I have an ASP.NET site (VB.NET) that I'm trying to clean up. When it was originally created it was written with no error handling, and I'm trying to add it in to improve the User Experience.
Try
If Not String.IsNullOrEmpty(strMfgName) And Not String.IsNullOrEmpty(strSortType) Then
If Integer.TryParse(Request.QueryString("CategoryID"), i) And String.IsNullOrEmpty(Request.QueryString("CategoryID"))
MyDataGrid.DataSource = ProductCategoryDB.GetMfgItems(strMfgName, strSortType, i)
Else
MyDataGrid.DataSource = ProductCategoryDB.GetMfgItems(strMfgName, strSortType)
End If
MyDataGrid.DataBind()
If CType(MyDataGrid.DataSource, DataSet).Tables("Data").Rows.Count > 0 Then
lblCatName.Text = CType(MyDataGrid.DataSource, DataSet).Tables("Data").Rows(0).Item("mfgName")
End If
If MyDataGrid.Items.Count < 2 Then
cboSortTypes.Visible = False
table_search.Visible = False
End If
If MyDataGrid.PageCount < 2 Then
MyDataGrid.PagerStyle.Visible = False
End If
Else
lblCatName.Text &= "<br /><span style=""fontf-size: 12px;"">There are no items for this manufacturer</span>"
MyDataGrid.Visible = False
table_search.Visible = False
End If
Catch
lblCatName.Text &= "<br /><span style=""font-size: 12px;"">There are no items for this manufacturer</span>"
MyDataGrid.Visible = False
table_search.Visible = False
End Try
Now, this is trying to avoid generating a 500 error by catching exceptions. There can be three items on the query string, but only two matter here. In my test environment and in Visual Studio when I run this site, it doesn't matter if that item is on the query string. In production, it does matter. If that third item isn't present (SubCategoryID) on the query string, then the "There are no items for this manufacturer" displays instead of the data from the database.
In the two different environments I am seeing two different code execution paths, despite the same URLs and the same code base.
The site is running on Server 2003 with IIS 6.
Thoughts?
EDIT:
In response to the answer below, I doubt it's a connection error (though I see what you're getting to), as when I add the SubCategoryID to the query string, the site works correctly (displaying data from the database).
Also, if please let me know if you have any suggestions for how to test this scenario, without deploying the code back to production (it's been rolled back).
I think you should try to print out the exception details in your catch block to see what the problem is. It could anything for example a connection error to your database.
The error could be anything, and you should definitely consider printing this out or logging it somewhere, rather than making the assumption that there's no data. You're also outputting the same error message to the UI for two different code paths, which makes things harder to debug, especially without knowing if an exception occurred, and if so, what it was.
Generally, it's also better not to have a catch for all exceptions in cases like this, especially without logging the error. Instead, you should catch specific exceptions and handle these appropriately, and any real exceptions can get passed up the stack, ideally to a global error handler which can log it and/or send out some kind of error notification.
I discovered the reason yesterday. In short it was because when I copied my files from my computer into my dev-test environment, I missed a file, which ironically caused it to work, rather than not. So in the end it would have functioned the same in both environments.
Related
I'm using Zeos and SQLite3 DB in Delphi
ZQuery2.Close;
ZQuery2.SQL.Clear;
ZQuery2.SQL.Add('SELECT * FROM users WHERE un = ' + QuotedStr( UserName ) );
ZQuery2.Open;
OutputDebugString(PWideChar( ZQuery2.FieldDefList.CommaText )); // log : id,un,pw
OutputDebugString(PWideChar(ZQuery2.FieldByName('pw').AsString)); //causes error sometimes
the code is working but sometimes I get the following error message
Exception class EDatabaseError with message 'ZQuery2:Field'pw' not found'.
This is odd because a field of a dataset shouldn't just disappear while the app is in the middle of running, especially if other fields are still operating normally. So, I would suspect something like a memory overwrite being the cause.
Memory overwrites usually happen when something is written to the wrong place in memory, overwriting what is there, usually because of an incorrect pointer value or a so-called "buffer overrun" where the writing operation carries on beyond where is should stop. Usually, the pointer value is so wildly wrong that the OS can detect it and raise an AV, but sometimes it is less obvious.
Delphi's memory manager has a 'full debug mode' which adds special checks for this condition, see here.
I suggest you enable full debug mode as per the linked document and wait for the exception to occur.
I have a classic ASP CRM that was built by a third party company. Currently, I have access to the source code and am able to make any changes required.
Randomly throughout the day, usually after some prolonged usage by users, most of my pages start getting an Out of Memory error.
The way that the application is built, is all the pages and scripts pull core functions from a Global.asp file. In that file are embeds to other global files as well, but the error presented shows
Out Of Memory
WhateverScriptYouTriedToRun.asp Line 0
Line 0 is the include for the global.asp file. Once the error occurs, after an unspecified amount of time the error occurence subsides for some time but then begins to reoccur again. With how the application is written, and the functions it uses, and the "diagnostics" I've already done - it seems to be a common used function that is withholding data such as recordset or something of that nature and then not releasing it properly. Other users then try to use the same function and eventually it just fills up causing the error. The only way for me to effectively clear the error is to actually restart IIS, Recycle the App Pool, and Restart the SQL Server Services.
Needless to say, myself and my users are getting annoyed....
I can't pinpoint the error due to the actual error message presented being Line 0 - but from there I have no idea where in the 20K lines of code it could be hanging up. Any thoughts or ideas on how to isolate or at least point me in the right direction to begin clearing this up? Is there a way for me to increase "memory" size for VBScript? I know there is a limitation but is it set at say...512K and you can increase it to 1GB?
Here are things I have tried:
Removing SQL Inline statements into Views
Going through several hundred scripts and ensuring that every OpenConnection & OpenRecordSet is followed by an appropriate Close.
Going through the Global File and commenting out any large SQL statements such as ApplicationLog (A function that writes the executed query into a table).
Some smaller script edits.
Common Memory Leak
You say you are closing all recordsets and connections which is good.
But are you deleting objects?
For example:
Set adoCon = new
Set rsCommon = new
'Do query stuff
'You do this:
rsCommon.close
adocon.close
'But do you do this?
Set adoCon = nothing
Set rsCommon = nothing
No garbage collection in classic ASP, so any objects not destroyed will remain in memory.
Also, ensure your closes/nothings are run in every branch. For example:
adocon.open
rscommon.open etc
'Sql query
myData = rscommon("condition")
if(myData) then
response.write("ok")
else
response.redirect("error.asp")
end if
'close
rsCommon.close
adocon.close
Set adoCon = nothing
Set rsCommon = nothing
Nothing is closed/destroyed before the redirect so it will only empty memory some of the time as not all branches of logic lead to the proper memory clearance.
Better Design
Also unfortunately it sounds like the website wasn't designed well. I always structure my classic ASP as:
<%
Option Explicit
'Declare all vars
Dim this
Dim that
'Open connections
Set adoCon...
adocon.open()
'Fetch required data
rscommon.open strSQL, adoCon
this = rsCommon.getRows()
rsCommon.close
'Fetch something else
rscommon.open strSQL, adoCon
that = rsCommon.getRows()
rsCommon.close
'Close connections and drop objects
adoCon.close
set adoCon = nothing
set rscommon = nothing
'Process redirects
if(condition) then
response.redirect(url)
end if
%>
<html>
<body>
<%
'Use data
for(i = 0 to ubound(this,2)
response.write(this(0, i) & " " & this(1, i) & "<br />")
next
%>
</body>
</html>
Hope some of this helped.
Have you looked at using a memory monitoring tool to see how much memory fragmentation is happening? My guess at a possible cause is that some object of a size is trying to be created but there isn't enough room in the memory to store it as one contiguous chunk. Imagine needing room to store an object that would take 100 MB and while there may be several hundred megabytes free, the largest contiguous chunk is 90MB then this doesn't fit.
Debug Diagnostic Tool v1.1 would be a tool where Bernard's articles may help in understanding how to use the tool.
Another thought is the question of how much string concatenation is there in the code? I remember where I used to work had problems with doing a lot of string concatenation operations that sucked up memory that may be another idea to consider.
Yeah, I could see some shock at that kind of number the first few times you see it but then if you understand what the code is doing it may make sense for why so much space gets reserved right off the bat at times.
I haven't used that debug tool specifically but I did have a tool that took a snapshot of memory when pages were hung so I couldn't tell if there was a performance impact of the tool or not. Course in my case I used a similar tool in 2004 so it has been a few years since I've had to research this kind of issue.
Just going to throw this in here, but this problem has taken a long time to solve. Here's a breakdown of what we did:
We took all the inline SQL and made SQL Views, every SELECT statement is now handled with a VIEW first.
I took every single SQL INSERT and UPDATE (as much as I could without breaking the system) and put them into Stored Procedures.
#2 was the one item that really made the biggest difference
Went through several thousand scripts, and ensured that variables were properly disposed of, and all the DB Open Connections were followed correctly with a Close Connection and same with Open/Close RecordSet.
One of the slow killers was doing something like:
ID = Request.QueryString("ID)
at the top of the page. Before redirecting, or closing a page, there is always a:
Set ID = Nothing
or the complete removal of the inference.
I am running a simple query to get data out of my database & display them. I'm getting an error that says Response Buffer Limit Exceeded.
Error is : Response object error 'ASP 0251 : 80004005'
Response Buffer Limit Exceeded
/abc/test_maintenanceDetail.asp, line 0
Execution of the ASP page caused the Response Buffer to exceed its configured limit.
I have also tried Response.flush in my loop and also use response.buffer = false in my top of the page, but still I am not getting any data.
My database contains 5600 records for that, Please give me some steps or code to solve the issue.
I know this is way late, but for anyone else who encounters this problem: If you are using a loop of some kind (in my case, a Do-While) to display the data, make sure that you are moving to the next record (in my case, a rs.MoveNext).
Here is what a Microsoft support page says about this:
https://support.microsoft.com/en-us/help/944886/error-message-when-you-use-the-response-binarywrite-method-in-iis-6-an.
But it’s easier in the GUI:
In Internet Information Services (IIS) Manager, click on ASP.
Change Behavior > Limits Properties > Response Buffering Limit from 4 MB to 64 MB.
Apply and restart.
The reason this is happening is because buffering is turned on by default, and IIS 6 cannot handle the large response.
In Classic ASP, at the top of your page, after <%#Language="VBScript"%> add:
<%Response.Buffer = False%>
In ASP.NET, you would add Buffer="False" to your Page directive.
For example:
<%#Page Language="C#" Buffer="False"%>
I faced the same kind of issue, my IIS version is 8.5. Increased the Response Buffering Limit under the ASP -> Limit Properties solved the issue.
In IIS 8.5, select your project, you can see the options in the right hand side. In that under the IIS, you can see the ASP option.
In the option window increase the Response Buffering Limit to 40194304 (approximately 40 MB) .
Navigate away from the option, in the right hand side top you can see the Actions menu, Select Apply. It solved my problem.
If you are not allowed to change the buffer limit at the server level, you will need to use the <%Response.Buffer = False%> method.
HOWEVER, if you are still getting this error and have a large table on the page, the culprit may be table itself. By design, some versions of Internet Explorer will buffer the entire content between before it is rendered to the page. So even if you are telling the page to not buffer the content, the table element may be buffered and causing this error.
Some alternate solutions may be to paginate the table results, but if you must display the entire table and it has thousands of rows, throw this line of code in the middle of the table generation loop: <% Response.Flush %>. For speed considerations, you may also want to consider adding a basic counter so that the flush only happens every 25 or 100 lines or so.
Drawbacks of not buffering the output:
slowdown of overall page load
tables and columns will adjust their widths as content is populated (table appears to wiggle)
Users will be able to click on links and interact with the page before it is fully loaded. So if you have some javascript at the bottom of the page, you may want to move it to the top to ensure it is loaded before some of your faster moving users click on things.
See this KB article for more information http://support.microsoft.com/kb/925764
Hope that helps.
Thank you so much!
<%Response.Buffer = False%> worked like a charm!
My asp/HTML table that was returning a blank page at about 2700 records. The following debugging lines helped expose the buffering problem: I replace the Do While loop as follows and played with my limit numbers to see what was happening:
Replace
Do While not rs.EOF
'etc .... your block of code that writes the table rows
rs.moveNext
Loop
with
Do While reccount < 2500
if rs.EOF then recount = 2501
'etc .... your block of code that writes the table rows
rs.moveNext
Loop
response.write "recount = " & recount
raise or lower the 2500 and 2501 to see if it is a buffer problem. for my record set, I could see that the blank page return, blank table, was happening at about 2700 records, good luck to all and thank you again for solving this problem! Such a simple great solution!
You can increase the limit as follows:
Stop IIS.
Locate the file %WinDir%\System32\Inetsrv\Metabase.xml
Modify the AspBufferingLimit value. The default value is 4194304, which is about 4 MB.
Changing it to 20MB (20971520).
Restart IIS.
One other answer to the same error message (this just fixed my problem) is that the System drive was low on disk space. Meaning about 700kb free. Deleting a lot of unused stuff on this really old server and then restarting IIS and the website (probably only IIS was necessary) cause the problem to disappear for me.
I'm sure the other answers are more useful for most people, but for a quick fix, just make sure that the System drive has some free space.
I rectified the error 'ASP 0251 : 80004005' Response Buffer Limit as follow:
To increase the buffering limit in IIS 6, follow these steps:
Click Start, click Run, type cmd, and then click OK.
Type the following command, and then press ENTER:
cd /d %systemdrive%\inetpub\adminscripts
Type the following command, and then press ENTER:
cscript.exe adsutil.vbs SET w3svc/aspbufferinglimit LimitSize
Note LimitSize represents the buffering limit size in bytes. For example, the number 67108864 sets the buffering limit size to 64 MB.
To confirm that the buffer limit is set correctly, follow these steps:
Click Start, click Run, type cmd, and then click OK.
Type the following command, and then press ENTER:
cd /d %systemdrive%\inetpub\adminscripts
Type the following command, and then press ENTER:
cscript.exe adsutil.vbs GET w3svc/aspbufferinglimit
refers to https://support.microsoft.com/en-us/kb/944886
If you are looking for the reason and don't want to fight the system settings, these are two major situations I faced:
You may have an infinite loop without next or recordest.movenext
Your text data is very large but you think it is not! The common reason for this situation is to copy-paste an Image from Microsoft word directly into the editor and so the server translates the image to data objects and saves it in your text field. This can easily occupies the database resources and causes buffer problem when you call the data again.
In my case i just have writing this line before rs.Open .....
Response.flush
rs.Open query, conn
It can be due to CursorTypeEnum also. My scenario was the initial value equal to CursorTypeEnum.adOpenStatic 3.
After changed to default, CursorTypeEnum.adOpenForwardOnly 0, it backs to normal.
I am pretty new to LINQ and having a issue with what seems to be irregular content caching. The website in question has 6 content areas of different subjects now on the odd occasion the content just blanks out to nothing or has the same content for all 6 areas. It will clear up this issue by itself over time or the only other way to fix it is to recycle the app pool :(
Have tried using
DBLocal.Refresh(System.Data.Linq.RefreshMode.OverwriteCurrentValues, ret)
but this caused similar problems.
Has anyone else come across this problem as I cannot seem to find anything about it online
Thanks
Clinton
ADDED CODE:
Dim discussionDetails As Model.Discussion = Services.Discussion.getById(discussionId)
Public Function getById(ByVal discussionId As Integer) As Model.Discussion
Dim _discussion As Model.Discussion = DBLocal.Discussions.SingleOrDefault(Function(p) p.DiscussionId.Equals(discussionId))
Return _discussion
End Function
You haven't shown us the lifecycle of the DBLocal instance. It should be per-request at longest, and per-unitofwork ideally.
You haven't shown us the code that assigns the discussion to a content area, nor the code that calls this method (how frequently is it called and where does that code get Ids from?)
Consider these cases.
SingleOrDefault returns null, if there is no matching instance.
SingleOrDefault throws if there is more than one matching instance.
When I call this function, everything works, as long as I don't try to recursively call the function again. In other words if I uncomment the line:
GetChilds rsData("AcctID"), intLevel + 1
Then the function breaks.
<%
Function GetChilds(ParentID, intLevel)
Set rsData= Server.CreateObject("ADODB.Recordset")
sSQL = "SELECT AcctID, ParentID FROM Accounts WHERE ParentID='" & ParentID &"'"
rsData.Open sSQL, conDB, adOpenKeyset, adLockOptimistic
If IsRSEmpty(rsData) Then
Response.Write("Empty")
Else
Do Until rsData.EOF
Response.Write rsData("AcctID") & "<br />"
'GetChilds rsData("AcctID"), intLevel + 1
rsData.MoveNext
Loop
End If
rsData.close: set rsData = nothing
End Function
Call GetChilds(1,0)
%>
*Edited after feedback
Thanks everyone,
Other than the usual error:
Error Type: (0x80020009) Exception occurred.
I wasn't sure what was causing the problems. I understand that is probably due to a couple of factors.
Not closing the connection and attempting to re-open the same connection.
To many concurrent connections to the database.
The database content is as follows:
AcctID | ParentID
1 Null
2 1
3 1
4 2
5 2
6 3
7 4
The idea is so that I can have a Master Account with Child Accounts, and those Child Accounts can have Child Accounts of their Own. Eventually there will be Another Master Account with a ParentID of Null that will have childs of its own. With that in mind, am I going about this the correct way?
Thanks for the quick responses.
Thanks everyone,
Other than the usual error:
Error Type: (0x80020009) Exception
occurred.
I wasn't sure what was causing the problems. I understand that is probably due to a couple of factors.
Not closing the connection and attempting to re-open the same connection.
To many concurrent connections to the database.
The database content is as follows:
AcctID | ParentID
1 Null
2 1
3 1
4 2
5 2
6 3
7 4
The idea is so that I can have a Master Account with Child Accounts, and those Child Accounts can have Child Accounts of their Own. Eventually there will be Another Master Account with a ParentID of Null that will have childs of its own. With that in mind, am I going about this the correct way?
Thanks for the quick responses.
Look like it fails because your connection is still busy serving the RecordSet from the previous call.
One option is to use a fresh connection for each call. The danger there is that you'll quickly run out of connections if you recurse too many times.
Another option is to read the contents of each RecordSet into a disconnected collection: (Dictionary, Array, etc) so you can close the connection right away. Then iterate over the disconnected collection.
If you're using SQL Server 2005 or later there's an even better option. You can use a CTE (common table expression) to write a recursive sql query. Then you can move everything to the database and you only need to execute one query.
Some other notes:
ID fields are normally ints, so you shouldn't encase them in ' characters in the sql string.
Finally, this code is probably okay because I doubt the user is allowed to input an id number directly. However, the dynamic sql technique used is very dangerous and should generally be avoided. Use query parameters instead to prevent sql injection.
I'm not too worried about not using intLevel for anything. Looking at the code this is obviously an early version, and intLevel can be used later to determine something like indentation or the class name used when styling an element.
Running out of SQL Connections?
You are dealing with so many layers there (Response.Write for the client, the ASP for the server, and the database) that its not surprising that there are problems.
Perhaps you can post some details about the error?
hard to tell without more description of how it breaks, but you are not using intLevel for anything.
How does it break?
My guess is that after a certain number of recursions you're probably getting a Stack Overflow (ironic) because you're not allocating too many RecordSets.
In each call you open a new connection to the database and you don't close it before opening a new one.
Not that this is actually a solution to the recursion issue, but it might be better for you to work out an SQL statement that returns all the information in a hierarchical format, rather than making recursive calls to your database.
Come to think of it though, it may be because you have too many concurrent db connections. You continually open, but aren't going to start closing until your pulling out of your recursive loop.
try declaring the variables as local using a DIM statement within the function definition:
Function GetChilds(ParentID, intLevel)
Dim rsData, sSQL
Set ...
Edit: Ok, I try to be more explicit.
My understanding is that since rsData is not declared by DIM, it is not a local variable, but a global var. Therefore, if you loop through the WHILE statement, you reach the .Eof of the inner-most rsData recordset. You return from the recursive function call, and the next step is again a rsData.MoveNext, which fails.
Please correct me if rsData is indeed local.
If you need recursion such as this I would personally put the recursion into a stored procedure and handle that processing on the database side in order to avoid opening multiple connections. If you are using mssql2005 look into something called Common Table Expressions (CTE), they make recursion easy. There are other ways to implement recursion with other RDBMS's.
Based on the sugestions I will atempt to move the query into a CTE (common table expression) when I find a good tutorial on how to do that. For now and as a quick and dirty fix, I have changed the code as follows:
Function GetChilds(ParentID, intLevel)
'Open my Database Connection and Query the current Parent ID
Set rsData= Server.CreateObject("ADODB.Recordset")
sSQL = "SELECT AcctID, ParentID FROM Accounts WHERE ParentID='" & ParentID &"'"
rsData.Open sSQL, conDB, adOpenKeyset, adLockOptimistic
'If the Record Set is not empty continue
If Not IsRSEmpty(rsData) Then
Dim myAccts()
ReDim myAccts(rsData.RecordCount)
Dim i
i = 0
Do Until rsData.EOF
Response.Write "Account ID: " & rsData("AcctID") & " ParentID: " & rsData("ParentID") & "<br />"
'Add the Childs of the current Parent ID to an array.
myAccts(i) = rsData("AcctID")
i = i + 1
rsData.MoveNext
Loop
'Close the SQL connection and get it ready for reopen. (I know not the best way but hey I am just learning this stuff)
rsData.close: set rsData = nothing
'For each Child found in the previous query, now lets get their childs.
For i = 0 To UBound(myAccts)
Call GetChilds(myAccts(i), intLevel + 1)
Next
End If
End Function
Call GetChilds(1,0)
I have working code with the same scenario.
I use a clientside cursor
...
rsData.CursorLocation = adUseClient
rsData.Open sSQL, conDB, adOpenKeyset, adLockOptimistic
rsData.ActiveConnectcion = Nothing
...
as pointed out in other responses, this is not very efficient, I use it only in an admin interface where the code is called infrequently and speed is not as critical.
I would not use such a recursive process in a regular web page.
Either rework the code to get all data in one call from the database, or make the call once and save it to a local array and save the array in an application variable.