问题记录Delegate to an instance method cannot have null 'this'

最近在写Socket服务器程序，写了一个简易的消息队列用于数据入库，遇到了这样的问题“Delegate to an instance method cannot have null 'this'”。

代码如下：

using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using AmtServer.Common;
using System.Linq;

namespace AmtServer.DAL
{
    public class DBJobProcessor
    {
        public readonly static DBJobProcessor Instance = new DBJobProcessor();
        //任务列表
        private List<JobArgs> j_list = new List<JobArgs>();
        private bool isdoingwork = false;
        private Thread jobthrd = new Thread(new ThreadStart(Instance.DoWork));
        private DBJobProcessor()
        {
            try
            {
                Start();
            }
            catch (Exception ex)
            {
                LogHelper.Logger.Error(ex);
            }
        }
        /// <summary>
        /// 开启线程
        /// </summary>
        public void Start()
        {
            jobthrd.IsBackground = true;
            jobthrd.Start();
        }
        /// <summary>
        /// 停止线程
        /// </summary>
        public void Stop()
        {
            try
            {
                jobthrd.Abort();
            }
            catch (System.Exception ex)
            {
                LogHelper.Logger.Error(ex);
            }
        }

        private void DoWork()
        {
            try
            {
                while (true)
                {
                    if (j_list.Count > 0)
                    {
                        if (!isdoingwork)
                        {
                            List<JobArgs> templst;
                            lock (((ICollection)j_list).SyncRoot)
                            {
                                int n = 0;
                                if (j_list.Count > 200)
                                {
                                    n = 200;
                                }
                                else
                                {
                                    n = j_list.Count;
                                }
                                JobArgs[] temp = new JobArgs[n];
                                j_list.CopyTo(0, temp, 0, n);
                                templst = new List<JobArgs>(temp);
                                j_list.RemoveRange(0, n);
                            }
                            DoWriteDB(templst.ToArray());
                        }
                    }
                    else
                    {
                        Thread.Sleep(10000);
                    }
                }
            }
            catch (Exception ex)
            {
                LogHelper.Logger.Error(ex);
            }
        }
        //执行数据库操作
        private void DoWriteDB(JobArgs[] ls)
        {
            try
            {
                isdoingwork = true;
                int result = 0;
                result += DapDBHelper.Execute(Constant.SQL_Position_Upsert, DapDBHelper.constr, ls);
                LogHelper.Instance.ShowInfoLog($"插入{result}/{ls.Length}条");
            }
            catch (Exception ex)
            {
                LogHelper.Logger.Error(ex);
                LogHelper.Instance.ShowInfoLog("DoWriteDB_Error:"+ex.Message);
            }
            finally
            {
                isdoingwork = false;
            }
        }
        /// <summary>
        /// 添加任务
        /// </summary>
        /// <param name="job"></param>
        public void AddJob(JobArgs job)
        {
            try
            {
                lock (((ICollection)j_list).SyncRoot)
                {
                    j_list.Add(job);
                }
            }
            catch (Exception ex)
            {
                LogHelper.Logger.Error(ex);
            }
        }

    }
}

问题出现在16行，Instance实例的线程订阅了Instance的方法，自己订阅自己。

很惭愧到现在还出现这种低级问题，还是得看书，基础不能拉下啊。。