Re: using System.Diagnostics.Stopwatch in an Button_Click Event: unusual results in specific test case - C# Discussion Boards

Re: using System.Diagnostics.Stopwatch in an Button_Click Event: unusual results in specific test case

25-Jul-13 1:55

Win 8/64 Visual Studio 2012 v.3, WinForms C#, FrameWork 4.5: no use of explicit threading in the project.

I've come to rely on using 'Stopwatch for a timer, and I am surprised to find, in a current project, a huge difference between what I observe, and what Stopwatch reports.

I have a very complex generic class, whose generic Types include other generic Type classes. I am able to create any number of instances of the outer class without a problem, and verify their contents.

Using Stopwatch to time the creation of the instances seems to give results consistent with what I observe. I'm not bothering, in this case, to do a "dry run" to pre-JIT.

Where what I observe really varies from what Stopwatch returns is: in the case where I loop through all the created instances in the outer class, and fill a StringBuilder with a complete kind of "report" on all the instances of the outer class, and all the various instances of the inner classes.

The inner classes have public Guid properties, set when their constructor is called (via 'private set).

If I create 10,000 instances of the outer class, and each of (in this case #2) of its inner classes have 10 objects each initialized as they are created. I end up with potentially 20k Guids, 100k each of the inner class contents. So, the resulting "report" (adding in tab characters, and other formatting) will come out to about 250k lines of text, containing about 4mb of characters.

From pressing the button that generates the "report" to seeing the report-TextBox filled, takes around thirty seconds, but Stopwatch is reporting the operation took 300~800 milliseconds.

Hypotheses:

1. there's something about using Stopwatch in the scope of a Button_Click EventHandler that leads to errors. Threading issue ? Doubtful, imho, since object creation seems to time okay.

2. there's something about using StringBuilder, and then converting to 'string, and setting the 'Text property of a TextBox that compromises Stopwatch. Wrapping TextBox refresh in 'SuspendLayout and 'ResumeLayout seem to have no appreciable effect.

Here's the code as stripped-down as possible to indicate how the report is being generated, and Stopwatch is being used:

sb.Clear();

// forcing GC, and waiting for finalizers to unqueue has no effect here
// GC.Collect();
// GC.WaitForPendingFinalizers();

// watch2 is an already declared System.Diagnostics.Stopwatch
// reset the watch, start it
watch2.Reset();
watch2.Start();

// fill the StringBuilder, 'sb
for (int i = 0; i < KVPList.Count; i++)
{
    // a whole-lot-of-looping-going-on
}

// tbReport is a TextBox with 'MultiLine = 'true
// tbReport.SuspendLayout();
    tbReport.Text = sb.ToString();
// tbReport.ResumeLayout();

watch2.Stop();

// a TextBox used to report results
tbEventReport.Text = "Report Displayed: Time(ms): " + watch2.Elapsed.Milliseconds

Appreciate any suggestions, or ideas; very high-precision timing is not really needed here.

thanks, Bill

~
“This isn't right; this isn't even wrong." Wolfgang Pauli, commenting on a physics paper submitted for a journal

Dave Kreskowiak25-Jul-13 2:15

Re: using System.Diagnostics.Stopwatch in an Button_Click Event: unusual results in specific test case

25-Jul-13 2:15

The problem isn't with Stopwatch at all. It's with sending 4MB of text to TextBox. Try opening a file that large in Notepad and you'll see the same result. It just takes forever for the TextBox to render something that large.

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Dave Kreskowiak

BillWoodruff25-Jul-13 22:48

Re: using System.Diagnostics.Stopwatch in an Button_Click Event: unusual results in specific test case

25-Jul-13 22:48

Dave,

I wonder what happened to you on this one: the general slowness of filling a standard WinForms TextBox control, or NotePad, with a large amount of Text is not relevant here at all.

How, I wonder, did such an inane response get three up-votes ?

The reason I am doing this stuff with showing a lot of text is related to software development; it has nothing to do with production mode, and some final software a user would interact with. I am examining the results of building a very large collection of a complex object, and that means I want to inspect the result in detail at run-time (much easier than setting a break-point in Visual Studio, and drilling down through little windows you have to scroll-in endlessly to reach item 899,233 out of 1 million).

The relevant issue is what I perceived as an inaccurate result using Stopwatch.

Alan's answer below points out the simple (and stupid) mistake I made in syntax.

Using Win 8/64, Visual Studio 2012 v.3, FrameWork 4.5, compiling to "AnyCPU," in Debug mode: using relatively old hardware (6420 CPU at 2.13mhz., 4gb. ram):

fyi: I can fill a TextBox with fifty-megabytes of text in around 33 seconds.

fyi: Using a RichTextBox I can fill it with fifty megabytes of text in under 3 seconds

fyi: converting a StringBuilder containing 50 mb. to a string: itself takes about 2 seconds.

fyi: NotePad ? I use UltraEdit, which can open a 50 mb. text file in under 3 seconds.

But, knowing someone with your skills can have an off-day, as I did; knowing you are imperfect, as I am: well, I feel less lonely Smile | :)

your friend, Bill

~
“This isn't right; this isn't even wrong." Wolfgang Pauli, commenting on a physics paper submitted for a journal

Dave Kreskowiak26-Jul-13 8:00

Re: using System.Diagnostics.Stopwatch in an Button_Click Event: unusual results in specific test case

26-Jul-13 8:00

My machine is a bit slower than yours. I can't do 50MB in 30 second.

But, you're correct. I lost my head had on this one.

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Dave Kreskowiak

BillWoodruff30-Jul-13 5:57

Re: using System.Diagnostics.Stopwatch in an Button_Click Event: unusual results in specific test case

30-Jul-13 5:57

A man who knows he lost his head, and gracefully admits it, is a man who has, not only a head, but a heart Smile | :)

appreciatively, Bill

~
“This isn't right; this isn't even wrong." Wolfgang Pauli, commenting on a physics paper submitted for a journal

Dave Kreskowiak30-Jul-13 6:46

Re: using System.Diagnostics.Stopwatch in an Button_Click Event: unusual results in specific test case

30-Jul-13 6:46

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Alan N25-Jul-13 5:27

Alan N

25-Jul-13 5:27

Ooh, that's difficult to spot. The mistake is subtle, easy to make and I'm sure I've done the same thing.

Stopwatch.Elapsed is a TimeSpan and TimeSpan.Milliseconds is just the millisecond component. If the measured value is less than 1 second then the result will be correct but either Stopwatch.Elapsed.TotalMilliseconds or Stopwatch.ElapsedMilliseconds would be what you really wanted.

Alan.

Re: using System.Diagnostics.Stopwatch in an Button_Click Event: unusual results in specific test case

BillWoodruff25-Jul-13 22:13

Paramerterized OleDB Query

25-Jul-13 22:13

Alan, you nailed it ! And, how gently you broke the news, thanks Smile | :)

I was relieved to search all my code for the last several years, and find not one instance where I had made the same mistake made here: but, not relieved enough to get over the chagrin of making such a stupid mistake now.

I owe you an elephant-ride in the jungle in northern-Thailand.

yours, Bill

~
“This isn't right; this isn't even wrong." Wolfgang Pauli, commenting on a physics paper submitted for a journal

gautamn199025-Jul-13 1:21

25-Jul-13 1:21

To suppress the warning CA2100 i am trying to create a parameterized query. By the following code.

string sheet_name=listBox_Select_a_sheet.SelectedItem.ToString();

OleDbCommand cmd = MyConnection.CreateCommand();

cmd.CommandText = "SELECT count(*) FROM [?]";

cmd.Parameters.AddWithValue("?", sheet_name);

cmd.ExecuteNonQuery();

The value of the ? is not replaced.

I have also tried the following

 OleDbCommand cmd = MyConnection.CreateCommand();

OleDbParameter para = new OleDbParameter("?", sheet_name);

cmd.Parameters.Add(para);

cmd.CommandText = "SELECT count(*) FROM [?]";

and

string strSql = "SELECT count(*) FROM [@Name]";
cmd.Parameters.AddWithValue("@Name", sheet_name);

My aim is to replace the ? with the parameter.

And one more doubt is can we use parameterized query to replace a table name?

Dave Kreskowiak25-Jul-13 2:17

25-Jul-13 2:17

Parameters do not work for table identifiers. They only work for columns or other identifiers that use data types, such as stored procedure parameters.

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gautamn199025-Jul-13 20:28

25-Jul-13 20:28

Thank you for your kind reply. That was very helpful. One more thing need to be cleared. How can we suppress the warning CA2100 : Microsoft.Security for the following code?

string sheet_name=listBox_Select_a_sheet.SelectedItem.ToString();
string strSql = "SELECT count(*) FROM sheet_name";
using (OleDbCommand cmd = new OleDbCommand(strSql, MyConnection))//CA2100 Warning:Microsoft.Security
{
   cmd.ExecuteNonQuery();
}

Dave Kreskowiak26-Jul-13 3:52

26-Jul-13 3:52

Turn off Code Analysis when you compile. It's not a compiler warning but a code analysis warning. This is to remind you that you should not use user input directly when building your SQL statement as a string.

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Dave Kreskowiak

gautamn199028-Jul-13 20:03

28-Jul-13 20:03

Thank you so much for your kind support. I have learned new things on parameterized OleDB Query. I hope to help help other in future.

PIEBALDconsult25-Jul-13 15:19

PIEBALDconsult

25-Jul-13 15:19

gautamn1990 wrote:
To suppress the warning CA2100

Never heard of it, never seen it. I do something like:

string strSql = System.String.Format ( "SELECT count(*) FROM [{0}]" ,sheet_name) ;

for table names there's really no substitute. Unsure | :~

gautamn199025-Jul-13 20:45

25-Jul-13 20:45

Thank you for your reply. I tried your concept. the name is getting replaced but during code analysis CA2100: Microsoft.Security: warning is still appearing. Sting sheet_name is value in obtained from users input by the following code.

string sheet_name=listBox_Select_a_sheet.SelectedItem.ToString();
string strSql = "SELECT count(*) FROM sheet_name";
using (OleDbCommand cmd = new OleDbCommand(strSql, MyConnection))//CA2100 Warning:Microsoft.Security
{
   cmd.ExecuteNonQuery();
}

How to supress the CA2100 Warning:MicroSoft.Security ?