A Unity3D coroutine wrapper for simple thread jobs. This can be added to any utility class, and then passed a thread function (run on the worker thread, be sure to make any shared variable access threadsafe) and a callback called when the thread is done (run on the main thread, no locking needed).

CoroutineWrapper.cs

    /// <summary>
    /// A coroutine used to run a function on once-off thread
    /// Note that the thread function is responsible for ending itself,
    /// the coroutine makes no effort to explicitly end the thread.
    /// </summary>
    /// <typeparam name="T">Type of the parameter passed to the thread function</typeparam>
    /// <param name="threadFunc">The thread function</param>
    /// <param name="doneFunc">Function called when the thread has completed it's work and is no longer alive.</param>
    /// <param name="param">Parameter passed to the thread function</param>
    /// <returns>An enumerator</returns>
    public static IEnumerator ThreadFuncCoroutine<T>(
        Action<T> threadFunc, 
        Action<T> doneFunc,
        T param) where T : class
    {
        // Queue the threadfunc on the thread pool
        // (wrap the user function in one that casts and we can check completion of)
        bool threadBusy = true;
        ThreadPool.QueueUserWorkItem(
            (object obj) =>
            {
                threadFunc(param as T);
                threadBusy = false;
            },
            param);

        // Wait for the thread to complete 
        do
        {
            // As long as the thread is still running, nothing to do
            yield return null;
        } while (threadBusy);
        
        // Notify that the thread is done
        if (null != doneFunc) doneFunc(param);
    }