ken
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> From: <rg1@h...>
> To: "ASP Web HowTo" <asp_web_howto@p...>
> Sent: Friday, August 24, 2001 4:54 PM
> Subject: [asp_web_howto] Memory Leaks
>
>
> : Hi.
> :
> : I have a question regarding memory leaks.
> :
> : If I have Page1.asp that sets a reference to Object1, then Page1.asp
> : encounters an error which will redirect to another page, thus bypassing
> : the statement in Page1.asp to "Set Object1 = Nothing", will this cause
a
> : memory leak?
> :
> : I could, before redirecting, use a "subDispose(ObjToDispose)" for each
> : reference set, but wondered if this was necessary.
> :
> : TIA.
> :
> : Rita
>
>
Message #5 by Kyle Burns <kburns@c...> on Mon, 27 Aug 2001 13:14:31 -0500
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In many cases (should be always but doesn't work that way), the err object
is cleared when moving from proc to proc. You're better off persisting the
information into arguments of your error handler.
=================================
Kyle M. Burns, MCSD
ECommerce Technology Manager
Centra Credit Union
kburns@c...
-----Original Message-----
From: Rita Greenberg [mailto:rg1@h...]
Sent: Monday, August 27, 2001 9:17 AM
To: ASP Web HowTo
Subject: [asp_web_howto] Re: Memory Leaks
Thanks Ken for the sample code. I use something very similar except Redirect
instead of just calling the sub. The sub is the best way to go so everything
gets cleaned up.
Just a matter of interest. I noticed that you broke down the arguments
passed to subErrorhandler "Err.Number" and "Err.Description". I just pass
the whole Err object. Is your example more efficient?
Rita
-----Original Message-----
From: Ken Schaefer [mailto:ken@a...]
Sent: Sunday, August 26, 2001 10:06 PM
To: ASP Web HowTo
Subject: [asp_web_howto] Re: Memory Leaks
ASP is *supposed* to have it's own garbage collection. However, it is always
good programming practice to clean up after yourself explicitly.
That said, why redirect? I usually have something like this:
<%
Function fncWhatever( _
)
On Error Resume Next
Const Proc = "fncWhatever"
...
If Err.Number <> 0 then
Call subErrorHandler(Err.Number, Proc, Err.Description)
End If
End Function ' fncWhatever
Sub subErrorHandler( _
ByVal strErrNum, _
ByVal strErrSource, _
ByVal strErrDescrip _
)
' Clear existing Response Buffer
Response.Clear
Call subWritePageHeading()
Call subWritePageBody()
With Response
.Write("<p>An error occured:<br>" & vbCrLf)
.Write("Err Number: " & strErrNum<br>" & vbCrLf)
.Write("Err Source: " & strErrSource<br>" & VbCrLf)
.Write("</p>" & vbCrLf)
End With
Call subWritePageFooter()
Response.Flush
Response.End
End Sub ' subErrorHandler
%>
Of course, subErrorHandler would be in an include file that you just include
on every page...
Cheers
Ken
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: <rg1@h...>
To: "ASP Web HowTo" <asp_web_howto@p...>
Sent: Friday, August 24, 2001 4:54 PM
Subject: [asp_web_howto] Memory Leaks
: Hi.
:
: I have a question regarding memory leaks.
:
: If I have Page1.asp that sets a reference to Object1, then Page1.asp
: encounters an error which will redirect to another page, thus bypassing
: the statement in Page1.asp to "Set Object1 = Nothing", will this cause a
: memory leak?
:
: I could, before redirecting, use a "subDispose(ObjToDispose)" for each
: reference set, but wondered if this was necessary.
:
: TIA.
:
: Rita
Message #6 by Rita Greenberg <rg1@h...> on Mon, 27 Aug 2001 12:43:21 -0700
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Thanks Kyle, for the explanation.
-----Original Message-----
From: Kyle Burns [mailto:kburns@c...]
Sent: Monday, August 27, 2001 11:15 AM
To: ASP Web HowTo
Subject: [asp_web_howto] Re: Memory Leaks
In many cases (should be always but doesn't work that way), the err object
is cleared when moving from proc to proc. You're better off persisting the
information into arguments of your error handler.
=================================
Kyle M. Burns, MCSD
ECommerce Technology Manager
Centra Credit Union
kburns@c...
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