IOException: The Process can not access the file filename

Question

4.00/5 (3 votes)

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I am using the following code to save the data in the text file

C#

public void Logtext(string txt, string fn)
{
    try
    {
      StreamWriter sw = File.AppendText(fn);
      sw.WriteLine(txt);
    }
    catch {...}
    finally
    {
      sw.Flush();
      sw.Close();
      sw.Dispose();
    }
}

Sometimes File.AppendText(fn) statement throws an exception as:
The file can not access the file, it is used by another process.

This the only function from where the file is handled and only single instance of this application is running. I also checked the call stack for same function call. How can I handle this problem?

Posted 18-Apr-11 0:53am

Naina Dhande

Updated 18-Apr-11 1:02am

Ankur^\m/

v2

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Xgener · Answer 1 · 2011-04-19T02:02:00

Solution 5

It would be better.

public class WriteIntoFile {
     private static object m_LogSync  = new object();

     public static void Logtext(string txt, string fn){
         lock(m_LogSync){
               using(StreamWriter sw = File.AppendText(fn)){
                     sw.WriteLine(txt);
               }
         }
    }
}

call like this WriteIntoFile.Logtext("abc", "C:\\temp");
I think it would work

Posted 19-Apr-11 2:02am

Xgener

Comments

BobJanova 19-Apr-11 10:11am

As long as it is only a single process which is using this file (see Nishant's answer about Mutexes – or Mutices? heh – for what to do in the case where it is not), this should work.

Remember that if you are writing a LOT of log information, this approach forces them all to pipeline and blocks other processing on the file I/O, so it may not be appropriate. But unless the log volume is huge that will not be a problem.

Nish Nishant · Answer 2 · 2011-04-18T01:27:00

Solution 2

If it's an inter-process issue, using lock won't help much since lock is not OS-wide. For inter-process synchronization, you will need to use a Mutex.

Posted 18-Apr-11 1:27am

Nish Nishant

Comments

Naina Dhande 18-Apr-11 7:43am

How can I implement it!

Naina Dhande 18-Apr-11 7:49am

Will follwing help?
mtx.WaitOne
followed by code
mtx.RelaeseMutex

Tarun.K.S 18-Apr-11 8:07am

Just checked in a book. Yes that's right.
if(mutex.WaitOne())
{
try
{
//Work to be done
}
finally
{
mutex.ReleaseMutex();
}
}
else
{
//Some error occured
}

Naina Dhande 19-Apr-11 3:26am

Use of Mutex is not helping.

Nish Nishant 19-Apr-11 8:35am

Probably because you are not using it correctly. Share some code.

BobJanova 19-Apr-11 10:09am

The question states that only one instance of the app is running at one time, so the log file shouldn't be being written from two processes at once, although this is nevertheless valuable information.

#realJSOP · Answer 3 · 2011-04-18T01:56:00

You could use a FileSystemWatcher object to watch the file to be closed, and then in that event handler, you could do whetever you need to do to the file. Google is your friend, but I wrote an article series about using the FileSystemWatcher object that might help:

FileSystemWatcher - Pure Chaos (Part 1 of 2)[^]

FileSystemWatcher - Pure Chaos (Part 2 of 2)[^]

Part 2 uses the sample app created in Part 1 to illustrate how various programs manipulate files, and how the FileSystemWatcher responds to them.

nit_singh · Answer 4 · 2011-04-18T01:14:00

Solution 1

You are getting this exception because may be some other process is still writing something to that file.

So you have to first lock the object. Try like that, it may solve your problem.

C#

lock (sw)
{
         sw.WriteLine(txt);
}

Posted 18-Apr-11 1:14am

nit_singh

Comments

Naina Dhande 18-Apr-11 7:20am

Thanks

Tarun.K.S 18-Apr-11 7:23am

Good answer! My 5. I did learn a new thing here.

Nish Nishant 18-Apr-11 7:28am

The answer is not accurate though. C#'s lock will not help with inter-process sync-ing.

Tarun.K.S 18-Apr-11 7:59am

Oh I thought it did work as Naina accepted the answer. Thanks for pointing that out.

Naina Dhande 18-Apr-11 7:44am

Hi Nitin

sorry! but lock(sw) did not worked

#realJSOP 18-Apr-11 7:53am

Right, and everyone else that's looked at this question knew it wouldn't.

BobJanova 19-Apr-11 10:09am

sw is a local object created as a result of the failing call, of course this will not work!

IOException: The Process can not access the file filename

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