The process cannot access the file because it is being used by another process. XML

Question

I am calling below method in a loop with same xmlRequestPath and xmlResponsePath files. Two loop counts it executes fine in the 3rd iteration I am getting exception "The process cannot access the file because it is being used by another process.".

    public static void UpdateBatchID(String xmlRequestPath, String xmlResponsePath)
    {
        String batchId = "";
        XDocument requestDoc = null;
        XDocument responseDoc = null;
        lock (locker)
        {
            using (var sr = new StreamReader(xmlRequestPath))
            {
                requestDoc = XDocument.Load(sr);
                var element = requestDoc.Root;
                batchId = element.Attribute("BatchID").Value;

                if (batchId.Length >= 16)
                {
                    batchId = batchId.Remove(0, 16).Insert(0, DateTime.Now.ToString("yyyyMMddHHmmssff"));
                }
                else if (batchId != "") { batchId = DateTime.Now.ToString("yyyyMMddHHmmssff"); }
                element.SetAttributeValue("BatchID", batchId);
            }

            using (var sw = new StreamWriter(xmlRequestPath))
            {
                requestDoc.Save(sw);
            }

            using (var sr = new StreamReader(xmlResponsePath))
            {
                responseDoc = XDocument.Load(sr);
                var elementResponse = responseDoc.Root;
                elementResponse.SetAttributeValue("BatchID", batchId);

            }

            using (var sw = new StreamWriter(xmlResponsePath))
            {                    
                responseDoc.Save(sw);                    
            }
        }
        Thread.Sleep(500);

        requestDoc = null;
        responseDoc = null;
    }

Exception is occurring at using (var sw = new StreamWriter(xmlResponsePath)) in above code.

Exception:

The process cannot access the file 'D:\Projects\ESELServer20130902\trunk\Testing\ESL Server Testing\ESLServerTesting\ESLServerTesting\TestData\Assign\Expected Response\Assign5kMACResponse.xml' because it is being used by another process.

Why is your responseDoc.Save(sw); creating a new instance of sw? Shouldn't it be in the same using section where you are loading it and setting the attribute? — Dijkgraaf, Nov 06 '13 at 06:24
Hi Dijkgraaf, I am creating StreamReader instance to read the XML. When I am done with setting the attribute I want to save it in same XML file. So I am creating another StreamWriter instance to save in same XML file from which I have read earlier. — Anup, Nov 06 '13 at 07:06
Is there another part of your code (after the call to the `UpdateBatchID` method) that uses the XML files? — Andrei V, Nov 06 '13 at 07:49
I think you need to close you read stream, before you can open the same file for writing. — Dijkgraaf, Nov 06 '13 at 08:02
Hi Andrei, Yes, I am loading the xml file in an object from another thread. But file access is Read. is this causing the problem. serializer = new XmlSerializer(typeof(Response)); loadStream = new FileStream(inputFileName, FileMode.Open, FileAccess.Read); Response loadedResponseObject = (Response)serializer.Deserialize(loadStream); return loadedResponseObject; — Anup, Nov 06 '13 at 08:06
@Dijkgraaf, there's no need to explicitly close the streams. The `Using` statement [does that automatically](http://stackoverflow.com/questions/4136490/do-i-need-to-explicitly-close-the-streamreader-in-c-sharp-when-using-it-to-load). — Andrei V, Nov 06 '13 at 08:19
Anup, it's a bit hard for me to see from the provided code if the file is still open. Jugging from the exception, it's probably so. As far as I see, in the other thread you don't close the `FileStream` after loading. Try adding `loadStream.Close()` before the `return`. — Andrei V, Nov 06 '13 at 08:23
Thanks Andrei, I closed the stream in another thread. That solved the problem. — Anup, Nov 06 '13 at 08:53
No problem. Glad I could help. If you're new to this, remember that all streams must be explicitly closed, unless you're opening them within the `Using` statement. — Andrei V, Nov 06 '13 at 08:56

score 0 · Answer 1 · answered Jun 24 '14 at 12:39

Maybe at the third loop the stream is still being closed, so it tells you that it is non accessible. Try waiting a bit before calling it again in the loop, for example:

while (...)
{
    UpdateBatchID(xmlRequestPath, xmlResponsePath);
    System.Threading.Thread.Sleep(500);
}

Or, close explicitly the stream instead of leaving the work to the garbage collector:

var sr = new StreamReader(xmlResponsePath);
responseDoc = XDocument.Load(sr);
     ....
sr.Close();

score 0 · Answer 2 · answered Jun 24 '14 at 12:49

Instead of using two streams, a Write and a Read stream, try using only a FileStream, since the problem might be that after loading the file the stream remains opened until the garbadge collector actives.

using (FileSteam f = new FileStream(xmlResponsePath))
{
     responseDoc = XDocument.Load(sr);

     var elementResponse = responseDoc.Root;
     elementResponse.SetAttributeValue("BatchID", batchId);

     responseDoc.Save(sw);                    
}

The process cannot access the file because it is being used by another process. XML

2 Answers2