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01.30.2006 at 10:41AM PST, ID: 21715816
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The process cannot access the file because it is being used by another process...
Zone: .NET
Tags: access, file, cannot, used, another
Hi experts! I'm having a problem using a WebClient. It seems that I keep getting the old "process cannot access the file because it is being used by another process" excpetion. Somehow, my own code must be causing this problem, because even after a total reboot it has the same prob (ie no other executable is tying up the file that is needed).

Here is my code. I'm lazy - i put down debug points in the catch() blocks. I don't output anything to the screen. But you can see where it always "catches" by my comment.


try
                              {
                                    WebClient client = new WebClient();
                                    FileStream fileStream = new FileStream(tempFile,
                                          FileMode.Open,
                                          FileAccess.Read,
                                          FileShare.None);

                                    client.DownloadFile(ConnectString, tempFile);

                                    if (!fileStream.CanRead)
                                    {
                                          string fileName = fileStream.Name;
                                          fileStream.Close();
                                          fileStream = new FileStream(tempFile, FileMode.Open, FileAccess.Read);
                                    }

                                    StreamReader streamReader = new StreamReader(fileStream);

                                    fileStream.Close();
                                    fileStream = new FileStream(tempFile, FileMode.Open, FileAccess.Read);
                                    streamReader = new StreamReader(fileStream);

                                    string[] discreteInfo = null;

                                    while (streamReader.Peek() != -1)
                                    {
                                          string Info = streamReader.ReadLine();
                                          discreteInfo = delimitedInfo.Split(new char[1] {','});
                                    }

                                    hashTable.Add(symbol, discreteInfo);
                              }
                              catch(System.IO.IOException)
                              {
                                    ;
                              }
                              catch(System.Net.WebException)
                              {
                                    ; // debug point always stops here...
                              }
                              finally
                              {
                                    
                              }


Here is the error message output:

See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.Net.WebException: An exception occurred during a WebClient request. ---> System.IO.IOException: The process cannot access the file "C:\DOCUME~1\Owner\LOCALS~1\Temp\tmp4E.tmp" because it is being used by another process.
   at System.IO.__Error.WinIOError(Int32 errorCode, String str)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean useAsync, String msgPath, Boolean bFromProxy)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access)
   at System.Net.WebClient.DownloadFile(String address, String fileName)
   --- End of inner exception stack trace ---
 


Could this be solved with .dispose() or using()? I havent ever used those before.

Anyway, I'm stuck on this problem and could use some expert advice. Many thanks for your suggestions!

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Question Stats
Zone: Programming
Question Asked By: sapbucket
Solution Provided By: TitoPeru
Participating Experts: 3
Solution Grade: A
Views: 909
Translate:
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01.30.2006 at 11:19AM PST, ID: 15826549

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01.30.2006 at 11:27AM PST, ID: 15826638

Rank: Genius

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01.30.2006 at 11:27AM PST, ID: 15826653

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01.30.2006 at 11:32AM PST, ID: 15826700

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01.30.2006 at 11:38AM PST, ID: 15826761

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01.30.2006 at 12:13PM PST, ID: 15827155

Rank: Master

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01.30.2006 at 04:15PM PST, ID: 15829556

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01.30.2006 at 05:10PM PST, ID: 15829813

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01.30.2006 at 11:19AM PST, ID: 15826549
my code snippet above is terrible. I re-wrote it:

                              string tempFile = Path.GetTempFileName();

                              WebClient client = new WebClient();

                              FileStream fileStream = new FileStream(tempFile,
                                                                     FileMode.Open,
                                                                     FileAccess.Read,
                                                                     FileShare.None);

                              StreamReader streamReader = new StreamReader(fileStream);

                              int numQoutes = 0;

                              try
                              {
                                    if (!fileStream.CanRead)
                                    {
                                          fileStream.Close();
                                          fileStream = new FileStream(tempFile, FileMode.Open, FileAccess.Read);
                                    }

                                    client.DownloadFile(ConnectString, tempFile);

                                    while (streamReader.Peek() != -1)
                                    {
                                          streamReader.ReadLine();
                                          numQoutes++;
                                    }
                              }
                              catch (IOException)
                              {
                                    ;
                              }
                              catch (WebException)
                              {
                                    ;
                              }
                              finally
                              {
                                    client.Dispose();
                                    fileStream.Close();
                                    streamReader.Close();
                              }



 
01.30.2006 at 11:27AM PST, ID: 15826638

Rank: Genius

What are the steps through this code?

                              if (!fileStream.CanRead)
                              {
                                   fileStream.Close();
                                   fileStream = new FileStream(tempFile, FileMode.Open, FileAccess.Read);
                              }

                              client.DownloadFile(ConnectString, tempFile);

You are not closing the file stream in the if block.

Bob
 
01.30.2006 at 11:27AM PST, ID: 15826653
hmm i noticed that the tempFile returned by

string tempFile = Path.GetTempFileName();

is the same file that the expection pukes on.

I tried replacing

string tempFile = Path.GetTempFileName();

with

string tempFile = "c:\\tempFile.txt";

And i get the same expection!

System.Net.WebException: An exception occurred during a WebClient request. ---> System.IO.IOException: The process cannot access the file "c:\tempFile.txt" because it is being used by another process.

So, some process of mine is not releasing the file so that I can access it.
 
01.30.2006 at 11:32AM PST, ID: 15826700
TheLearnedOne, I pulled that bit of code out of the C# Cookbook. I commented it out, and still get the same problem.

                              //if (!fileStream.CanRead)
                              //{
                              //     fileStream.Close();
                              //     fileStream = new FileStream(tempFile, FileMode.Open, FileAccess.Read);
                              //}

                              client.DownloadFile(ConnectString, tempFile);
 
01.30.2006 at 11:38AM PST, ID: 15826761
If you would like to try this for yourself (with this connect string it should return a count of 3066):

            public int CountNumberOfQoutes()
            {
                  string connectString = "http://ichart.yahoo.com/table.csv?s=pgic&a=00&b=2&c=1900&d=01&e=01&f=2006&g=d&ignore=.csv";
                  string tempFile = Path.GetTempFileName();
                  //string tempFile = "c:\\DemoSymboleOutput.txt";

                  WebClient client = new WebClient();

                  FileStream fileStream = new FileStream(tempFile,
                                                         FileMode.Open,
                                                         FileAccess.Read,
                                                         FileShare.None);

                  StreamReader streamReader = new StreamReader(fileStream);

                  int numQoutes = 0;

                  try
                  {
                        //                                    if (!fileStream.CanRead)
                        //                                    {
                        //                                          fileStream.Close();
                        //                                          fileStream = new FileStream(tempFile, FileMode.Open, FileAccess.Read);
                        //                                    }

                        client.DownloadFile(connectString, tempFile);

                        client.Dispose();

                        while (streamReader.Peek() != -1)
                        {
                              streamReader.ReadLine();
                              numQoutes++;
                        }
                  }
                  catch (IOException)
                  {
                        ;
                  }
                  catch (WebException)
                  {
                        ;
                  }
                  finally
                  {
                        client.Dispose();
                        fileStream.Close();
                        streamReader.Close();
                  }

                  return numQoutes;
            }
 
01.30.2006 at 12:13PM PST, ID: 15827155

Rank: Master

Little off the topic as the lock is probably caused by your application so you already know what is locking you file. This freeware shell extension let you see what process is locking your file (such as spyware) form windows explorer.

http://www.dr-hoiby.com/WhoLockMe/index.php


AT
 
01.30.2006 at 04:15PM PST, ID: 15829556
You self are locking the file, try FileShare.Read instead FileShare.None in the first instance of fileStream

Tito
Accepted Solution
 
01.30.2006 at 05:10PM PST, ID: 15829813
doh!

thats why a fresh set of eyes helps   :)


Many Thanks
 
 
20080236-EE-VQP-29