webreq.getresponse exceptions

28 Oct 2006 12:30 PM

cj

VB 2003
I have a programs that accepts TCPIP requests and processes them. A
thread is created to handle each TCPIP connection. Part of handling the
request is involves making a webrequest.

webReq = Net.HttpWebRequest.Create(URL)
webReq.Timeout = 60000
webResp = webReq.GetResponse

This has been working fine for 6 months or more handling maybe 50
simultaneous requests but now the traffic has picked up substantially.
It might be handling 150 requests simultaneously. I'm beginning to get
exceptions thrown making the web request. I get either of these

The operation has timed-out.
The underlying connection was closed: The request was canceled.

The operation has timed-out exception is probably because it went over 1
minute and I have to have some sort of timeout because the TCPIP request
I got initially is waiting on it's reply and will not wait for long.

I don't know if the second exception is something I can do anything
about or if it is web server related. Any ideas?

30 Oct 2006 6:20 AM

Kevin Yu [MSFT]

Hi cj,

Based on the code snippet you have provided, I didn't see the code that
you're closing the underlying connection. Usually, people forget that the
underlying connection created by the request is not freed up,unless you
call Close() on the response. So, you hit the connection limit, and no more
webrequests will go through. Please call Response.Close() to close it when
it is used.

You can check the following link for more information.

http://blogs.msdn.com/feroze_daud/archive/2004/01/21/61400.aspx

If this still doesn't help, you may be facing a performance issue for your
ASP.NET app. Please check the following KB article for how to do
performance tuning on this issue.

http://support.microsoft.com/kb/821268/en-us

Kevin Yu
Microsoft Online Community Support

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30 Oct 2006 2:09 PM

cj

Kevin,

Yes, I close the connection. I only wanted to show the command I used
to contact the server.

Also I'm told the server I'm contacting has no set limit on it's
connections.

My program, this one we are talking about, is not ASP.NET. I guess you
know that. It is just a Windows program. I believe the web server is
running ASP.NET code and that could be the problem but I didn't write
that program. If you have suggestions on what the problem could be on
the web server side I can pass them on to the folks working on that program.

Here a small section of my actual code.

                         Try
                             Dim webReq As Net.HttpWebRequest
                             Dim webResp As Net.HttpWebResponse
                             Dim URL As String =
"http://192.168.168.142/validate/validate.aspx?" & _
                                                 iElement(3) & _
                                                 "&submit_by=R" & _
                                                 "&" & iElement(2)

                             webRespStr = ""

                             webReq = Net.HttpWebRequest.Create(URL)
                             webReq.Timeout = 15000
                             Try
                                 webResp = webReq.GetResponse
                             Catch ex As Exception
                                 LoopErrMsg += (deleted extra stuff here
for this email)
                             End Try

                             webResp.Close()

                             (deleted extra stuff here for this email)

                         Catch ex As Exception
                             LoopErrMsg += (deleted extra stuff here for
this email)
                         End Try

Kevin Yu [MSFT] wrote:
Show quoteHide quote

> Hi cj,
>
> Based on the code snippet you have provided, I didn't see the code that
> you're closing the underlying connection. Usually, people forget that the
> underlying connection created by the request is not freed up,unless you
> call Close() on the response. So, you hit the connection limit, and no more
> webrequests will go through. Please call Response.Close() to close it when
> it is used.
>
> You can check the following link for more information.
>
> http://blogs.msdn.com/feroze_daud/archive/2004/01/21/61400.aspx
>
> If this still doesn't help, you may be facing a performance issue for your
> ASP.NET app. Please check the following KB article for how to do
> performance tuning on this issue.
>
> http://support.microsoft.com/kb/821268/en-us
>
> Kevin Yu
> Microsoft Online Community Support
>
> ==================================================
> Get notification to my posts through email? Please refer to
> http://msdn.microsoft.com/subscriptions/managednewsgroups/default.aspx#notif
> ications.
> Note: The MSDN Managed Newsgroup support offering is for non-urgent issues
> where an initial response from the community or a Microsoft Support
> Engineer within 1 business day is acceptable. Please note that each follow
> up response may take approximately 2 business days as the support
> professional working with you may need further investigation to reach the
> most efficient resolution. The offering is not appropriate for situations
> that require urgent, real-time or phone-based interactions or complex
> project analysis and dump analysis issues. Issues of this nature are best
> handled working with a dedicated Microsoft Support Engineer by contacting
> Microsoft Customer Support Services (CSS) at
> http://msdn.microsoft.com/subscriptions/support/default.aspx.
> ==================================================
>
> (This posting is provided "AS IS", with no warranties, and confers no
> rights.)
>

30 Oct 2006 4:18 PM

cj

Ooops, I deleted a line by accident when removing extra junk from my
code to post. just before webresp.close() is the line

webrespstr = new io.streamreader(webresp.getresponsestream).readtoend

Sorry for the confusion.

cj wrote:
Show quoteHide quote

> Kevin,
>
> Yes, I close the connection. I only wanted to show the command I used
> to contact the server.
>
> Also I'm told the server I'm contacting has no set limit on it's
> connections.
>
> My program, this one we are talking about, is not ASP.NET. I guess you
> know that. It is just a Windows program. I believe the web server is
> running ASP.NET code and that could be the problem but I didn't write
> that program. If you have suggestions on what the problem could be on
> the web server side I can pass them on to the folks working on that
> program.
>
> Here a small section of my actual code.
>
>
>                         Try
>                             Dim webReq As Net.HttpWebRequest
>                             Dim webResp As Net.HttpWebResponse
>                             Dim URL As String =
> "http://192.168.168.142/validate/validate.aspx?" & _
>                                                 iElement(3) & _
>                                                 "&submit_by=R" & _
>                                                 "&" & iElement(2)
>
>                             webRespStr = ""
>
>
>                             webReq = Net.HttpWebRequest.Create(URL)
>                             webReq.Timeout = 15000
>                             Try
>                                 webResp = webReq.GetResponse
>                             Catch ex As Exception
>                                 LoopErrMsg += (deleted extra stuff here
> for this email)
>                             End Try
>
>                             webResp.Close()
>
>                             (deleted extra stuff here for this email)
>
>                         Catch ex As Exception
>                             LoopErrMsg += (deleted extra stuff here for
> this email)
>                         End Try
>
>
>
> Kevin Yu [MSFT] wrote:
>> Hi cj,
>>
>> Based on the code snippet you have provided, I didn't see the code
>> that you're closing the underlying connection. Usually, people forget
>> that the underlying connection created by the request is not freed
>> up,unless you call Close() on the response. So, you hit the connection
>> limit, and no more webrequests will go through. Please call
>> Response.Close() to close it when it is used.
>>
>> You can check the following link for more information.
>>
>> http://blogs.msdn.com/feroze_daud/archive/2004/01/21/61400.aspx
>>
>> If this still doesn't help, you may be facing a performance issue for
>> your ASP.NET app. Please check the following KB article for how to do
>> performance tuning on this issue.
>>
>> http://support.microsoft.com/kb/821268/en-us
>>
>> Kevin Yu
>> Microsoft Online Community Support
>>
>> ==================================================
>> Get notification to my posts through email? Please refer to
>> http://msdn.microsoft.com/subscriptions/managednewsgroups/default.aspx#notif
>>
>> ications.
>> Note: The MSDN Managed Newsgroup support offering is for non-urgent
>> issues where an initial response from the community or a Microsoft
>> Support Engineer within 1 business day is acceptable. Please note that
>> each follow up response may take approximately 2 business days as the
>> support professional working with you may need further investigation
>> to reach the most efficient resolution. The offering is not
>> appropriate for situations that require urgent, real-time or
>> phone-based interactions or complex project analysis and dump analysis
>> issues. Issues of this nature are best handled working with a
>> dedicated Microsoft Support Engineer by contacting Microsoft Customer
>> Support Services (CSS) at
>> http://msdn.microsoft.com/subscriptions/support/default.aspx.
>> ==================================================
>>
>> (This posting is provided "AS IS", with no warranties, and confers no
>> rights.)
>>

31 Oct 2006 8:10 AM

Kevin Yu [MSFT]

Hi cj,

Based on my experience, this has to be a server side issue. The web server
cannot support so many concurrent requests.

Although you have check that IIS doesn't have a limitation on connections,
the ASP.NET has some limitations set in the configuration file. I think you
have to tune the performance on the server according to the following KB
article

http://support.microsoft.com/kb/821268/en-us

This article is for ASP.NET 1.1. However, you can also use this in ASP.NET
2.0. The 2.0 machine.config file doesn't have the default value set. You
can add the keys and values manually.

Kevin Yu
Microsoft Online Community Support
==================================================

(This posting is provided "AS IS", with no warranties, and confers no
rights.)