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Details: Written by: Stanko Milosev; Category: C#; Published: 23 February 2025; Last Updated: 25 February 2025; Hits: 634

Here is one my list of possibilities, how to update UI from Parallel.ForEach.

First, and probably the best with IProgress:

private readonly IProgress<int> _recordCountProgress;
private readonly IProgress<string> _fileNameProgress;
...
Parallel.ForEach(Directory.EnumerateFiles(path, "*.*", SearchOption.AllDirectories), options, fileName =>
{
	RecordCount = Interlocked.Increment(ref _recordCount);
	if (RecordCount % progressStep == 0)
	{
		_fileNameProgress.Report(fileName);
		_recordCountProgress.Report(RecordCount);
	}
});
...
IProgress<int> recordCountProgress = new Progress<int>(NumberOfFilesProcessedIProgress);
IProgress<string> fileNameProgress = new Progress<string>(FileProcessedIProgress);

notice:

	if (RecordCount % progressStep == 0)

If there are only few files _recordCount will be always 0, because it is to fast, if there are too many files, without UI would be blocked.

Second with SynchronizationContext:

Parallel.ForEach(Directory.EnumerateFiles(path, "*.*", SearchOption.AllDirectories), options, fileName =>
{
	RecordCount = Interlocked.Increment(ref _recordCount);
	if (RecordCount % progressStep == 0)
	{
			_syncContext?.Post(_ =>
			{
				FileProcessed?.Invoke(this,
					new FilesProcessedSynchronizationContextEventArgs(fileName));
				NumberOfFilesProcessed?.Invoke(this,
					new RecordCountSynchronizationContextEventArgs(_recordCount));
			}, null);
	}
});

Same as previous, problem with the line:

	if (RecordCount % progressStep == 0)

Third with System.Threading.Timer:

CancellationTokenSource = cancellationTokenSource;
_timer = new System.Threading.Timer(_ =>
{
	if (_queue.TryDequeue(out string? fileName))
	{
		if (form.InvokeRequired)
		{
			form.BeginInvoke(() =>
			{
				FileProcessed?.Invoke(this, new FilesProcessedEventArgs(fileName));
				NumberOfFilesProcessed?.Invoke(this, new RecordCountEventArgs(_recordCount));
			});
		}
		else
		{
			FileProcessed?.Invoke(this, new FilesProcessedEventArgs(fileName));
			NumberOfFilesProcessed?.Invoke(this, new RecordCountEventArgs(_recordCount));
		}
	}
}, null, 0, 100);

Example download from here

Details: Written by: Stanko Milosev; Category: C#; Published: 08 February 2025; Last Updated: 12 February 2025; Hits: 635

Here is my example first main part:

await using var sqlConnection = new SqlConnection(connectionString);
using var sqlBulkCopy = new SqlBulkCopy(sqlConnection);
using var csvDataReader = new CsvDataReader(csvPath);
await sqlConnection.OpenAsync();
sqlBulkCopy.DestinationTableName = "GpsInfo";
await sqlBulkCopy.WriteToServerAsync(csvDataReader);

Now IDataReader

using System.Data;

namespace SaveCsvFileToSqServerWithBulkCopy;

public class CsvDataReader: IDataReader
{
    private readonly StreamReader _reader;
    private string[]? _currentRow;
    private readonly string[]? _headers;

    public CsvDataReader(string filePath)
    {
        _reader = new StreamReader(filePath);
        _headers = _reader.ReadLine()?.Split(';');
    }

    public bool Read()
    {
        if (_reader.EndOfStream) return false;
        _currentRow = _reader.ReadLine()?.Split(';');
        return true;
    }

    public object GetValue(int i) => _currentRow[i];
    public int FieldCount => _headers.Length;
    public void Dispose() => _reader.Dispose();

    public bool GetBoolean(int i)
    {
        throw new NotImplementedException();
    }

    public byte GetByte(int i)
    {
        throw new NotImplementedException();
    }

    public long GetBytes(int i, long fieldOffset, byte[]? buffer, int bufferoffset, int length)
    {
        throw new NotImplementedException();
    }

    public char GetChar(int i)
    {
        throw new NotImplementedException();
    }

    public long GetChars(int i, long fieldoffset, char[]? buffer, int bufferoffset, int length)
    {
        throw new NotImplementedException();
    }

    public IDataReader GetData(int i)
    {
        throw new NotImplementedException();
    }

    public string GetDataTypeName(int i)
    {
        throw new NotImplementedException();
    }

    public DateTime GetDateTime(int i)
    {
        throw new NotImplementedException();
    }

    public decimal GetDecimal(int i)
    {
        throw new NotImplementedException();
    }

    public double GetDouble(int i)
    {
        throw new NotImplementedException();
    }

    public Type GetFieldType(int i)
    {
        throw new NotImplementedException();
    }

    public float GetFloat(int i)
    {
        throw new NotImplementedException();
    }

    public Guid GetGuid(int i)
    {
        throw new NotImplementedException();
    }

    public short GetInt16(int i)
    {
        throw new NotImplementedException();
    }

    public int GetInt32(int i)
    {
        throw new NotImplementedException();
    }

    public long GetInt64(int i)
    {
        throw new NotImplementedException();
    }

    public string GetName(int i)
    {
        throw new NotImplementedException();
    }

    public int GetOrdinal(string name)
    {
        throw new NotImplementedException();
    }

    public string GetString(int i)
    {
        throw new NotImplementedException();
    }

    public int GetValues(object[] values)
    {
        throw new NotImplementedException();
    }

    public bool IsDBNull(int i)
    {
        throw new NotImplementedException();
    }

    public object this[int i] => throw new NotImplementedException();

    public object this[string name] => throw new NotImplementedException();


    public void Close()
    {
        throw new NotImplementedException();
    }

    public DataTable? GetSchemaTable()
    {
        throw new NotImplementedException();
    }

    public bool NextResult()
    {
        throw new NotImplementedException();
    }

    public int Depth { get; }
    public bool IsClosed { get; }
    public int RecordsAffected { get; }
}

Full example download from here

Details: Written by: Stanko Milosev; Category: C#; Published: 08 February 2025; Last Updated: 08 February 2025; Hits: 565

Hier is one my example of Producer-Consumer Pattern.

First I want to read all files from HDD and put them in the queue (producer):

private void SearchForAllFilesAndPutThemInQueue(BlockingCollection<string> fileQueue, string path)
{
	foreach (string file in Directory.EnumerateFiles(path, "*.*", SearchOption.AllDirectories))
	{
		fileQueue.Add(file);
	}
}

Then I will read file names from queue and do something with (consumer):

private void ReadFileNamesFromQueue
(
	BlockingCollection<string>? fileQueue
	, BlockingCollection<(LatLngModel, string)>? gpsInfoQueue
)
{
	int i = 0;

	if (fileQueue is null) throw new ArgumentNullException(nameof(fileQueue));
	if (gpsInfoQueue is null) throw new ArgumentNullException(nameof(gpsInfoQueue));

	foreach (string file in fileQueue.GetConsumingEnumerable())
	{
		try
		{
			ExtractGpsInfoFromImageCommand extractGpsInfoFromImageCommand = new ExtractGpsInfoFromImageCommand();
			extractGpsInfoFromImageCommand.ImageFileNameToReadGpsFrom = file;
			extractGpsInfoFromImage.Execute(extractGpsInfoFromImageCommand);

			if (extractGpsInfoFromImageCommand.LatLngModel is not null)
			{
				gpsInfoQueue.Add((extractGpsInfoFromImageCommand.LatLngModel, file));
			}
		}
		catch (Exception ex)
		{
			Debug.WriteLine(ex.Message());
		}
	}
}

Here you can download my example, little bit complicated, where I get list of file in one queue, in second I try to extract GPS info, and from third queue I am saving to CSV file file name and longitude / latitude.

Details: Written by: Stanko Milosev; Category: C#; Published: 02 February 2025; Last Updated: 12 March 2025; Hits: 570

Here is my example of reading records from Database using Tasks in background, and Threads.

As Jon Skeet wrote on Stack Overflow:

A task returned by Task.Run() really is saying "I want you to execute this code separately"; the exact thread on which that code executes depends on a number of factors.

So, here is first my method with async. First install Microsoft.Data.SqlClient here notice that old System.Data.SqlClient is deprecated.

Now the method:

return Task.Run(() => ThreadReadFromDatabaseAsync(connectionString, sql));

private async Task ThreadReadFromDatabaseAsync(string connectionString, string sql)
{
	DateTime start = DateTime.Now;
	try
	{
		await using SqlConnection connection = new SqlConnection(connectionString);
		await connection.OpenAsync();
		await using SqlCommand command = new SqlCommand(sql, connection);
		command.CommandTimeout = 3600;
		await using SqlDataReader reader = await command.ExecuteReaderAsync();
		int recdCnt = 0;
		while (reader.Read())
		{
			UpdateUi.Execute($"{start} Reading using tasks record {recdCnt++}", LblRecordCount, Form);

			object[] values = new object[reader.FieldCount];
			reader.GetValues(values);
		}
	}
	catch (Exception ex)
	{
		UpdateUi.Execute($"Error in task execution: {ex.Message}", LblError, Form);
	}
	finally
	{
		UpdateUi.Execute($"{DateTime.Now} Done with task execution", LblStatus, Form);
	}
}

Here notice line:

while (reader.Read())

That I am not using ReadAsync. The problem is that at ReadAsync will stuck on reading from DB after few hundert records, this looks like bug described here.

Now another example with thread:

var thread = new Thread(() => ThreadReadFromDatabase(connectionString, sql))
{
	Name = "ThreadReadFromDatabase",
	IsBackground = true
};
thread.Start();

private void ThreadReadFromDatabase(string connectionString, string sql)
{
	DateTime start = DateTime.Now;

	try
	{
		using SqlConnection connection = new SqlConnection(connectionString);
		connection.Open();
		using SqlCommand command = new SqlCommand(sql, connection);
		command.CommandTimeout = 3600;
		using SqlDataReader reader = command.ExecuteReader();
		int recdCnt = 0;
		while (reader.Read())
		{
			UpdateUi.Execute($"{start} Reading using threads record {recdCnt++}", LblRecordCount, Form);

			object[] values = new object[reader.FieldCount];
			reader.GetValues(values);
		}
	}
	catch (Exception ex)
	{
		UpdateUi.Execute($"Error in thread execution: {ex.Message}", LblError, Form);
	}
	finally
	{
		UpdateUi.Execute($"{DateTime.Now} Done with thread execution", LblStatus, Form);
	}
}

Full example download from here

UPDATE 2025-03-12: Avoid using Task.Run for long-running work that blocks the thread

Also from the book Concurrency in C# Cookbook by Stephen Cleary:

As soon as you type new Thread(), it’s over; your project already has legacy code

Also check this Stack Overflow answer.

Update UI from Parallel.ForEach

Copy CSV file to MS SQL with SqlBulkCopy and IDataReader

Producer-Consumer Pattern

Tasks.Run vs Thread

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