HI all.

We are getting 3 errors when using a custom IComponent running a BackgroundTaskRunner with a task inherited by RecurringTaskBase and a custom email service, that i dunno how to work around.

IComponent

public class ScheduleTaskCompontent : IComponent
{
    private readonly ILogger _logger;
    private readonly IEmailTaskService _emailTaskService;
    private BackgroundTaskRunner<IBackgroundTask> _tasksRunner;

    public ScheduleTaskCompontent(ILogger logger, IEmailTaskService emailTaskService)
    {
        _logger = logger;
        _emailTaskService = emailTaskService;
    }

    public void Initialize()
    {
        _tasksRunner = new BackgroundTaskRunner<IBackgroundTask>("ScheduleTasks", _logger);
        var sendOutTask = new SendOutTask(_tasksRunner, 5000, 30000, _logger, _emailTaskService);
        _tasksRunner.Add(sendOutTask);
    }

    public void Terminate()
    {

    }
}

RecurringTaskBase

public class SendOutTask : RecurringTaskBase
{
    private readonly ILogger _logger;
    private readonly IEmailTaskService _emailTaskService;

    public override bool IsAsync => true;

    public override bool RunsOnShutdown => false;

    public SendOutTask(IBackgroundTaskRunner<RecurringTaskBase> runner, int delayMilliseconds, int periodMilliseconds, ILogger logger, IEmailTaskService emailTaskService) : base(runner, delayMilliseconds, periodMilliseconds)
    {
        _logger = logger;
        _emailTaskService = emailTaskService;
    }

    public override Task<bool> PerformRunAsync(CancellationToken token)
    {
        try
        {
            _emailTaskService.SendEmails(4);
            _logger.Info<SendOutTask>("ScheduleTask[SendOut] OK!");
        }
        catch (Exception ex)
        {
            _logger.Error<SendOutTask>(ex, "ScheduleTask[SendOut] ERROR!");
        }

        return Task.FromResult<bool>(true);
    }
}

IEmailTaskService

public class EmailTaskService : IEmailTaskService
{
    private readonly IScopeProvider _scopeProvider;
    private readonly ILogger _logger;
    private readonly IHostingEnvironmentService _hostingEnvironmentService;
    private readonly IFileService _fileService;

    public EmailTaskService(IScopeProvider scopeProvider, ILogger logger, IHostingEnvironmentService hostingEnvironmentService, IFileService fileService)
    {
        _scopeProvider = scopeProvider;
        _logger = logger;
        _hostingEnvironmentService = hostingEnvironmentService;
        _fileService = fileService;
    }

    public void SendEmails(int take = 30)
    {
        using (var scope = _scopeProvider.CreateScope(autoComplete: true))
        {
            var sql = Sql.Builder.Select("*").From(TableInfo.FromPoco(typeof(EmailTask)).TableName).Where("bounces < 4").OrderBy("id");
            var allMails = scope.Database.Fetch<EmailTask>(sql);
            if (allMails != null && allMails.Any())
            {
                using (var client = new SmtpClient())
                {
                    foreach (var mail in allMails.Take(take))
                    {
                        var isSuccess = false;

                        try
                        {
                            using (var mailMessage = new MailMessage()
                            {
                                IsBodyHtml = true,
                                BodyEncoding = Encoding.UTF8,
                                HeadersEncoding = Encoding.UTF8,
                                SubjectEncoding = Encoding.UTF8,
                                Priority = MailPriority.High,
                                BodyTransferEncoding = System.Net.Mime.TransferEncoding.Base64,
                                Subject = mail.Subject,
                                Body = mail.Body,
                                From = new MailAddress(mail.SenderEmail, !string.IsNullOrEmpty(mail.SenderName) ? mail.SenderName : mail.SenderEmail, Encoding.UTF8)
                            })
                            {
                                mailMessage.To.Add(mail.ReceiverEmails);

                                if (!string.IsNullOrEmpty(mail.Bcc))
                                {
                                    mailMessage.Bcc.Add(mail.Bcc);
                                }

                                if (!string.IsNullOrEmpty(mail.Cc))
                                {
                                    mailMessage.CC.Add(mail.Cc);
                                }

                                if (!string.IsNullOrEmpty(mail.Files))
                                {
                                    var files = mail.Files.Split(',');
                                    foreach (var file in files)
                                    {


                                        mailMessage.Attachments.Add(new Attachment(_hostingEnvironmentService.MapPath(file.Trim())));
                                    }
                                }

                                client.Send(mailMessage);

                                isSuccess = true;
                            }
                        }
                        catch (Exception ex)
                        {
                            mail.SentDate = DateTime.Now;
                            mail.Bounces = mail.Bounces + 1;
                            mail.ErrorMessage = ex.Message;
                            isSuccess = false;
                        }

                        if (isSuccess)
                        {
                            var mailId = mail.Id;
                            scope.Database.Delete<EmailTask>(mail);
                            _fileService.DeleteFromEmails(mailId.ToString());
                        }
                        else
                        {
                            scope.Database.Update(mail);
                        }
                    }
                }
            }
        }
    }
}

The first error is:

System.Data.SqlClient.SqlException (0x80131904): Execution Timeout Expired.  The timeout period elapsed prior to completion of the operation or the server is not responding. ---> System.ComponentModel.Win32Exception (0x80004005): The wait operation timed out
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParserStateObject.ReadSniError(TdsParserStateObject stateObj, UInt32 error)
   at System.Data.SqlClient.TdsParserStateObject.ReadSniSyncOverAsync()
   at System.Data.SqlClient.TdsParserStateObject.TryReadNetworkPacket()
   at System.Data.SqlClient.TdsParserStateObject.TryPrepareBuffer()
   at System.Data.SqlClient.TdsParserStateObject.TryReadByte(Byte& value)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
   at System.Data.SqlClient.TdsParser.TdsExecuteTransactionManagerRequest(Byte[] buffer, TransactionManagerRequestType request, String transactionName, TransactionManagerIsolationLevel isoLevel, Int32 timeout, SqlInternalTransaction transaction, TdsParserStateObject stateObj, Boolean isDelegateControlRequest)
   at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransactionYukon(TransactionRequest transactionRequest, String transactionName, IsolationLevel iso, SqlInternalTransaction internalTransaction, Boolean isDelegateControlRequest)
   at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransaction(TransactionRequest transactionRequest, String name, IsolationLevel iso, SqlInternalTransaction internalTransaction, Boolean isDelegateControlRequest)
   at System.Data.SqlClient.SqlInternalConnection.BeginSqlTransaction(IsolationLevel iso, String transactionName, Boolean shouldReconnect)
   at System.Data.SqlClient.SqlConnection.BeginTransaction(IsolationLevel iso, String transactionName)
   at System.Data.SqlClient.SqlConnection.BeginDbTransaction(IsolationLevel isolationLevel)
   at System.Data.Common.DbConnection.BeginTransaction(IsolationLevel isolationLevel)
   at StackExchange.Profiling.Data.ProfiledDbConnection.BeginDbTransaction(IsolationLevel isolationLevel) in C:\projects\dotnet\src\MiniProfiler.Shared\Data\ProfiledDbConnection.cs:line 138
   at System.Data.Common.DbConnection.BeginTransaction(IsolationLevel isolationLevel)
   at Umbraco.Core.Persistence.FaultHandling.RetryDbConnection.BeginDbTransaction(IsolationLevel isolationLevel) in D:\a\1\s\src\Umbraco.Core\Persistence\FaultHandling\RetryDbConnection.cs:line 30
   at System.Data.Common.DbConnection.BeginTransaction(IsolationLevel isolationLevel)
   at NPoco.Database.BeginTransaction(IsolationLevel isolationLevel)
   at Umbraco.Core.Scoping.Scope.get_Database() in D:\a\1\s\src\Umbraco.Core\Scoping\Scope.cs:line 242
   at XXX.Core.Services.EmailTaskService.SendEmails(Int32 take) in ...\XXX.Core\Services\EmailTaskService.cs:line 78
   at XXX.Core.RecurringTasks.SendOutTask.PerformRunAsync(CancellationToken token) in ...\XXX.Core\RecurringTasks\SendOutTask.cs:line 29
ClientConnectionId:3017f3e2-98c7-4fdd-a972-b938ba61b933
Error Number:-2,State:0,Class:11

The second error is:

System.InvalidOperationException: Timeout expired.  The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached.
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at NPoco.Database.OpenSharedConnectionImp(Boolean isInternal)
   at NPoco.Database.BeginTransaction(IsolationLevel isolationLevel)
   at Umbraco.Core.Scoping.Scope.get_Database() in D:\a\1\s\src\Umbraco.Core\Scoping\Scope.cs:line 242
   at Umbraco.Core.Scoping.Scope.WriteLock(Int32[] lockIds) in D:\a\1\s\src\Umbraco.Core\Scoping\Scope.cs:line 492
   at Umbraco.Core.Services.Implement.ServerRegistrationService.TouchServer(String serverAddress, String serverIdentity, TimeSpan staleTimeout) in D:\a\1\s\src\Umbraco.Core\Services\Implement\ServerRegistrationService.cs:line 50
   at Umbraco.Web.Compose.DatabaseServerRegistrarAndMessengerComponent.TouchServerTask.PerformRun() in D:\a\1\s\src\Umbraco.Web\Compose\DatabaseServerRegistrarAndMessengerComponent.cs:line 259

The third error is:

Failed (will repeat). from  Umbraco.Web.Compose.DatabaseServerRegistrarAndMessengerComponent+InstructionProcessTask

Most of the time the task works, but sometimes we get these errors.

Do anyone have a clue?

Should i close the scope earlier or send the work to other threads?