可以使用 System.Diagnostics.StackTrace 获取堆栈跟踪,但必须暂停线程。Suspend 和 Resume 功能已过时,因此我希望存在更好的方法。
6 回答
注意:跳到此答案的底部以获取更新。
到目前为止,这对我有用:
StackTrace GetStackTrace (Thread targetThread)
{
StackTrace stackTrace = null;
var ready = new ManualResetEventSlim();
new Thread (() =>
{
// Backstop to release thread in case of deadlock:
ready.Set();
Thread.Sleep (200);
try { targetThread.Resume(); } catch { }
}).Start();
ready.Wait();
targetThread.Suspend();
try { stackTrace = new StackTrace (targetThread, true); }
catch { /* Deadlock */ }
finally
{
try { targetThread.Resume(); }
catch { stackTrace = null; /* Deadlock */ }
}
return stackTrace;
}
如果它死锁,死锁会自动释放,你会得到一个空跟踪。(然后您可以再次调用它。)
我应该补充一点,经过几天的测试,我只能在我的 Core i7 机器上创建一个死锁。但是,当 CPU 以 100% 运行时,死锁在单核 VM 上很常见。
更新:此方法仅适用于 .NET Framework。在 .NET Core 和 .NET 5+ 中,Suspend
并且Resume
无法调用,因此您必须使用替代方法,例如 Microsoft 的 ClrMD 库。添加对 Microsoft.Diagnostics.Runtime 包的 NuGet 引用;然后您可以调用DataTarget.AttachToProcess
以获取有关线程和堆栈的信息。请注意,您不能对自己的流程进行抽样,因此您必须启动另一个流程,但这并不困难。这是一个基本的控制台演示,说明了该过程,使用重定向的标准输出将堆栈跟踪发送回主机:
using Microsoft.Diagnostics.Runtime;
using System.Diagnostics;
using System.Reflection;
if (args.Length == 3 &&
int.TryParse (args [0], out int pid) &&
int.TryParse (args [1], out int threadID) &&
int.TryParse (args [2], out int sampleInterval))
{
// We're being called from the Process.Start call below.
ThreadSampler.Start (pid, threadID, sampleInterval);
}
else
{
// Start ThreadSampler in another process, with 100ms sampling interval
var startInfo = new ProcessStartInfo (
Path.ChangeExtension (Assembly.GetExecutingAssembly().Location, ".exe"),
Process.GetCurrentProcess().Id + " " + Thread.CurrentThread.ManagedThreadId + " 100")
{
RedirectStandardOutput = true,
CreateNoWindow = true
};
var proc = Process.Start (startInfo);
proc.OutputDataReceived += (sender, args) =>
Console.WriteLine (args.Data != "" ? " " + args.Data : "New stack trace:");
proc.BeginOutputReadLine();
// Do some work to test the stack trace sampling
Demo.DemoStackTrace();
// Kill the worker process when we're done.
proc.Kill();
}
class Demo
{
public static void DemoStackTrace()
{
for (int i = 0; i < 10; i++)
{
Method1();
Method2();
Method3();
}
}
static void Method1()
{
Foo();
}
static void Method2()
{
Foo();
}
static void Method3()
{
Foo();
}
static void Foo() => Thread.Sleep (100);
}
static class ThreadSampler
{
public static void Start (int pid, int threadID, int sampleInterval)
{
DataTarget target = DataTarget.AttachToProcess (pid, false);
ClrRuntime runtime = target.ClrVersions [0].CreateRuntime();
while (true)
{
// Flush cached data, otherwise we'll get old execution info.
runtime.FlushCachedData();
foreach (ClrThread thread in runtime.Threads)
if (thread.ManagedThreadId == threadID)
{
Console.WriteLine(); // Signal new stack trace
foreach (var frame in thread.EnumerateStackTrace().Take (100))
if (frame.Kind == ClrStackFrameKind.ManagedMethod)
Console.WriteLine (" " + frame.ToString());
break;
}
Thread.Sleep (sampleInterval);
}
}
}
这是 LINQPad 6+ 用来在查询中显示实时执行跟踪的机制(带有额外的检查、元数据探测和更精细的 IPC)。
这是一个旧线程,但只是想警告建议的解决方案:暂停和恢复解决方案不起作用 - 我刚刚在尝试序列暂停/堆栈跟踪/恢复的代码中遇到了死锁。
问题是 StackTrace 构造函数执行 RuntimeMethodHandle -> MethodBase 转换,这改变了内部 MethodInfoCache,它需要一个锁。发生死锁是因为我正在检查的线程也在进行反射,并且持有该锁。
遗憾的是,挂起/恢复的东西没有在 StackTrace 构造函数中完成——那么这个问题很容易被规避。
根据C# 3.0 in a Nutshell,这是可以调用 Suspend/Resume 的少数情况之一。
正如我在评论中提到的,上面提出的解决方案仍然存在很小的死锁概率。请在下面找到我的版本。
private static StackTrace GetStackTrace(Thread targetThread) {
using (ManualResetEvent fallbackThreadReady = new ManualResetEvent(false), exitedSafely = new ManualResetEvent(false)) {
Thread fallbackThread = new Thread(delegate() {
fallbackThreadReady.Set();
while (!exitedSafely.WaitOne(200)) {
try {
targetThread.Resume();
} catch (Exception) {/*Whatever happens, do never stop to resume the target-thread regularly until the main-thread has exited safely.*/}
}
});
fallbackThread.Name = "GetStackFallbackThread";
try {
fallbackThread.Start();
fallbackThreadReady.WaitOne();
//From here, you have about 200ms to get the stack-trace.
targetThread.Suspend();
StackTrace trace = null;
try {
trace = new StackTrace(targetThread, true);
} catch (ThreadStateException) {
//failed to get stack trace, since the fallback-thread resumed the thread
//possible reasons:
//1.) This thread was just too slow (not very likely)
//2.) The deadlock ocurred and the fallbackThread rescued the situation.
//In both cases just return null.
}
try {
targetThread.Resume();
} catch (ThreadStateException) {/*Thread is running again already*/}
return trace;
} finally {
//Just signal the backup-thread to stop.
exitedSafely.Set();
//Join the thread to avoid disposing "exited safely" too early. And also make sure that no leftover threads are cluttering iis by accident.
fallbackThread.Join();
}
}
}
我认为,ManualResetEventSlim“fallbackThreadReady”并不是真正必要的,但为什么要在这种微妙的情况下冒险呢?
看起来这是过去受支持的操作,但不幸的是,微软已经过时了:https ://msdn.microsoft.com/en-us/library/t2k35tat(v=vs.110).aspx
我认为,如果您想在没有目标线程的合作的情况下执行此操作(例如,在您的线程执行堆栈跟踪时,让它调用一个在信号量上阻塞它的方法或其他东西),您将需要使用已弃用的 API。
一种可能的替代方法是使用.NET 调试器使用的基于 COM 的 ICorDebug接口。MDbg 代码库可能会给你一个开始: