下的程序調(diào)試相對C/C++要簡單很多，少了那些令人頭疼的指針越界的問題。不過當(dāng)你的程序遇到如下問題時(shí)，依然非常棘手：
進(jìn)程異常終止。解決方案見 .Net 下未捕獲異常的處理
內(nèi)存泄漏或者內(nèi)存申請后程序始終沒有釋放。解決方案見 用 .NET Memory Profiler 跟蹤.net 應(yīng)用內(nèi)存使用情況--基本應(yīng)用篇 。如果通過自己編寫的程序監(jiān)控，我將在以后的文章中闡述。
線程因未知原因掛起，比如死鎖。
程序死循環(huán)。
本文將闡述如果編寫程序?qū)髢烧吖收蠈?shí)時(shí)跟蹤并報(bào)告。
首先我們需要一個(gè)單獨(dú)的監(jiān)控線程來監(jiān)控需要監(jiān)控的線程
我做了一個(gè)監(jiān)控類 ThreadMonitor，在開始監(jiān)控之前，我們將監(jiān)控線程的優(yōu)先級設(shè)置為最高。
public ThreadMonitor()
{
_MonitorThread = new Thread(new ThreadStart(MonitorTask));
_MonitorThread.Priority = ThreadPriority.Highest;
_MonitorThread.IsBackground = true;
} |
接下來我們?yōu)檫@個(gè)線程提供幾個(gè)公共方法
方法讓調(diào)用者啟動監(jiān)控
方法用于將需要監(jiān)控的線程注冊到監(jiān)控列表中
方法后面說明
/**////
/// Start monitor
///
public void Start()
{
_MonitorThread.Start();
}
/**////
/// Monitor register
///
/// Monitor parameter
public void Register(MonitorParameter monitorPara)
{
Debug.Assert(monitorPara != null);
Debug.Assert(monitorPara.Thread != null);
if (GetTCB(monitorPara.Thread) != null)
{
throw new System.ArgumentException("Register repeatedly!");
}
lock (_RegisterLock)
{
_TCBTable.Add(monitorPara.Thread.ManagedThreadId, new TCB(monitorPara));
}
}
public void Heartbeat(Thread t)
{
TCB tcb = GetTCB(t);
if (tcb == null)
{
throw new System.ArgumentException("This thread was not registered!");
}
tcb.LastHeartbeat = DateTime.Now;
tcb.HitTimes = 0;
tcb.Status &= ~ThreadStatus.Hang;
} |
下面讓我來說說如何監(jiān)控某個(gè)線程掛起。
監(jiān)控線程提供了一個(gè)心跳調(diào)用 Heartbeat ，被監(jiān)控的線程必須設(shè)置一個(gè)定時(shí)器定時(shí)向監(jiān)控線程發(fā)送心跳，如果監(jiān)控線程在一定時(shí)間內(nèi)無法收到這個(gè)心跳消息，則認(rèn)為被監(jiān)控線程非正常掛起了。這個(gè)時(shí)間又MonitorParameter參數(shù)的HangTimeout指定。
光監(jiān)控到線程掛起還不夠，我們必須要報(bào)告線程當(dāng)前掛起的位置才有實(shí)際意義。那么如何獲得線程當(dāng)前的調(diào)用位置呢?.Net framework 為我們提供了獲取線程當(dāng)前堆棧調(diào)用回溯的方法。見下面代碼
private string GetThreadStackTrace(Thread t)
{
bool needFileInfo = NeedFileInfo;
t.Suspend();
StackTrace stack = new StackTrace(t, needFileInfo);
t.Resume();
return stack.ToString();
} |
這里需要說明的是StackTrace(t, needFileInfo) 必須在線程t Suspend后 才能調(diào)用，否則會發(fā)生異常。但Thread.Suspend 調(diào)用是比較危險(xiǎn)的，因?yàn)檎{(diào)用者無法知道線程t掛起前的運(yùn)行狀況，可能線程t目前正在等待某個(gè)資源，這時(shí)強(qiáng)制掛起，非常容易造成程序死鎖。不過值得慶幸的是StackTrace(t, needFileInfo)的調(diào)用不會和其他線程尤其是調(diào)用線程產(chǎn)生資源沖突，但我們必須在這一句執(zhí)行結(jié)束后迅速調(diào)用 t.Resume 結(jié)束線程t的掛起狀態(tài)。
談完了對線程非正常掛起的監(jiān)控，再談?wù)剬Τ绦蛩姥h(huán)的監(jiān)控。
在決定采用我現(xiàn)在的這個(gè)方案之前，我曾經(jīng)想通過 GetThreadTimes 這個(gè)API 函數(shù)得到被監(jiān)控線程的實(shí)際CPU運(yùn)行時(shí)間，通過這個(gè)時(shí)間來計(jì)算其CPU占有率，但很遺憾，我的嘗試失敗了。通過非當(dāng)前線程下調(diào)用 GetThreadTimes 無法得到對應(yīng)線程的CPU時(shí)間。(好像非托管線程可以，但.Net的托管線程我試了，確實(shí)不行，但原因我還沒弄明白)另外GetThreadTimes 統(tǒng)計(jì)不夠準(zhǔn)確 見 對老趙寫的簡單性能計(jì)數(shù)器的修改續(xù)- 關(guān)于
所以沒有辦法，我采用了一個(gè)不是很理想的方案
定時(shí)統(tǒng)計(jì)當(dāng)前進(jìn)程的TotalProcessorTime 來計(jì)算當(dāng)前線程的CPU占有率，如果這個(gè)CPU占有率在一段時(shí)間內(nèi)大于 100 / (CPU 數(shù))* 90% ，則認(rèn)為當(dāng)前進(jìn)程出現(xiàn)了死循環(huán)。這個(gè)測試時(shí)間由 MonitorParameter參數(shù)的DeadCycleTimeout 屬性指定。
這就出現(xiàn)了一個(gè)問題，我們只知道程序死循環(huán)了，但不知道具體是那個(gè)線程死循環(huán)，那么如何找到真正死循環(huán)的線程呢?
我采用的方法是每秒鐘檢測一次線程當(dāng)前狀態(tài)，如果當(dāng)前狀態(tài)為運(yùn)行狀態(tài)則表示命中一次，在確認(rèn)出現(xiàn)死循環(huán)后我們在來檢查在一個(gè)檢查周期內(nèi)的命中次數(shù)，如果這個(gè)命中次數(shù)足夠高，則認(rèn)為是該線程死循環(huán)了。不過這樣還是有問題，主線程在等待windows 消息時(shí) 或者控制臺程序線程在等待控制臺輸入時(shí)，該線程的狀態(tài)居然始終是 Runing ，其實(shí)是阻塞了，但我沒有找到一個(gè)很好的方法來得到線程當(dāng)前處于阻塞狀態(tài)。怎么辦?我想了個(gè)笨辦法，就是在上面兩個(gè)條件都符合的情況下再看看在此期間有沒有心跳，如果沒有心跳，說明死循環(huán)了。但如果有心跳也不一定就沒有死循環(huán)，遇到這種情況，就將可疑的都全部報(bào)告了，靠人來判斷吧。
我寫了一個(gè)示例代碼，代碼中有一個(gè)Winform 主線程 和 一個(gè)計(jì)數(shù)器線程，計(jì)數(shù)器線程每秒記一次數(shù)，并更新界面。監(jiān)控線程檢查到非正常掛起或者死循環(huán)，將在當(dāng)前目錄下寫一個(gè)Report.log 輸出監(jiān)控報(bào)告。
點(diǎn)擊Hang后主線程休眠20秒，計(jì)數(shù)器線程由于要更新界面，也同樣會被掛起。
監(jiān)控線程檢查到兩個(gè)線程掛起后報(bào)告如下：
ThreadMonitorEvent
Thread Name:Main thread
Thread Status:Hang
Thread Stack: at System.Threading.Thread.SleepInternal(Int32 millisecondsTimeout)
at System.Threading.Thread.Sleep(Int32 millisecondsTimeout)
at DotNetDebug.Form1.buttonHang_Click(Object sender, EventArgs e)
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at DotNetDebug.Program.Main()
at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
2:38:40 PM
ThreadMonitorEvent
Thread Name:Counter thread
Thread Status:Hang
Thread Stack: at System.Threading.WaitHandle.WaitOneNative(SafeWaitHandle waitHandle, UInt32 millisecondsTimeout, Boolean hasThreadAffinity, Boolean exitContext)
at System.Threading.WaitHandle.WaitOne(Int64 timeout, Boolean exitContext)
at System.Threading.WaitHandle.WaitOne(Int32 millisecondsTimeout, Boolean exitContext)
at System.Windows.Forms.Control.WaitForWaitHandle(WaitHandle waitHandle)
at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
at System.Windows.Forms.Control.Invoke(Delegate method)
at DotNetDebug.Form1.Counter()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart() |
點(diǎn)擊DeadCycle 按鈕后，讓計(jì)數(shù)器線程死循環(huán)，但主線程不死循環(huán)。
監(jiān)控線程檢查到計(jì)數(shù)器線程死循環(huán)后報(bào)告如下：
2:37:51 PM
ThreadMonitorEvent
Thread Name:Counter thread
Thread Status:Hang
Thread Stack: at DotNetDebug.Form1.DoDeadCycle()
at DotNetDebug.Form1.Counter()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
2:37:52 PM
ThreadMonitorEvent
Thread Name:Counter thread
Thread Status:Hang, DeadCycle
Thread Stack: at DotNetDebug.Form1.DoDeadCycle()
at DotNetDebug.Form1.Counter()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart() |
下面是示例代碼在
以下是測試代碼。完整源碼的下載位置: 完整源碼
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Threading;
using Sys.Diagnostics;
namespace DotNetDebug
{
public partial class Form1 : Form
{
Thread _CounterThread;
ThreadMonitor _ThreadMonitor = new ThreadMonitor();
bool _DeadCycle = false;
delegate void CounterDelegate();
private void DoDeadCycle()
{
while (_DeadCycle)
{
}
}
private void Counter()
{
int count = 0;
while (true)
{
DoDeadCycle();
labelCounter.Invoke(new CounterDelegate(delegate() { labelCounter.Text = (count++).ToString(); }));
_ThreadMonitor.Heartbeat(Thread.CurrentThread);
Thread.Sleep(1000);
}
}
public Form1()
{
InitializeComponent();
}
void OnThreadMonitorEvent(object sender, ThreadMonitor.ThreadMonitorEvent args)
{
StringBuilder sb = new StringBuilder();
sb.AppendLine(DateTime.Now.ToLongTimeString());
sb.AppendLine("ThreadMonitorEvent");
sb.AppendLine("Thread Name:" + args.Name);
sb.AppendLine("Thread Status:" + args.Status.ToString());
sb.AppendLine("Thread Stack:" + args.StackTrace);
using (System.IO.FileStream fs =
new System.IO.FileStream("report.log", System.IO.FileMode.Append,
System.IO.FileAccess.Write))
{
using (System.IO.StreamWriter sw = new System.IO.StreamWriter(fs))
{
sw.WriteLine(sb.ToString());
}
}
}
private void Form1_Load(object sender, EventArgs e)
{
_ThreadMonitor.ThradMonitorEventHandler +=
new EventHandler(OnThreadMonitorEvent);
_CounterThread = new Thread(new ThreadStart(Counter));
_CounterThread.IsBackground = true;
_ThreadMonitor.Register(new ThreadMonitor.MonitorParameter(
Thread.CurrentThread, "Main thread", 10000, 5000,
ThreadMonitor.MonitorFlag.MonitorHang |
ThreadMonitor.MonitorFlag.MonitorDeadCycle));
_ThreadMonitor.Register(new ThreadMonitor.MonitorParameter(
_CounterThread, "Counter thread",
ThreadMonitor.MonitorFlag.MonitorHang |
ThreadMonitor.MonitorFlag.MonitorDeadCycle));
_CounterThread.Start();
timerHeartbeat.Interval = 1000;
timerHeartbeat.Enabled = true;
_ThreadMonitor.Start();
}
private void timerHeartBeat_Tick(object sender, EventArgs e)
{
_ThreadMonitor.Heartbeat(Thread.CurrentThread);
}
private void ButtonDeadCycle_Click(object sender, EventArgs e)
{
_DeadCycle = true;
}
private void buttonHang_Click(object sender, EventArgs e)
{
Thread.Sleep(20000);
}
}
} |
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