AsyncFileAppender.cs

using log4net;
using log4net.Appender;
using log4net.Core;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;


 /// <summary>
    ///   <logger name="position">
    ///     <level value="DEBUG" />
    ///     <appender-ref ref="TESTLogger" />
    ///   </logger>
    ///   <appender name="TESTLogger" type="namespace.AsyncFileAppender">
    ///     <lockingModel type="log4net.Appender.FileAppender+MinimalLock"/>
    ///     <file value="Log\position.txt"/>
    ///     <appendToFile value="true"/>
    ///     <rollingStyle value="Date"/>
    ///     <datePattern value="yyyyMMdd"/>
    ///     <maxSizeRollBackups value="10"/>
    ///     <layout type="log4net.Layout.PatternLayout">
    ///       <conversionPattern value="%d{MM.dd.yyyy HH:mm:ss.fff} [%-5level] %logger // %message%newline"/>
    ///     </layout>
    ///     <filter type="log4net.Filter.LevelRangeFilter">
    ///       <levelMin value="ALL"/>
    ///       <acceptOnMatch value="true"/>
    ///     </filter>
    ///     <filter type="log4net.Filter.DenyAllFilter"/>
    ///   </appender>
    /// </summary>
    public class AsyncFileAppender : RollingFileAppender
    {
        const int RUNNING = 1;
        const int NOT_RUNNING = 0;
        static int runningState = 0;
        static readonly object syncLock = new object();
        static ConcurrentBag<AsyncFileAppender> afAppenders = new ConcurrentBag<AsyncFileAppender>();
        //static System.Collections.Queue logQueue = System.Collections.Queue.Synchronized(new System.Collections.Queue(1000, 1));
        static System.Threading.AutoResetEvent mAutoResetEvent = new System.Threading.AutoResetEvent(true);

        static int waitTime = 5 * 1000;

        object lockObject = new object();
        List<LoggingEvent> loggingEvents = new List<LoggingEvent>();

        /// <summary>
        /// Thread wait time (ms)
        /// </summary>
        public int WaitTime
        {
            get { return waitTime; }
            set
            {
                if (value > 0)
                {
                    waitTime = value;
                }
            }
        }
        public AsyncFileAppender()
            : base()
        {
            if (runningState == NOT_RUNNING) { processQueue(); }

            afAppenders.Add(this);
        }

        protected override void Append(log4net.Core.LoggingEvent loggingEvent)
        {
            if (runningState == NOT_RUNNING) { return; }
            lock (this.lockObject)
            {
                this.loggingEvents.Add(loggingEvent);//.DoAppend(tuple.Item2);
            }
        }

        static void processQueue()
        {
            //if (running == 1) { return; } System.Threading.Interlocked.Exchange(ref running, 1); // prevent double
            if (System.Threading.Interlocked.Exchange(ref runningState, RUNNING) == RUNNING) { return; } // prevent double

            new System.Threading.Thread(() =>
            {
                try
                {
                    System.Threading.Thread.CurrentThread.Priority = System.Threading.ThreadPriority.Lowest;
                    System.Threading.Thread.Sleep(300); // wait for first run delay
                    while (runningState == RUNNING)
                    {
                        writeLogs();
                        mAutoResetEvent.WaitOne(waitTime);
                    }
                }
                catch (System.Threading.ThreadInterruptedException ex)
                {
                }
                catch (System.Threading.ThreadAbortException ex)
                {
                }
            }).Start();

        }
        static void writeLogs()
        {
            foreach (var appKV in afAppenders)
            {
                if (appKV.loggingEvents.Count > 0)
                {
                    lock (appKV.lockObject)
                    {
                        appKV.AddToBaseAppender(appKV.loggingEvents.ToArray());
                        appKV.loggingEvents.Clear();
                    }
                }
            }
        }

        void AddToBaseAppender(LoggingEvent[] e)
        {
            base.Append(e);
        }

        protected override void OnClose()
        {
            mAutoResetEvent.Set();
            runningState = 0;// false;
            base.OnClose();
        }
    }