Birleştirme

ProcessWithThreads ekle. Main'de LogProcessor.ProcessWithThreads(logs);
Örnek çözüm:
using System;
using System.Linq;

static class LogProcessor
{
    public static int ParseLevel(string level)
    {
        return level switch
        {
            "INFO" => 0,
            "WARN" => 1,
            "ERROR" => 2,
            _ => -1
        };
    }

    public static int CountByLevel(string[] logs, int targetLevel)
    {
        int count = 0;
        foreach (var log in logs)
        {
            if (ParseLevel(log.Split(':')[0]) == targetLevel)
            {
                count++;
            }
        }
        return count;
    }

    public static string ParseWithSpan(ReadOnlySpan<char> log)
    {
        int colon = log.IndexOf(':');
        if (colon < 0) return "";
        return log.Slice(0, colon).ToString();
    }

    public static unsafe int UnsafeSum(int a, int b)
    {
        int* pa = &a;
        int* pb = &b;
        return *pa + *pb;
    }

    public static async System.Threading.Tasks.Task Run(string[] logs)
    {
        var channel = System.Threading.Channels.Channel.CreateUnbounded<string>();
        var counts = new System.Collections.Concurrent.ConcurrentDictionary<string, int>();
        foreach (var log in logs)
        {
            await channel.Writer.WriteAsync(log);
        }
        channel.Writer.Complete();
        await foreach (var log in channel.Reader.ReadAllAsync())
        {
            var level = ParseWithSpan(log.AsSpan());
            counts.AddOrUpdate(level, 1, (_, n) => n + 1);
        }
        foreach (var kvp in counts.OrderBy(k => k.Key))
        {
            Console.WriteLine($"{kvp.Key}: {kvp.Value}");
        }
        LogProcessor.ProcessWithThreads(logs);
    }
}

static class DtoGenerator
{
    public static System.Collections.Generic.List<(string Hint, string Source)> Sources { get; } = new();

    public static void AddSource(string hintName, string source)
    {
        Sources.Add((hintName, source));
    }

    public static void Generate(string[] typeNames)
    {
        foreach (var name in typeNames)
        {
            AddSource(name + ".g.cs", $"public class {name}Dto {{ }}");
        }
    }

    private static int processed;

    public static void ProcessWithThreads(string[] logs)
    {
        processed = 0;
        System.Threading.Tasks.Parallel.ForEach(logs, _ =>
        {
            System.Threading.Interlocked.Increment(ref processed);
        });
        Console.WriteLine($"işlenen: {processed}");
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine("LogProcessor iskeleti hazır");
        var logs = new[] { "INFO: a", "WARN: b", "INFO: c", "ERROR: d" };
        Console.WriteLine(LogProcessor.CountByLevel(logs, 0));
        Console.WriteLine(LogProcessor.ParseWithSpan("ERROR: disk".AsSpan()));
        Console.WriteLine(LogProcessor.UnsafeSum(3, 4));
        LogProcessor.Run(logs).Wait();
        DtoGenerator.Generate(new[] { "Info", "Warn", "Error" });
        foreach (var entry in DtoGenerator.Sources)
        {
            Console.WriteLine(entry.Hint);
        }
    }
}