.NET 2.0 : File.AppendAllText(...) - Thread safe implementation

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As an exercise in idle curiosity more than anything else, consider the following simple logging class:

internal static class Logging
{
    private static object threadlock;

    static Logging()
    {
        threadlock = new object(); 
    }

    internal static void WriteLog(string message)
    {
        try
        {
            lock (threadlock)
            {
                File.AppendAllText(@"C:\logfile.log", message);
            }
        }
        catch
        {
            ...handle logging errors...
        }
    }
}

Is the lock needed around File.AppendAllText(...) or is the method inherently thread-safe by its own implementation ?

Searching for information on this yields a lot of contradictory information, some say yes, some say no. MSDN says nothing.


File.AppendAllText is going to acquire an exclusive write-lock on the log file, which would cause any concurrent thread attempting to access the file to throw an exception. So yes, you need a static lock object to prevent multiple threads from trying to write to the log file at the same time and raising an IOException.

If this is going to be an issue, I'd really suggest logging to a database table which will do a better job of handling concurrent log writers.

Alternatively, you can use TextWriterTraceListener which is thread-safe (well, it's going to do the locking for you; I'd rather write as little of my own multithreaded code as possible).

Writing to file in a thread safe manner, 2 Answers. 2. order by You'll be assured that there are no conflicts with other threads in your program. If you want ToString());. Assuming you're using .NET 4.0 or later. See File.AppendAllText. file paths. For example: File.AppendAllText is going to acquire an exclusive write-lock on the log file, which would cause any concurrent thread attempting to access the file to throw an exception. So yes, you need a static lock object to prevent multiple threads from trying to write to the log file at the same time and raising an IOException .


Testing parallel writes shows that you would get a System.IO.IOException if you were to comment out your lock statement.

[Test]
public void Answer_Question()
{
    var ex = Assert.Throws<AggregateException>(() => Parallel.Invoke(
        () => Logging.WriteLog("abc"),
        () => Logging.WriteLog("123")
    ));

    // System.IO.IOException: The process cannot access the file 'C:\Logs\thread-safety-test.txt' because it is being used by another process.
    Console.Write(ex);
}

NET 2.0 : File.AppendAllText() - Thread safe implementation, As an exercise in idle curiosity more than anything else, consider the following simple logging class:internal static class Logging{ private static object threadlock;​  Question. Does File.AppendAllText manage collisions from multiple writers?. Research. I noticed that the MSDN documentation doesn't really provide a position either way, so I decided I'd reflect the code and just see what it does.


It is thread safe in the sense that it opens the file with Read sharing, so assuming your filesystem honors file locks, only one thread will be allowed to write to the file at a time. Other threads may, however, get dirty reads if they are attempting to read the same file.

Writing to file in a thread safe manner, NET 2.0 : File.AppendAllText() - Thread safe implementation. Question. As an exercise in idle curiosity more than anything else, consider the following simple  Adding locks to create thread-safe code decreases performance, increases lock contention, and creates the possibility for deadlocks to occur. In common application models, only one thread at a time executes user code, which minimizes the need for thread safety. For this reason, the .NET Framework class libraries are not thread safe by default.


File Locking in a Multi Threaded Environment, or is the method inherently thread-safe by its own implementation ? File.​AppendAllText is going to acquire an exclusive write-lock on the log  There are a lot of introductory articles to multithreading for .NET 2.0 and, I have to say, they have helped me a lot. What I have used is the BackgroundWorker .NET 2.0 component (but there are code implementations for it on .NET 1.1 that do the job. Here I put some links to these articles: Good introductory article from Paul Kimmel


[Solved] Thread-safe acces to a text file., I'm not sure why this is async. Unless you have a good reason for write to the file asynchronously, this is wasted effort. If you lock properly, this  I need to determine the version of SQL Server (2000, 2005 or 2008 in this particular case) that a connection string connects a C# console application (.NET 2.0). Can anyone provide any guidance on


Thread Safe File Write C#, We need to write to a file and make sure it is safe: In normal C# development, we use the lock keyword to implement a A Dictionary<> is not thread safe so we need to use ConcurrentDictionary<> instead hardware and software changes he eventually came across .net and John Brett7-Jun-17 2:36. c# collections properties thread-safety. improve this question. edited Jun 2 '12 at 4:28. 41 silver badges. 57 bronze badges. asked May 3 '11 at 19:01. 121 silver badges. 188 bronze badges. use locks, that should do it. – atoMerz May 3 '11 at 19:05. Can use use a thread-safe implementation of IList<T> (vs List<T> )? – Greg May 3 '11 at 19:13.