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C# error propagating up the stack when it should not

I'm encountering an issue where a service is exiting on errors that should never propagate up.
I built a microservice manager (.NET as the local environment doesnt support .NET Core and some of its native microservice abilities)
Built in VS2019 targeting .NET 4.5.2 (I know, but this is the world we live in)
For the microservice manager, it is built and installed as a windows service. Entry looks like this (#if/#else was for testing locally, it is working as intended when registered as a windows service)
Program.cs (Entry point)
` static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
static void Main()
{
#if DEBUG
Scheduler myScheduler = new Scheduler();
myScheduler.OnDebug();
System.Threading.Thread.Sleep(System.Threading.Timeout.Infinite);
#else
ServiceBase[] ServicesToRun;
ServicesToRun = new ServiceBase[]
{
new Scheduler()
};
ServiceBase.Run(ServicesToRun);
#endif
}
}`
Scheduler.cs
//(confidential code hidden)
`private static readonly Configuration config = Newtonsoft.Json.JsonConvert.DeserializeObject<Configuration>(
File.ReadAllText(configFilePath)
);
public Scheduler()
{
//InitializeComponent(); //windows service, doesnt need UI components initialized
}
public void OnDebug()
{
OnStart(null); //triggers when developing locally
}
protected override async void OnStart(string[] args)
{
try
{
logger.Log($#"Service manager starting...");
logger.Log($#"Finding external services... {config.services.Count} services found.");
foreach (var service in config.services)
{
try
{
if (service.disabled)
{
logger.Log(
$#"Skipping {service.name}: disabled=true in Data Transport Service's appSettings.json file");
continue;
}
logger.Queue($#"Starting: {service.name}...");
string serviceLocation = service.useRelativePath
? Path.Combine(assemblyLocation, service.path)
: service.path;
var svc = Assembly.LoadFrom(serviceLocation);
var assemblyType = svc.GetType($#"{svc.GetName().Name}.Program");
var methodInfo = assemblyType.GetMethod("Main");
var instanceObject = Activator.CreateInstance(assemblyType, new object[0]);
methodInfo.Invoke(instanceObject, new object[0]);
logger.Queue(" Running").Send("");
}
catch (TargetInvocationException ex)
{
logger.Queue(" Failed").Send("");
logger.Log("an error occurred", LOG.LEVEL.CRITICAL, ex);
}
catch (Exception ex)
{
logger.Queue(" Failed").Send("");
logger.Log("an error occurred", LOG.LEVEL.CRITICAL, ex);
}
}
logger.Log("Finished loading services.");
}
catch (Exception ex)
{
logger.Log($#"Critical error encountered", LOG.LEVEL.CRITICAL, ex);
}
}
Microservice:
public [Confidential]()
{
if (currentProfile == null)
{
var errMsg =
$#"Service not loaded, Profile not found, check appSettings.currentProfile: '{config.currentProfile}'";
logger.Log(errMsg,severity: LOG.LEVEL.CRITICAL);
throw new SettingsPropertyNotFoundException(errMsg);
}
if (currentProfile.disabled)
{
var errMsg = $#"Service not loaded: {config.serviceName}, Service's appSettings.currentProfile.disabled=true";
logger.Log(errMsg,LOG.LEVEL.WARN);
throw new ArgumentException(errMsg);
}
logger.Log($#"Loading: '{config.serviceName}' with following configuration:{Environment.NewLine}{JsonConvert.SerializeObject(currentProfile,Formatting.Indented)}");
logger.Queue($#"Encrypting config file passwords...");
bool updateConfig = false;
foreach (var kafkaSource in config.dataTargets)
{
if (!kafkaSource.password.IsEncrypted())
{
updateConfig = true;
logger.Queue($#"%tabEncrypting: {kafkaSource.name}");
kafkaSource.password = kafkaSource.password.Encrypt();
}
else
{
logger.Queue($#"%tabAlready encrypted: {kafkaSource.name}");
}
}
logger.Send(Environment.NewLine);
if (updateConfig)
{
File.WriteAllText(
configFilePath,
Newtonsoft.Json.JsonConvert.SerializeObject(config));
}
var _source = config.dataSources.FirstOrDefault(x=>x.name==currentProfile.dataSource);
var _target = config.dataTargets.FirstOrDefault(x => x.name == currentProfile.dataTarget);
source = new Connectors.Sql(logger,
_source?.name,
_source?.connectionString,
_source.pollingInterval,
_source.maxRowsPerSelect,
_source.maxRowsPerUpdate);
target = new Connectors.KafkaProducer(logger)
{
bootstrapServers = _target?.bootstrapServers,
name = _target?.name,
password = _target?.password.Decrypt(),
sslCaLocation = Path.Combine(assemblyLocation,_target?.sslCaLocation),
topic = _target?.topic,
username = _target?.username
};
Start();
}
public void Start()
{
Timer timer = new Timer();
try
{
logger.Log($#"SQL polling interval: {source.pollingInterval} seconds");
timer.Interval = source.pollingInterval * 1000;
timer.Elapsed += new ElapsedEventHandler(this.OnTimer);
timer.Start();
if (currentProfile.executeOnStartup)
Run();
}
catch (Exception ex)
{
var sb = new StringBuilder();
sb.AppendLine($#"Critical error encountered loading external service: {config.serviceName}.");
if (!timer.Enabled)
sb.AppendLine($#"service unloaded - Schedule not started!");
else
sb.AppendLine($#"service appears to be loaded and running on schedule.");
logger.Log(sb.ToString(), LOG.LEVEL.CRITICAL, ex);
}
}
public void OnTimer(object sender, ElapsedEventArgs e)
{
try
{
Run();
}
catch (Exception ex)
{
logger.Log($#"Critical error during scheduled run on service: {config.serviceName}.", LOG.LEVEL.CRITICAL, ex);
}
}
public async void Run()
{
//Get new alarm events from SQL source
logger.Queue("Looking for new alarms...");
var rows = await GetNewEvents();`
The exception occurred during the GetNewEvents method, which attempted to open a SqlConnection to a SQL server that was unavailable due to network issues, that method intentionally throws an exception, which should throw up to OnTimer, where it gets caught, logged, and the timer keeps running. During development/testing, I used invalid credentials, bad connection string, etc and simulated this type of error and it worked as expected, logged the error, kept running. For some reason recently, that error is not caught in OnTimer, it propagates up, where it should be caught by Start (but isn't), after that it should be caught by the parent service manager which is entirely wrapped in a try/catch with no throw's, and above that (because their could be multiple microservices managed by that service) the entry point to the service manager is wrapped in try/catch with no throws, all for isolation from microservice errors. For some reason though, now, the error from a VERY downstream application is propagating all the way up.
Typically, this code runs 24/7 no issues, the microservice it is loading from the config file launches and runs fine. The entry into that specific microservice starts with a try {...} catch (Exception ex) {...} block.
The concept is to have a microservice manager than can launch a number of microservices without having to install all of them as windows services, and have some level of configuration driven by a config file that dictates how the main service runs.
The microservice represented here opens a SQL connection, reads data, performs business logic, publishes results to Kafka, it does this on a polling interval dictated by the config file contained in the microservice. As stated above, its ran for months without issue.
Recently, I noticed the main microservice manager service was not running on the windows server, I investigated the Server Application Logs and found a "Runtime Error" that essentially stated the microservice, while attempting to connect to sql, failed (network issue) and caused the entire microservice manager to exit. To my understanding, they way I'm launching the microservice should isolate it from the main service manager app. Additionally, the main service manager app is wrapped in a very generic try catch block. The entry point to the micro service itself is wrapped in a try catch, and almost every component in the microservice is wrapped in try / catch per business need. The scenario that faulted (cant connect to sql) intentionally throws an error for logging purposes, but should be caught by the immediate parent try/catch, which does not propagate or re-throw, only logs the error to a txt file and the windows server app log.
How is it that this exception is bubbling up through isolation points and causing the main service to fault and exit? I tested this extensively during development and prior to release, this exact scenario being unable to connect to sql, and it generated the correct log entry, and tried again on the next polling cycle as expected.
I haven't tried any other approaches as yet, as I feel they would be band-aid fixes as best as I dont understand why the original design is suddenly failing. The server hasn't changed, no patching/security updates/etc.
From the server Application Log:
Application: DataTransportService.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Exception
at Connectors.SqlHelper.DbHelper+d__13`1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].MoveNext()
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(System.Threading.Tasks.Task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(System.Threading.Tasks.Task)
at IntelligentAlarms.IntelligentAlarm+d__14.MoveNext()
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(System.Threading.Tasks.Task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(System.Threading.Tasks.Task)
at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(System.Threading.Tasks.Task)
at IntelligentAlarms.IntelligentAlarm+d__12.MoveNext()
at System.Runtime.CompilerServices.AsyncMethodBuilderCore+<>c.b__6_1(System.Object)
at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(System.Object)
at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
at System.Threading.ThreadPoolWorkQueue.Dispatch()
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()

WindowsService FileSystemWatcher Crash on InputOnChanged call

I have a Windows Service that I successfully deploys, successfully works when debugging, but crashes when a file is added to the monitored directory.
I thought it was an issue with my impersonator being used between the OnStart and InputOnChanged, but the crash still happens when I run the service under my own domain user.
I have EventLog set to write to it's own application source, but none of my WriteEntrys are called except the one in the OnStart function. I've been trying different tweaks and feel like I need another set of eyes to see something i'm not:
protected override void OnStart(string[] args)
{
//using(Impersonator context = new Impersonator("XXXXX", "XXXXXXXX", "XXXXXXXXXX"))
//{
try
{
this.fileWatcherService = new FileSystemWatcher(baseFilePath, "*.txt")
{
NotifyFilter = NotifyFilters.LastWrite
};
fileWatcherService.Changed += InputOnChanged;
fileWatcherService.EnableRaisingEvents = true;
eventLog.WriteEntry("XXXX-XXXXX-Service Started");
}
catch (Exception ex)
{
eventLog.WriteEntry($"{baseFilePath} was not accessible to monitor because {ex.Message}", EventLogEntryType.Error);
}
}
protected void InputOnChanged(object source, FileSystemEventArgs e)
{
if (e.ChangeType == WatcherChangeTypes.Changed)
{
eventLog.WriteEntry($"Change Detected - File {e.Name}", EventLogEntryType.Information);
try
{
fileWatcherService.EnableRaisingEvents = false;
eventLog.WriteEntry("Starting process for file: " + e.Name);
if (!File.Exists(e.FullPath))
{
eventLog.WriteEntry($"{e.Name} was not accessible", EventLogEntryType.Error);
}
//Copy File to backup copy before formatting
File.Copy(e.FullPath
, Path.Combine(#"\\XXXXXX\XXXXXX\XXXXXXXX\XXXXXXXXXX XXX XXXXXXXXX\XXX\XXXX\XXXX\BackupFiles", GetBackupFileName(e.Name))
, false);
//Save formatted file to directory
List<string> lines = System.IO.File.ReadAllLines(e.FullPath).ToList();
File.WriteAllText(Path.Combine(#"\\XXXXXX\XXXXXX\XXXXXXXX\XXXXXXXXXX XXX XXXXXXXXX\XXX\XXXX\XXXX\FormattedFiles", GetFormattedFileName(e.Name))
, CSVFormatService.FormatLines(lines));
//Remove file from base path to prevent re-processing
File.Delete(e.FullPath);
eventLog.WriteEntry($"Successfully moved {e.FullPath}", EventLogEntryType.Information);
}
catch (Exception ex)
{
eventLog.WriteEntry("XXXX-XXXXX-Service exception: " + ex.Message, EventLogEntryType.Error);
}
finally
{
fileWatcherService.EnableRaisingEvents = true;
}
}
}
Would expect eventLog.WriteEntry("Starting process for file: " + e.Name); to update the Application log at least because that is before any attempt to touch a file, but I don't see that in the log. However, the service runs until I place a test file in the monitored directory, and then crashes with a unhandled exception of file does not exist

When building out these services, make sure you reference a shared project correctly. This issue was caused by adding a reference to a class library to the project, but the .dll was missing when deploying the service. So when the service tried to access the .dll to process data a FileNotFound exception was being thrown. This also make sense as to why the exception was marked as unhandled.

Error Logging in C# Website

I am planning to implement error logging writing something similar to this:
public static void WriteError(string errorMessage)
{
try
{
string path = "~/Error/" + DateTime.Today.ToString("dd-mm-yy") + ".txt";
if (!File.Exists(System.Web.HttpContext.Current.Server.MapPath(path)))
{
File.Create(System.Web.HttpContext.Current.Server.MapPath(path)).Close();
}
using (StreamWriter w = File.AppendText(System.Web.HttpContext.Current.Server.MapPath(path)))
{
w.WriteLine("\r\nLog Entry : ");
w.WriteLine("{0}", DateTime.Now.ToString(CultureInfo.InvariantCulture));
string err = "Error in: " + System.Web.HttpContext.Current.Request.Url.ToString() +
". Error Message:" + errorMessage;
w.WriteLine(err);
w.WriteLine("__________________________");
w.Flush();
w.Close();
}
}
catch (Exception ex)
{
WriteError(ex.Message);
}
}
My question is this: Since it is a website, I will have multiple users simultaneously. In that case, if multiple users encounter exceptions at the same time and try to write to the same file, it will again give me an exception right? In that case, how do I implement error logging correctly for simultaneous users? Or will this work?
Thanks in advance.

I'd recommend you use an established logging framework such as NLog or log4net. I have used log4net on many projects in the past and it handles this scenario perfectly.
EDIT:
Just as a further comment, as well as handling log messages from multiple threads log4net also allows you to manage how large your log files grow and provide a built in rolling log mechanism via the RollingFileAppender.

Beside using NLog or other log library, the way you lock this cases is with mutex. I suggest mutex, and not lock() because can catch all pools/threads that may throw an error.
On MSDN there are the details about mutex and examples:
http://msdn.microsoft.com/en-us/library/system.threading.mutex.aspx
a simple example
public static void WriteError(string errorMessage)
{
var mut = new Mutex(true, "LogMutexName");
try
{
// Wait until it is safe to enter.
mut.WaitOne();
// here you open write close your file
}
finally
{
// Release the Mutex.
mut.ReleaseMutex();
}
}

How to delete a shared folder using c# code if the directory is opened on another machine?

I'm trying to delete an empty shared directory which is opened in another machine.
If i directly delete the directory(right click and delete) it is removed.
Stopwatch st = new Stopwatch();
st.Start();
while(true){
try
{
Directory.Delete(pathToDelete, true);
Console.WriteLine("Directory Deleted" + "Elapsed time:" + st.Elapsed.Seconds.ToString() + "sec");
break;
}
catch (Exception e)
{
if ((e is System.IO.IOException) || (e is System.UnauthorizedAccessException) ||
(e is System.Reflection.TargetInvocationException))
{
Console.WriteLine(e.ToString());
if (st.Elapsed > TimeSpan.FromMinutes(5))
{
Console.WriteLine("Can not delete directory ");
return;
}
Thread.Sleep(1000);
}
else
{
throw;
}
}
}
It is not deleting the directory if the directory opened on same machine or different machine using the shared-path.
I found this
but i couldn't understand the code properly.
Anyone suggest a better method?
Thanks in Advance

System.IO.IOException: The process cannot access the file 'c:\dir' because it is being used by another process
That means that its in use, therefore your not going to be able to remove it. If its empty like you say, then it must be either a) in use by someone on the Network Share or there's something running on the server that its ran from that's monitoring it. You may need to stop a service.

sporadic error while getting all messages in Windows messagequeue

In C# ASP.NET 3.5 web application running on Windows Server 2003, I get the following error once in a while:
"Object reference not set to an instance of an object.: at System.Messaging.Interop.MessagePropertyVariants.Unlock()
at System.Messaging.Message.Unlock()
at System.Messaging.MessageQueue.ReceiveCurrent(TimeSpan timeout, Int32 action, CursorHandle cursor, MessagePropertyFilter filter, MessageQueueTransaction internalTransaction, MessageQueueTransactionType transactionType)
at System.Messaging.MessageEnumerator.get_Current()
at System.Messaging.MessageQueue.GetAllMessages()".
The line of code that throws this error is:
Message[] msgs = Global.getOutputQueue(mode).GetAllMessages();
where Global.getOutputQueue(mode) gives the messagequeue I want to get messages from.
Update:
Global.getPool(mode).WaitOne();
commonClass.log(-1, "Acquired pool: " + mode, "Report ID: " + unique_report_id);
............../* some code /
..............
lock(getLock(mode))
{
bool yet_to_get = true;
int num_retry = 0;
do
{
try
{
msgs = Global.getOutputQueue(mode).GetAllMessages();
yet_to_get = false;
}
catch
{
Global.setOutputQueue(mode);
msgs = Global.getOutputQueue(mode).GetAllMessages();
yet_to_get = false;
}
++num_retry;
}
while (yet_to_get && num_retry < 2);
}
... / some code*/
....
finally
{
commonClass.log(-1, "Released pool: " + mode, "Report ID: " + unique_report_id);
Global.getPool(mode).Release();
}

Your description and this thread suggests a timing issue. I would create the MessageQueue object infrequently (maybe only once) and have Global.getOutputQueue(mode) return a cached version, seems likely to get around this.
EDIT: Further details suggest you have the opposite problem. I suggest encapsulating access to the message queue, catching this exception and recreating the queue if that exception occurs. So, replace the call to Global.getOutputQueue(mode).GetAllMessages() with something like this:
public void getAllOutputQueueMessages()
{
try
{
return queue_.GetAllMessages();
}
catch (Exception)
{
queue_ = OpenQueue();
return queue_.GetAllMessages();
}
}
You'll notice I did not preserve your mode functionality, but you get the idea. Of course, you have to duplicate this pattern for other calls you make to the queue, but only for the ones you make (not the whole queue interface).

This is an old thread, but google brought me here so I shall add my findings.
I agree with user: tallseth that this is a timing issue.
After the message queue is created it is not instantly available.
try
{
return _queue.GetAllMessages().Length;
}
catch (Exception)
{
System.Threading.Thread.Sleep(4000);
return _queue.GetAllMessages().Length;
}
try adding a pause if you catch an exception when accessing a queue which you know has been created.
On a related note
_logQueuePath = logQueuePath.StartsWith(#".\") ? logQueuePath : #".\" + logQueuePath;
_queue = new MessageQueue(_logQueuePath);
MessageQueue.Create(_logQueuePath);
bool exists = MessageQueue.Exists(_logQueuePath);
running the MessageQueue.Exists(string nameofQ); method immediately after creating the queue will return false. So be careful when calling code such as:
public void CreateQueue()
{
if (!MessageQueue.Exists(_logQueuePath))
{
MessageQueue.Create(_logQueuePath);
}
}
As it is likely to throw an exception stating that the queue you are trying to create already exists.
-edit: (Sorry I don't have the relevant link for this new info)
I read that a newly created MessageQueue will return false on MessageQueue.Exists(QueuePath)until it has received at least one message.
Keeping this and the earlier points i mentioned in mind has gotten my code running reliably.