Write Functions In Microsoft.NET (VB) To Avoid Memory Leaks?
May 8, 2012
What is the best way to write functions in Microsoft.NET (VB) to avoid memory leaks. I have always followed this style:
Public Sub TestMemoryLeak()
Dim testCon As SqlConnection
Try
[code].....
Here the connection reference is created before the TRY clause and is initialised after the TRY clause. I believe the connection is always closed and dereferenced even if an exception is thrown. Is this good practice? I see a lot of code that creates references and dereferences in the TRY clause, but this would mean that the memory is not correctly handled if an exception is thrown. Some developers say they don't like to clean up in the finally clause.
I have a BackgroundWorker object that I instantiated to perform a DB process on a background thread ansynchronously. I have event handlers for DoWork and RunWorkerCompleted. I can tell that the BackgroundWorker is disposing of itself because I added a message box into the Disposed event handler.Is it necessary to detach the event handlers to ensure that the memory is cleaned up and that there are not memory leaks?
I've noticed that every time I start a new thread in my program, the memory usage jumps about 1000k and it never goes back down. I have ensured that the thread is no longer running, and only one instance of my worker thread is ever running at a time. I am using ThreadPool.QueueUserWorkItem and ASyncOperation to get stuff done. The program starts using a Sub Main in a module that uses STAThread; I read that using STAThread instead of MTAThread makes it impossible for the Garbage Collector to get in and consider objects for garbage collection. However, when I change the STAThread to an MTAThread, the WebBrowser control in my frmMain cannot be instantiated.
I get this exception:
Code: An unhandled exception of type 'System.Threading.ThreadStateException' occurred in System.Windows.Forms.dll
Additional information: ActiveX control '8856f961-340a-11d0-a96b-00c04fd705a2' cannot be instantiated because the current thread is not in a single-threaded apartment. I do threading with the WebBrowser control, so will using MTAThread fix my problem? If so, how should I partition my code so that the WebBrowser control won't be affected by the above exception? I call the thread repeatedly with a timer (although only one instance ever runs at a time), and my program's memory usage starts at about 5000k and can jump to 300,000k+ depending on many times the thread needs to be called.
I've been using a simple mouse hook and some accessiblity api stuff to retreive caption under mouse (ObjectFromPoint) and accessibility api for events (ObjectFromEvent).It seems like there is memory leaks with unmanaged callbacks.With the global mouse hook it seems there is 4 - 8k of ram added every time the mouse is just moved even though I only monitor mousedown and mouseup with:
Private Const WM_LBUTTONDOWN As UInteger = &H201 Private Const WM_LBUTTONUP As UInteger = &H202 Private Const WM_MBUTTONDOWN As UInteger = &H207
[code]....
And with accessibility it seems there is also memory issues with my code. Is this to do with delegates?I only managed to find one mention on the mouse hook issues which led me in to a dead end.A long shot and maybe not even needed but I was wondering, if these mem leaks can't be stopped, would it free up the memory if I used threads which could be exited and new ones started eg.mem usage 3000k of which 1000k is leaked mem (for round figures) I exit global mouse hook thread and start a new m-hook thread.would this free up the memory? If so, how would i do this, not use threading before.
I have attempted to understand the behind-the-scenes stuff for Events several times. I must have read at least a dozen articles but there is still some ambiguity in my head.
Im getting a problem with one of my programs I have made in visual basic.NET where it gives me a memory error when i debug the program in the IDE. the exact error is this: "Attempted to read or write protected memory. This is often an indication that other memory is corrupt". My program basically has a few forms with text fields on that get their text values from an access database on the same hard drive. Im wondering if im doing something wrong because my program just seems to eat up memory whenever it does anything. For example I have one form that has a combobox on it and when you change the drop down list selection it retreives a few strings from the database and puts them into the relevant text boxes, if you keep changing the selection then the memory usage (in task manager) just keeps going up and up. occasionally I get the error mentioned above when debugging but in my built version of the program it throws an exception everytime the memory usage gets past 49K.
Also I noticed when debugging in the "immediate window" frame I get the following message often:A first chance exception of type 'System. Invalid OperationException' occurred in System.Data.dll...Do I need to somehow be "releasing" the memory that is used to gather data once it becomes redundant?
Attempted to read or write protected memory. This is often an indication that other memory is corrupt. Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
QuoteSystem.AccessViolationException was unhandled Message="Attempted to read or write protected memory. This is often an indication that other memory is corrupt." Source="System.Windows.Forms"
Im designing a web browser and i continue to receive this error after going to about 3 websites it crashes with that error.
I cannot use Visual Basic 2008 at all. When I go to "new project" and choose "Windows Form Application" I get this error.I have tried multiple uninstall/reinstall with no result.A microsoft reply to this suggested that I needed: " .NET Framework 2.0 Service Pack 1 " I checked, and I did not have the .netframework 2.0 service Pack 1. When I tried to download and install the above from Microsoft.com, the istaller said that "it was not allowsed" and I was not able to install the service pack 1.
I tried Uninstalling net framework 3.5, 3.0, 2.0 and then reinstalling .netframework 2.0 sevice pack 1; then reinstalling Visual basic 2008 express edition. At the reinstall of Visual basic 2008, .netframework 2.0 sevice pack 1 is unistalled by .net framework service pack 2.When I check the foruims for simiar problems, the formus are mostly for Visual basic 5.0, or other programs that I do not have.
Here is the programs I have installed:
Operating system: Windows XP Microsoft .net framework 1.1 Microsoft .NET framwork 1.1 Hotfix(KB928366) Microsoft .Net Framework 2.0 Service Pack 2
[code]....
All the security updates and hotfixes for Widows XP.
I have two forms, Form1 and Form2. Form2 has a button to show OpenFileDialog. I call Form2 from Form1 by a button. My startUp Form is Form1. When i start debugging, i press my Form1's button to show my Form2, it shows, but when i click On Form2's Button to show OpenFileDialog it is giving me exception that
"Attempted to read or write protected memory. This is often an indication that other memory is corrupt."
When i set my startup Form to Form2 and click Form2's Button to show OpenFileDialog then it shows!
I'm trying to find a memory leak in my application and I want to know if I must (or should) call EndInvoke in case of a timeout. I'm calling a external system and I must have a way to stop waiting if execution is too long:
Dim ar As IAsyncResult Try ar = deleg.BeginInvoke(Nothing, New Object) If Not ar.AsyncWaitHandle.WaitOne(getTimeout, False) Then
I'm searching for a solution to resize image(jpg) being passed in from an array in Picturebox Control on .NETCF 2.0 in VB.NET without resorting to using the opennetcf library, is it possible?
i am a beginner in vb.net programming...started a project in it.Below is the breif project description.The application is to ensure the integrity of the files.Following are the majors things that i have to implement
1. To browse the files from the disk on runtime.initially i am just taking the database files so it's basically to connect with the MS access db files.
2.To apply the different hash and encryption algos on the file.
3.To store the results on the hard disk back.
4. To calulate the performance of each algo using some performance matrix.(TIME,MEMORY USAGE etc)
Now i am having problem in two things.First in runtime connectivity with MS access batabase..and secondly and the main problem is that i could'nt find any appropriate builtin function to calulate the processing TIME and the MEMORY usage.
I am getting the following error: "Attempted to read or write protected memory. This is often an indication that other memory is corrupt". i am using interop service.
I am unsure how to write in message box functions for a pop up window. I need OK and Cancel buttons to display with my message box. The Ok button needs to close the message box and the Cancel button to close the entire program. Here is what I have so far
Public Class Form1 Public scoreA, scoreB As Single Private Sub txtboxa_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtboxa.TextChanged scoreA = txtboxa.Text
I am trying to convert a VB.NET project to C#. I am conveting all the forms and classes as required, but I don't know where I need to write the events from ApplicationEvents.vb (I believe its autoGenerated from Properties) Here is the code in my ApplicationEvent.vb file:
I have a program and the program works fine. The only thing is that I want to shorten it up and stop using the same code over and over. I use the same redudant code through out the code. I want to write some functions in order to stop from having to use the same code over and over in my program. I wanted to know if someone could help me with functions: Here is part of my code below.
need to know exactly how does the API functions Read/Whrite Process works. I'm so confused while working. I know that I have to work using something like sectors. But I don't know how. Can someone give me an example. I dont know hoe to do it. for an example, for you to give me. Create a basic programa with a button and a textbox the button searchs what is in the textbox in a process memory. Search the title of a program for example.
how to write to memory some data and then read it back?
If i have 1GB free of memory i would like to write 100MB to memory some data and then read it back, i searched net for some documentations but cant find nothing, only writing to other process and some stupidities!
This is my 50th attempt to read the memory and probably my last attempt if I don't succeed now T_T I've been trying to write a class that reads from the memory, simply by creating wrappers around the Win32 APIs but I just can't get it to work.
This is how I currently am trying to read the memory from calc.exe:
Public Function ReadMemory(ByVal hProcess As IntPtr, ByVal lpBaseAddress As IntPtr, ByVal nSize As Integer, ByVal lpNumberOfBytesRead As Integer) As String Dim tmpBuff As Single = 0
If you match two same colours or pictures, you get some points. There should be nine pairs of hidden pictures/colours but shows up when clicked but should not in the same order or line. There has to be a count down timer as well.
I have a problem Hi i readtext vb.net, but I can also use VB6 does not work any error in writetext stops but does not write ..
WriteText Code: Public Sub WriteText(ByVal lngAddress As Integer, ByVal strText As String) Dim hWnd As Object, processHandle As Object, processId As Integer
