反复读取小文件会抛出OutOfMemory

Question

I have two programs that work together. To coordinate their operations I use a small settings file. This setting file contains two words separated by a ';'. So in the one program I repeatedly read the words in the file using a while loop. By repeatedly I mean once every second. The loop only terminates when the program terminates; when the user turns off the pc.

But with each iteration of the loop the program size in memory increases until the program throws an OutOfMemory exception. I have tried two different methods of reading the files but both causes the program to 'grow' in memory.

FileStream FS = new FileStream("br.stat", FileMode.Open);
StreamReader SR = new StreamReader(FS);
string s = SR.ReadToEnd();
FS.Dispose();
SR.Dispose();

and

string S = File.ReadAllText("br.stat");

Is there a way to read a file repeatedly with out this happening?

Thanks.

Answer 1

the problem is the design, more so than the implementation. You only need to read from the file once when the app starts and again when the file changes. You can use FileSystemWatcher to detect changes to the file and reload the settings.

This uses drastically less resources than reading the file indefinitely.

also, you'll want to take advantage of the using keyword to ensure you properly dispose of the file stream and reader. In fact I would simplify and just use File.ReadAllText(filename) .

Answer 2

I think you're doing it wrong. Realistically there is no need to read the file every iteration unless its changed.

Instead it would be better to use a FileSystemWatcher http://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher.changed(v=vs.85).aspx to read the values and change your control values.

You should also use the following to circumvent your memory leak issues

using (var FS = new FileStream("br.stat", FileMode.Open))
{
    using (var SR = new StreamReader(FS))
    {
        var s = SR.ReadToEnd();
    }
}

Answer 3

I would recomend you look at using an using statement

File and Font are examples of managed types that access unmanaged resources (in this case file handles and device contexts). There are many other kinds of unmanaged resources and class library types that encapsulate them. All such types must implement the IDisposable interface.

As a rule, when you use an IDisposable object, you should declare and instantiate it in a using statement. The using statement calls the Dispose method on the object in the correct way, and (when you use it as shown earlier) it also causes the object itself to go out of scope as soon as Dispose is called. Within the using block, the object is read-only and cannot be modified or reassigned.

so something like

using (FileStream FS = new FileStream("br.stat", FileMode.Open))
using (StreamReader SR = new StreamReader(FS))
{
    string s = SR.ReadToEnd();
}