I have Following Code in a Page_Load called function. When the Page is loaded the first time after starting Visual Studio, everything works out fine.
But any other opening call to the File after that returns IOException: "File is in use by another process", even when directly opening the File in VisualStudio Solution this Error is returned(of course not as Exception)
FileStream mailinglist_FileStream = new FileStream(#"\foobarFile.txt", FileMode.Open);
PeekingStreamReader mailinglist_Reader = new PeekingStreamReader(mailinglist_FileStream);
//Do some stuff with the file
mailinglist_FileStream.Close();
mailinglist_Reader.Close();
mailinglist_Reader.Dispose();
mailinglist_FileStream.Dispose();
Why is the file still locked? and why does fully restarting Visual Studio reset the File?
when checking file-Properties it says:
Build Action: Content
Copy to output directory: do not Copy
I am only reading this File. can i do something similiar to adLockOptimistic, so that multiple processes can access the File?
Why is the file still locked? and why does fully restarting Visual
Studio reset the File? when checking file-Properties it says [...]
I don't know why the file is still locked: probably because your code fails before the stream is closed/disposed.
About "why fully restarting Visual Studio [...]": because you may be using IIS Express or ASP.NET Dev Server whose are closed when you close the IDE, so locks on files are released since the process holding the locks is no longer running.
And about "why is the file still locked?[...]" it could be because the file stream isn't closed because sometimes the thread may not end successfully and the locks aren't released.
As other answer said, check how using block may avoid that IDisposable objects wouldn't be disposed:
// FileShare.ReadWrite will allow other processes
// to read and write the target file even if other processes
// are working with the same file
using var mailinglist_FileStream = new FileStream(#"\foobarFile.txt", FileMode.Open, FileShare.ReadWrite);
using var mailinglist_Reader = new PeekingStreamReader(mailinglist_FileStream);
// Do your stuff. Using blocks will call Dispose() for
// you even if something goes wrong, as it's equal to a try/finally!
I am only reading this File. can i do something similiar to
adLockOptimistic, so that multiple processes can access the File?
Yes, take a look at File.Open method and FileShare enumeration:
File.Open: http://msdn.microsoft.com/en-us/library/y973b725.aspx
FileShare enum: http://msdn.microsoft.com/en-us/library/system.io.fileshare.aspx
Learn to use using:
using (FileStream fileStream = File.Open(#"C:\somefile", FileMode.Open, FileAccess.Read))
{
...
}
The using construct ensures that the file will be closed when you leave the block even if an exception is thrown.
Your problem might not be here, but somewhere else in your code. You'll have to go through all your code and look for places where you have opened files but not put it inside a using statement.
An old question but unfortunately the given answers can be not applicable to the question.
The problem specifically in Windows lies in two aspects of Windows behavior:
a) when the handle to the file, opened for writing, is closed, the Microsoft Antimalware Service opens the file to check the newly written data for malware;
b) the OS itself keeps the file opened for some time after all handles to it are closed. This time can be from seconds to many minutes depending on the nature of the file and other factors.
We saw this problem many times in our products and had to provide special support for this case - our kernel-mode attempts to close the file as soon as the last handle to it is closed.
Try using using blocks, it may not fix your lock problem, but it is better form for disposable objects.
using (FileStream mailinglist_FileStream = new FileStream(#"\foobarFile.txt", FileMode.Open))
{
using (PeekingStreamReader mailinglist_Reader = new PeekingStreamReader(mailinglist_FileStream))
{
...
}
}
Also, try closing mailinglist_Reader before mailinglist_FileStream.
Related
In my application, one user at a time is supposed to work with an Access DB file for the entire "session" (time span he has the application open). The file shall be locked while one user is working with it.
I do so by using lock according to:
How to lock a file with C#?
FileStream s2 = new FileStream(name, FileMode.Open, FileAccess.Read, FileShare.None);
However when accessing the file via code, an exception is thrown, e.g.:
// Connection points to file locked before
using (OleDbConnection connection = new OleDbConnection(Connection)) {
connection.Open();
//...
System.Data.OleDb.OleDbException File is already being used
How to access previously locked file? Do I always have to remove the lock before accessing it? If so, how to ensure the file is not being accessed inbetween unlocking, accessing and relocking?
I think your connection must be Exclusive: http://www.connectionstrings.com/access/
The solution is indeed to create a separate lock file and lock this using a file stream.
(The answer is actually given by Sinatr, just for the sake of completeness I want to share it. Yet to find out is what MS Office does to its office files, as that is the exact behavior I'd like to have - but that is a different question.)
I have the following code:
using (MemoryStream str = new MemoryStream())
{
Program.api.GetDocument(result, str);
using (FileStream fileStream = File.Create(filePath))
{
str.WriteTo(fileStream);
}
}
Whenever a file is written, it is always locked afterwards - attempting to delete it or modify it causes Windows to tell me the file is in use, even after closing my application. Am I missing something?
Your problem is most likely caused by Windows Search Indexing which is a part of Windows Search. If you attempt to access the file immediately (or very shortly) after modifying it, you may run into the sort of issues you are seeing. The best way around this is to add retry logic to the file operation you are performing, which waits some small period of times and re-attempts the file op.
If you would like to confirm that the problem is cause by Windows File Search Indexing, you can disable it for the file type and/or location where you are writing your file to see if that makes the problem go away.
Ok guys, this one is a tough one.
The scenario:
I have multiple services running on multiple machines
Each service has multiple threads, and each thread writes a file on a FILER - the shared storage used by my machines (using a share such as \\filername\foo\bar)
The FILER machine is a NetApp machine
Both the FILER and the machines running the services are using SMB2 (http://en.wikipedia.org/wiki/Server_Message_Block)
The instruction used to write the file is as simple as the one listed below in [THE CODE]
[THE CODE]
using (StreamWriter outfile = new StreamWriter(pathToTheFile, false))
{
outfile.Write(stringToWriteInTheFile);
}
[/THE CODE]
The problem:
Sometimes the service remains "stuck" on this instruction. The error given is:
The process cannot access the file '\\filername\foo\bar\myfile.txt' because it is being used by another process.
After some of these errors, the service refuses to release the lock on the file. What happens then?
You can delete the file, but the file is IMMEDIATELY recreated. Like if a sort-of permanent Stream is alive and keeps writing the file indefinitely.
You can stop the service: it's stuck, and won't be stopped, so I forced a Thread.Abort (yeah, I know but practice, but what else?) after 2 minutes.
So, the service is now stopped, but the machine retains an handle to the file and you CANNOT kill the process keeping the handle alive except by rebooting the machine. . .
I don't know what to do right now, I think I tried everything.
Considerations:
Previously, the FILER and the machines were using SMB1, and this problem never arised. So I guess something fishy happens in the background, but I can't understand what...
I changed recently the code used to write the file, in a desperate attempt to "delegate" everything to .net. Now it's:
File.WriteAllText(pathToTheFile, stringToWriteInTheFile);
but my gut feeling is that, under the wraps, .net is doing the exact same thing - the change is quite recent though, so I can't still say if the "fix" is working or not.
EDIT (as per Vash comment): Usually the file is different, but it can happen (and it actually happens) sometimes that multiple threads are trying to write the same file, however :( - doing the File.WriteAllText shouldn't take care of concurrency issues?
Try explicitly opening a FileStream in "exclusive" mode, ie
using (var fs = new FileStream("path",
FileMode.Open, FileAccess.ReadWrite,
FileShare.None))
{
using (var sw = new StreamWriter(fs))
{
...
Of course your code will have to anticipate that the file might be locked when it goes to write it and react appropriately. That part is left as an exercise for the reader :-)
Disclaimer: I have used this in a multi-threaded environment, but I can't guarantee it will work over Samba.
I have a WPF app, which opens and edits XML files. Currently, the app can be launched multiple times, and several instances can have the same file open. I need to lock the files such that, when one is open, it won't let another instance of the app open the file. I have tried using the FileShare.None attribute when opening the file, as well as FileStream.Lock(), but for some reason, these fail to prevent a separate instance of the app from opening it.
EDIT: Relevant code
try
{
FileStream iStream = File.Open(fileName, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
iStream.Lock(0, iStream.Length);
// DO STUFF WITH FILE HERE
}
catch (System.IO.IOException ioException)
{
// Raise exception to higher level, where application will terminate.
throw (ioException);
}
You need to keep file open all the time you are "editing" it from the moment you start editing till closing (assuming you have separate processes for each instance of your app).
Your code looks like you are opening file inside on method and likely close it inside this method either by using "using" as recommended for short file operations or just letting GC to close it. As result you lock file for some time, but release it soon enough for other instances to be able to open it again.
Note that if your application implements some sort of single instance approach this locking may not be enough as all of the open operations will be executed from the same process.
I have many processes reading a file stored on a network share. Originally I was only able to have one process read the file, all the others would throw exceptions. I implemented the following code to deal with that:
using (StreamReader fileStreamReader = new StreamReader(File.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read)))
{
content = fileStreamReader.ReadToEnd();
}
This let multiple processes read the same file, however it still seems to have issues, because sometimes multiple processes still can't access the file. Yet I can go back later when the file isn't in use and open it just fine. Right now I have some retry behavior with random delays implemented that so far, seem to help. It seems a little quirky to me to do it this way, so what would be a better method?
This is the weird part, the exception I'm getting is not from file IO at all, it's from a library called CommStudio. In short, I dump the file to a string, i modify it slightly, dump it into a memory stream, and ship it off over ymodem on rs232. The exception is telling me the remote system has canceled. The device getting the data reports that there was a transmission error, which usually means that an incomplete/empty file was received.
Normally I would blame the library on this, but it works flawlessly at desk-testing and when there is only one process accessing the file. The only thing that really seems to be consistent is that it is likely to fail when multiple processes are accessing a file.
had a similar problem but not allot of time to find an ideal solution. I created a webservice and stuck the file local to the webservice app.. then created a simple one liner GET API which was called over the office intranet.. thus ensureing only the calling application edited the log file.. messy but functional.
I have had a similar problem in the past. Try changing how you access the file to something like this.
//Use FileInfo to get around OS locking of the file
FileInfo fileInfo = new FileInfo(path);
//I actually wanted unblocked read write access so change your access and share appropriately
using (FileStream fs = fileInfo.Open(FileMode.Open, FileAccess.Write, FileShare.ReadWrite))
{
//I'm using CopyTo but use whatever method matches your need
fileInfo.CopyTo(Path.Combine(destination, fileName), false);
}