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FileSystemWacher is locking some files

I am using this code to monitor creation of files in certain folder:
_watcher = new RecoveringFileSystemWatcher(SourceFolder, "*.xml");
_watcher.Created += (_, e) =>
{
ProcessFile(e.Name);
};
RecoveringFileSystemWatcher is a fileSystemWatcher wrapper. It's constructor is:
public RecoveringFileSystemWatcher (string path, string filter)
{
_containedFSW = new FileSystemWatcher(path, filter);
}
The process works as expected but for some files, randomly, an exception is thrown telling that the file is used by another process.
This is the method that is launched upon file creation:
var nfo = new FileInfo(filePath);
if (nfo.Exists)
{
var archivoXml = nfo.Name;
string archivo = String.Empty;
try
{
string content = Task.Run(async () => await GetFileContent(filePath)).Result;
if (String.IsNullOrEmpty(content))
return false;
XmlDocument xml = new XmlDocument();
xml.LoadXml(content);
//The rest of the method
}
}
the method GetFileContent is this:
private async Task<string> GetFileContent(string filePath)
{
string content = String.Empty;
try
{
Console.Write("ONE - "); InfoLog.Save($"ONE {filePath}");
using (StreamReader sr = new StreamReader(filePath))
{
Console.Write("TWO - "); InfoLog.Save($"TWO {filePath}");
content = await sr.ReadToEndAsync().ConfigureAwait(false);
Console.Write($"THREE {(sr.BaseStream == null ? "Closed" : "Opened")} - "); InfoLog.Save($"THREE {(sr.BaseStream == null ? "Closed" : "Opened")} {filePath}");
sr.Close();
Console.WriteLine($"FOUR {(sr.BaseStream == null ? "Closed" : "Opened")}"); InfoLog.Save($"FOUR {(sr.BaseStream == null ? "Closed" : "Opened")} {filePath}");
}
}
catch (Exception ex)
{
InfoLog.Save($"XML file could be read -> {filePath}. See error log.");
ErrorLog.Save(ex);
}
return content;
}
Look at the log information I am writing to debug the process.
I got one case with a file called 1112186.xml.... this is recorded in the log:
18/12/2018 19:12:10 ONE D:\GestorDocumental\Origen\1112186.xml
18/12/2018 19:12:10 XML file could not be read -> D:\GestorDocumental\Origen\1112186.xml. See error log.
As you see, the exception is thrown at the "using" instruction.
If I see the full log, I can see that file, 1112186.xml, is never used before, so the only chance is that FSW keeps the file opened. I don't know why, but it seems this is happening.
It is clear also that this process is locking the file, because when I exit the console application and then run again, the file can be processed.
Any help about this, please?
thanks
Jaime

I usually use this method to check if file is locked. I got it from one of the link in stackoverflow.
public static bool IsFileClosed(string filepath)
{
bool fileClosed = false;
int retries = 20;
const int delay = 400; // set a delay period = retries*delay milliseconds
if (!File.Exists(filepath))
return false;
do
{
try
{
// Attempts to open then close the file in RW mode, denying other users to place any locks.
FileStream fs = File.Open(filepath, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
fs.Close();
fileClosed = true; // success
}
catch (IOException) { }
retries--;
if (!fileClosed)
Thread.Sleep(delay);
}
while (!fileClosed && retries > 0);
return fileClosed;
}
This is a new class called FileTimerWatcher (it will have logger injected):
public FileTimerWatcher(ILogger logger) : base(logger)
{
if (timer == null)
{
// Create a timer with a 1.5 second interval.
// monitor the files after 1.5 seconds.
timer = new Timer(delay);
// Hook up the event handler for the Elapsed event.
timer.Elapsed += new ElapsedEventHandler(ProcessFolder);
timer.AutoReset = true;
timer.Enabled = true;
}
}
private void ProcessFolder(object sender, ElapsedEventArgs e)
{
var LastChecked = DateTime.Now;
string[] files = System.IO.Directory.GetFiles(SourceDirectory, somefilter, System.IO.SearchOption.TopDirectoryOnly);
foreach (string file in files)
{
ProcessFile(file); // process file here
}
}

C# print file, wait for close file - program hang up

I wrote program that listens on a directory (GUI - WPF). When the new file show up in this directory is sent to the printer. The problem occurs when I try to save a large file to this directory. I have to wait until the file is closed, and then send it to the printer. I have a function that checks if the file is open. But when I use it in the whole GUI hangs. How do I use this function asynchronously?
protected void newfile(object fscreated, FileSystemEventArgs Eventocc)
{
try
{
string CreatedFileName = Eventocc.Name;
FileInfo createdFile = new FileInfo(CreatedFileName);
string extension = createdFile.Extension;
string eventoccured = Eventocc.ChangeType.ToString();
fsLastRaised = DateTime.Now;
this.Dispatcher.Invoke((Action)(() =>
{
String file = "";
file = watchingFolder + "\\" + CreatedFileName;
//printing
this.Dispatcher.Invoke((Action)(() =>
{
FileInfo info = new FileInfo(file);
while (!IsFileReady(info)) { }
var t = new Thread(() => printFile(file, extension)); //send to printer
t.Start();
}));
}));
}
}
catch (Exception ex)
{
System.Windows.Forms.MessageBox.Show("Error");
}
}
IsFileReady function:
public static bool IsFileReady(FileInfo file)
{
FileStream stream = null;
try
{
stream = file.Open(FileMode.Open, FileAccess.Read, FileShare.None);
}
catch (IOException)
{
//the file is unavailable because it is:
//still being written to
//or being processed by another thread
//or does not exist (has already been processed)
return true;
}
finally
{
if (stream != null)
stream.Close();
}
//file is not locked
return false;
}
And printfile
public void printFile(string filepath, string ext)
{
ProcessStartInfo info = new ProcessStartInfo();
info.Verb = "print";
info.FileName = filepath;
info.CreateNoWindow = true;
info.WindowStyle = ProcessWindowStyle.Hidden;
Process p = new Process();
p.StartInfo = info;
p.Start();
p.WaitForInputIdle();
System.Threading.Thread.Sleep(3000);
if (false == p.CloseMainWindow())
p.Kill();
}
}
How can I correct this code to work with large files without hangs up?
EDIT:
For check new file I use FileSystemWatcher
private void start(object sender, RoutedEventArgs e)
{
if (watchingFolder == null)
{
}
else
{
fs = new FileSystemWatcher(watchingFolder, "*.*");
fs.EnableRaisingEvents = true;
fs.IncludeSubdirectories = true;
fs.Created += new FileSystemEventHandler(newfile);
btnSatrt.IsEnabled = false;
btnStop.IsEnabled = true;
}
}

You're executing while (!IsFileReady(info)) { } through Dispatcher.Invoke, that executes the code on the UI thread so it will block for sure the app.
You aren't interacting at all with the UI, so the correct approach is to execute it asynchronously, via Tasks and awaits or with a background thread via the ThreadPool and not using at all Dispatcher.Invoke.

Try to execute all code in the newfile event handler on a background thread by starting a new task:
protected async void newfile(object fscreated, FileSystemEventArgs Eventocc)
{
try
{
await Task.Run(() =>
{
string CreatedFileName = Eventocc.Name;
FileInfo createdFile = new FileInfo(CreatedFileName);
string extension = createdFile.Extension;
string eventoccured = Eventocc.ChangeType.ToString();
fsLastRaised = DateTime.Now;
string file = watchingFolder + "\\" + CreatedFileName;
FileInfo info = new FileInfo(file);
while (!IsFileReady(info)) { }
printFile(file, extension);
});
}
catch (Exception ex)
{
System.Windows.Forms.MessageBox.Show("Error");
}
}

Use a BackgroundWorker instead of Dispatcher.Invoke.

Winforms background worker gets stuck

I am trying to build a simple code that joins csv files into one distinct file, but my background worker seems to have a mind of its own and my code gets stuck every time.
Here is my code for joining the file using the background worker:
private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
try
{
if (string.IsNullOrEmpty(saveFilePath))
{
this.Invoke(new MethodInvoker(delegate
{
btnBrowseSave.PerformClick();
}));
}
if (!string.IsNullOrEmpty(saveFilePath))
{
if (dragEventArgs != null)
files = (string[])dragEventArgs.Data.GetData(DataFormats.FileDrop);
int filesCount = 0, rowsCount = 0;
foreach (string file in files)
{
filesCount++;
int fileTotalLines = File.ReadAllLines(file).Length;
this.Invoke(new MethodInvoker(delegate
{
lblFileName.Text = "Loading file: " + file.Substring(file.LastIndexOf("\\") + 1);
lblTotalFiles.Text = "File " + filesCount + " of " + files.Length;
}));
using (StreamReader reader = new StreamReader(file))
{
using (StreamWriter writer = new StreamWriter(saveFilePath))
{
while (!reader.EndOfStream)
{
try
{
while (stopPosition > rowsCount)
{
reader.ReadLine();
rowsCount++;
}
string email = reader.ReadLine().Trim();
if (!string.IsNullOrEmpty(email) && !dicEmails.ContainsKey(email))
{
dicEmails.Add(email, null);
writer.WriteLine(email);
}
rowsCount++;
stopPosition++;
backgroundWorker.ReportProgress((rowsCount * 100 / fileTotalLines), (int)ProgressType.Row);
if (backgroundWorker.CancellationPending)
return;
}
catch (Exception ex)
{
hadReadErrors = true;
}
}
}
}
backgroundWorker.ReportProgress(0, (int)ProgressType.Row);
backgroundWorker.ReportProgress((filesCount * 100 / files.Length), (int)ProgressType.File);
}
}
}
catch (Exception ex)
{
hadReadErrors = true;
MessageBox.Show(ex.Message);
}
finally
{
backgroundWorker.Dispose();
}
}
private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
try
{
switch ((int)e.UserState)
{
case (int)ProgressType.Row:
lblFileProgress.Text = e.ProgressPercentage + "%";
fileProgressBar.Value = e.ProgressPercentage;
break;
case (int)ProgressType.File:
lblTotalProgress.Text = e.ProgressPercentage + "%";
totalProgressBar.Value = e.ProgressPercentage;
break;
}
}
catch (Exception ex) { }
}
When I run in debug mode and go with the debugger I don't see any problems, but when I let the code run it self it gets stuck and crashes.
Can someone PLEASE help me and tell me what am I missing out here ?
Here is the exception:
Managed Debugging Assistant 'ContextSwitchDeadlock' has detected a problem in
'C:\Users\Develop\Desktop\ExcelBuilder\ExcelBuilder\bin\Debug\ExcelBuilder.vshost.exe'.
Additional information: The CLR has been unable to transition from COM context 0x90fb78
to COM context 0x90fc30 for 60 seconds. The thread that owns the destination
context/apartment is most likely either doing a non pumping wait or processing a very
long running operation without pumping Windows messages. This situation generally has
a negative performance impact and may even lead to the application becoming non
responsive or memory usage accumulating continually over time. To avoid this problem,
all single threaded apartment (STA) threads should use pumping wait primitives
(such as CoWaitForMultipleHandles) and routinely pump messages during long running operations.

I did a small example of your program, trying to guess what it must do (https://github.com/anderson-rancan/stackoverflow_28798348, drag and drop 4 files to the groupbox, lorem?.csv), and there is a few things that you should consider:
never try/catch a unknown exception, every exception or something you cannot deal with (https://msdn.microsoft.com/en-us/library/ms182137.aspx)
when using a BackgroundWorker on a form, use the "sender" for references to it, it's a thread safe object to your method (https://msdn.microsoft.com/en-us/library/cc221403(v=vs.95).aspx)
maybe you are updating too fast your form, change your Invoke method to BeingInvoke, and do the update async (https://msdn.microsoft.com/en-us/library/0b1bf3y3(v=vs.110).aspx)
So, just fixing that was possible to run it, like this:
private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker bckw = (BackgroundWorker)sender; // Recommended way, thread safe
try
{
if (string.IsNullOrEmpty(saveFilePath))
{
this.Invoke(new MethodInvoker(delegate
{
btnBrowseSave.PerformClick();
}));
}
if (!string.IsNullOrEmpty(saveFilePath))
{
if (dragEventArgs != null)
files = (string[])dragEventArgs.Data.GetData(DataFormats.FileDrop);
int filesCount = 0, rowsCount = 0;
foreach (string file in files)
{
filesCount++;
double fileTotalLines = File.ReadAllLines(file).Length;
this.BeginInvoke(new MethodInvoker(delegate
{
lblFileName.Text = "Loading file: " + file.Substring(file.LastIndexOf("\\") + 1);
lblTotalFiles.Text = "File " + filesCount + " of " + files.Length;
})); // Invoke async, way too fast this...
using (StreamReader reader = new StreamReader(file))
{
using (StreamWriter writer = new StreamWriter(saveFilePath))
{
while (!reader.EndOfStream)
{
try
{
while (stopPosition > rowsCount)
{
reader.ReadLine();
rowsCount++;
} // why are you using that? it won't get TRUE
string email = reader.ReadLine().Trim();
if (!string.IsNullOrEmpty(email) && !dicEmails.ContainsKey(email))
{
dicEmails.Add(email, null);
writer.WriteLine(email);
}
rowsCount++;
stopPosition++;
bckw.ReportProgress((int)Math.Round(rowsCount * 100 / fileTotalLines, 0), (int)ProgressType.Row);
if (bckw.CancellationPending)
return;
}
catch (Exception ex)
{
hadReadErrors = true;
throw; // Throw it again, or you won't know the Exception
}
}
}
}
bckw.ReportProgress(0, (int)ProgressType.Row);
bckw.ReportProgress((filesCount * 100 / files.Length), (int)ProgressType.File);
}
}
}
catch (Exception ex)
{
hadReadErrors = true;
MessageBox.Show(ex.Message);
}
finally
{
bckw.Dispose();
}
}
private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
//try
//{
switch ((int)e.UserState)
{
case (int)ProgressType.Row:
lblFileProgress.Text = e.ProgressPercentage + "%";
if (e.ProgressPercentage <= fileProgressBar.Maximum)
fileProgressBar.Value = e.ProgressPercentage;
break;
case (int)ProgressType.File:
lblTotalProgress.Text = e.ProgressPercentage + "%";
totalProgressBar.Value = e.ProgressPercentage;
break;
}
//}
//catch (Exception ex) { } // Don't catch everything
}
Finally, may I suggest another approach?
You're reading the file two times: one to get the number of lines, and another to read each line. Try to do this just once, you'll get a better result.

C# Progressbar & Textbox Not Updating

I've seen some great answers here and was wondering if someone could help me out.
Here's my code:
namespace expandGUIWPF
{
public static string getSHA256b64(string filepath)
{
byte[] bytes = SHA256.Create().ComputeHash(File.ReadAllBytes(filepath));
return Convert.ToBase64String(bytes);
}
private void btnRun_Click(object sender, RoutedEventArgs e)
{
{
string folder = txtFolder.Text;
string filelist = folder + "\\FileList.txt";
string[] test = Directory.GetFiles(folder, "*", System.IO.SearchOption.AllDirectories);
File.WriteAllLines(filelist, test);
int length = File.ReadLines(filelist).Count();
pBar1.Minimum = 1;
pBar1.Maximum = length;
File.WriteAllLines(filelist, test);
using (StreamReader sr = new StreamReader(filelist))
{
string line;
while ((line = sr.ReadLine()) != null)
{
string oldfile = line;
string newfile = oldfile + ".expanded";
string oldhash = "";
string newhash = "";
try
{
ProcessStartInfo startInfo = new ProcessStartInfo(#"C:\test\test.exe", oldfile + " " + newfile);
startInfo.WindowStyle = ProcessWindowStyle.Hidden;
Process.Start(startInfo);
Thread.Sleep(1000);
if (File.Exists(oldfile))
{
oldhash = getSHA256b64(oldfile);
}
if (File.Exists(newfile))
{
newhash = getSHA256b64(newfile);
File.Delete(oldfile);
File.Move(newfile, oldfile);
}
pBar1.Value = pBar1.Value + 1;
txtLog.AppendText(oldfile + "\r\n Old: " + oldhash + "\r\n New: " + newhash + "\r\n");
if (!(oldhash == newhash))
{
txtLog.AppendText("Successfully expanded file \r\n");
}
else
{
txtLog.AppendText("Unable to expand file \r\n");
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
}
}
}
}
The problem is that my progressbar isn't updating. I know a little C# but I'm a beginner to WPF and can't get my head around setting up a background worker to update my UI. Would someone be able to give me a few pointers please? Currently the app works fine, but the progressbar jumps to 100% finished and all of the text suddenly appears.
Thanks in advance!
Tom

First you'll want your background worker to handle the processes in its DoWork event. Within that event you can call the ProgressChanged event to update the progress bar. Below is an example:
private void btnRun_Click(object sender, RoutedEventArgs e)
{
if(workerThread.IsBusy == false) // Make sure someone doesn't click run multiple times by mistake
{
pBar1.Value = 0;
workerThread.RunWorkerAsync();
}
}
private void workerThread_DoWork(object sender, DoWorkEventArgs e)
{
// Definitions and so forth
pBar1.Minimum = 0;
pBar1.Maximum = length;
int status = 0;
using (StreamReader sr = new StreamReader(filelist))
{
string line;
while ((line = sr.ReadLine()) != null)
{
// Try/Catch work here
status++;
workerThread.ReportProgress(status);
}
}
private void workerThread_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
pBar1.Value = e.ProgressPercentage;
}

Just understand that the thread that's running the Form is the same one that will be used to update the form's controls. So if you have 'stuff' to do - like encrypting / decrypting lines from a file - you need to perform those items on another thread with a callback, otherwise the form display wont update until it's done with your stuff to do. You can raise events from inside a worker thread -- and catch them using an event handler on the main (form) thread to update the progress bar.

It seems that your UI thread is being blocked, in windows forms programming you have one message pump and while you main thread (UI) is doing something else it has to wait before it can process messages. You can fix this problem by setting up a background worker to send updates
For more information on UI thread and the message pump see this
http://www.codeproject.com/Articles/10311/What-s-up-with-BeginInvoke
For infomation on the backgroundworker thread see this
http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx
Small Example code
// This event handler is where the time-consuming work is done.
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int i = 1; i <= 10; i++)
{
if (worker.CancellationPending == true)
{
e.Cancel = true;
break;
}
else
{
// Perform a time consuming operation and report progress.
System.Threading.Thread.Sleep(500);
worker.ReportProgress(i * 10);
}
}
}

Update ui thread

I have a ListBox which I put some files, if the file is not AVI I automatically converts it but I want when the files converting message will write on a label that the files are now converted to another format, i know i need use Dispatcher in order to update the UI thread but i use now Winform instead of WPF, and i need help with this.
BTW i cannot use Task because i am using .Net 3.5
private void btnAdd_Click(object sender, EventArgs e)
{
System.IO.Stream myStream;
OpenFileDialog thisDialog = new OpenFileDialog();
thisDialog.InitialDirectory = "c:\\";
thisDialog.Filter = "All files (*.*)|*.*";
thisDialog.FilterIndex = 1;
thisDialog.RestoreDirectory = false;
thisDialog.Multiselect = true; // Allow the user to select multiple files
thisDialog.Title = "Please Select Source File";
thisDialog.FileName = lastPath;
List<string> list = new List<string>();
if (thisDialog.ShowDialog() == DialogResult.OK)
{
foreach (String file in thisDialog.FileNames)
{
try
{
if ((myStream = thisDialog.OpenFile()) != null)
{
using (myStream)
{
listBoxFiles.Items.Add(file);
lastPath = file;
}
}
}
catch (Exception ex)
{
MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message);
}
}
for (int i = 0; i < listBoxFiles.Items.Count; i++)
{
string path = (string)listBoxFiles.Items[i];
FileInfo fileInfo = new FileInfo(path);
if (fileInfo.Extension != ".AVI")
{
listToRemove.Add(path);
}
}
(new System.Threading.Thread(sendFilesToConvertToPcap)).Start();
foreach (string file in listToRemove) //remove all non .AVI files from listbox
{
listBoxFiles.Items.Remove(file);
}
}
}
this function need to change the Label:
public void sendFilesToConvertToPcap()
{
if (listToRemove.Count == 0) // nothing to do
{
return;
}
lblStatus2.Content = "Convert file to .AVI...";
foreach (String file in listToRemove)
{
FileInfo fileInfo = new FileInfo(file);
myClass = new (class who convert the files)(fileInfo);
String newFileName = myClass.mNewFileName;
listBoxFiles.Items.Add(myClass._newFileName);
}
lblStatus2.Content = "Finished...";
}

From your question, it seems that you'd like to convert several files. You may want to consider using the BackgroundWorker class and overwrite the DoWork and ProgressChanged events as described in this article. You can update the label and other controls in the ProgressChanged event.

public void sendFilesToConvertToPcap()
{
.....
....
this.Invoke((MethodInvoker)delegate {
lblStatus2.Text = "Convert file to .AVI..."; });
....
}

This is a very common requirement for long-running processes. If you don't explicitly call methods on a separate thread, they will automatically run on the main (see: UI) thread and cause your UI to hand (as I suspect you already know).
http://www.dotnetperls.com/backgroundworker
Here is an old, but excellent link with an example on how to use the background worker to handle the threadpool for you.
This way, you can just create a worker to manage running your conversion process on a separate thread, and I believe there is even an example for creating a process bar.