Listens to the event log to detect when app pool recycle events are triggered (IIS must be configured to write these to the logs)

App Pool Recycle Listener.cs

using System;
using System.Diagnostics;
using System.Net;

namespace EventLogListener
{
    class Program
    {
        static void Main(string[] args)
        {
            var listener = new ApplicationPoolRecycleListener("StreamingServer")
            {
                OnTargetApplicationRecycled = (entry, recycleReason) =>
                {
                    // do something
                    return true;
                },

                OnNonTargetApplicationRecycled = (entry, recycleReason) =>
                {
                    // do something
                    return true;
                }
            };

            listener.StartListening();
        }
    }

    public class ApplicationPoolRecycleListener
    {
        public enum RecycleReason
        {
            IisReset = 3202,
            ReachedProcessingTimeLimit = 5074,
            ReachedAllowedRequestLimit = 5075,
            ReachedScheduledRecycleTime = 5076,
            ReachedVirtualMemoryLimit = 5077,
            ReachedPrivateBytesMemoryLimit = 5117,
            AdministratorRequest = 5079,
            AppPoolConfigurationChange = 5080,
            IisConfigurationError = 5081
        }

        private readonly string _targetApplicationPoolName;
        private bool _stopListening;

        public Func<EntryWrittenEventArgs, RecycleReason, bool> OnTargetApplicationRecycled { get; set; }
        public Func<EntryWrittenEventArgs, RecycleReason, bool> OnNonTargetApplicationRecycled { get; set; }

        public ApplicationPoolRecycleListener(string targetApplicationPoolName)
        {
            _targetApplicationPoolName = targetApplicationPoolName;
            _stopListening = false;
        }

        public void StartListening()
        {
            var eventLog = new EventLog { Log = "System", EnableRaisingEvents = true };
            eventLog.EntryWritten += EventWrittenCallback;

            var eventLog2 = new EventLog { Log = "Application", EnableRaisingEvents = true };
            eventLog2.EntryWritten += EventWrittenCallback;
            while (_stopListening == false) { }
        }

        private void EventWrittenCallback(object sender, EntryWrittenEventArgs e)
        {
            var eventId = e.Entry.EventID;

            if (Enum.IsDefined(typeof (RecycleReason), eventId))
            {
                var recycleReason = (RecycleReason)eventId;

                if (recycleReason == RecycleReason.IisReset)
                {
                    _stopListening = OnTargetApplicationRecycled?.Invoke(e, recycleReason) ?? false;
                }
                else
                {
                    if (e.Entry.Message.ToLower().Contains($"serving application pool '{_targetApplicationPoolName.ToLower()}'"))
                    {
                        _stopListening = OnTargetApplicationRecycled?.Invoke(e, recycleReason) ?? false;
                    }
                    else
                    {
                        _stopListening = OnNonTargetApplicationRecycled?.Invoke(e, recycleReason) ?? false;
                    }
                }
            }
        }
    }
}