c# - Getting list of currently active managed threads in .NET?

Question

For a "log information for support" type of function I'd like to enumerate and dump active thread information.

I'm well aware of the fact that race conditions can make this information semi-inaccurate, but I'd like to try to get the best possible result, even if it isn't 100% accurate.

I looked at Process.Threads, but it returns ProcessThread objects, I'd like to have a collection of Thread objects, so that I can log their name, and whether they're background threads or not.

Is there such a collection available, even if it is just a snapshot of the active threads when I call it?

ie.

Thread[] activeThreads = ??

Note, to be clear, I am not asking about Process.Threads, this collection gives me a lot, but not all of what I want. I want to know how much time specific named threads in our application is currently using (which means I will have to look at connecting the two types of objects later, but the names is more important than the CPU time to begin with.)

Answer 1

If you're willing to replace your application's Thread creations with another wrapper class, said wrapper class can track the active and inactive Threads for you. Here's a minimal workable shell of such a wrapper:

namespace ThreadTracker
{
    using System.Collections.Generic;
    using System.Collections.ObjectModel;
    using System.Threading;

    public class TrackedThread
    {
        private static readonly IList<Thread> threadList = new List<Thread>();

        private readonly Thread thread;

        private readonly ParameterizedThreadStart start1;

        private readonly ThreadStart start2;

        public TrackedThread(ParameterizedThreadStart start)
        {
            this.start1 = start;
            this.thread = new Thread(this.StartThreadParameterized);
            lock (threadList)
            {
                threadList.Add(this.thread);
            }
        }

        public TrackedThread(ThreadStart start)
        {
            this.start2 = start;
            this.thread = new Thread(this.StartThread);
            lock (threadList)
            {
                threadList.Add(this.thread);
            }
        }

        public TrackedThread(ParameterizedThreadStart start, int maxStackSize)
        {
            this.start1 = start;
            this.thread = new Thread(this.StartThreadParameterized, maxStackSize);
            lock (threadList)
            {
                threadList.Add(this.thread);
            }
        }

        public TrackedThread(ThreadStart start, int maxStackSize)
        {
            this.start2 = start;
            this.thread = new Thread(this.StartThread, maxStackSize);
            lock (threadList)
            {
                threadList.Add(this.thread);
            }
        }

        public static int Count
        {
            get
            {
                lock (threadList)
                {
                    return threadList.Count;
                }
            }
        }

        public static IEnumerable<Thread> ThreadList
        {
            get
            {
                lock (threadList)
                {
                    return new ReadOnlyCollection<Thread>(threadList);
                }
            }
        }

        // either: (a) expose the thread object itself via a property or,
        // (b) expose the other Thread public methods you need to replicate.
        // This example uses (a).
        public Thread Thread
        {
            get
            {
                return this.thread;
            }
        }

        private void StartThreadParameterized(object obj)
        {
            try
            {
                this.start1(obj);
            }
            finally
            {
                lock (threadList)
                {
                    threadList.Remove(this.thread);
                }
            }
        }

        private void StartThread()
        {
            try
            {
                this.start2();
            }
            finally
            {
                lock (threadList)
                {
                    threadList.Remove(this.thread);
                }
            }
        }
    }
}

and a quick test driver of it (note I do not iterate over the list of threads, merely get the count in the list):

namespace ThreadTracker
{
    using System;
    using System.Threading;

    internal static class Program
    {
        private static void Main()
        {
            var thread1 = new TrackedThread(DoNothingForFiveSeconds);
            var thread2 = new TrackedThread(DoNothingForTenSeconds);
            var thread3 = new TrackedThread(DoNothingForSomeTime);

            thread1.Thread.Start();
            thread2.Thread.Start();
            thread3.Thread.Start(15);
            while (TrackedThread.Count > 0)
            {
                Console.WriteLine(TrackedThread.Count);
            }

            Console.ReadLine();
        }

        private static void DoNothingForFiveSeconds()
        {
            Thread.Sleep(5000);
        }

        private static void DoNothingForTenSeconds()
        {
            Thread.Sleep(10000);
        }

        private static void DoNothingForSomeTime(object seconds)
        {
            Thread.Sleep(1000 * (int)seconds);
        }
    }
}

Not sure if you can go such a route, but it will accomplish the goal if you're able to incorporate at an early stage of development.