一：背景
1. 讲故事
要想获取此类信息，看 dump 肯定是没有用的，只能给程序安装一个摄像头，在 Windows 平台上可以在 perfview 上配一个 Microsoft-Windows-DotNETRuntime:ContentionKeyword 事件轻松搞定，截图如下：
二：探究 dotnet-trace
1. 如何监控 lock 竞争
dotnet-trace是 CLR 团队写的一个跨平台的小工具，专门用于获取 .NET 程序的各种事件，可以理解成 PerfView 的一个子集，这里安装就不说了，详见官方文档：https://learn.microsoft.com/en-us/dotnet/core/diagnostics/dotnet-trace--clrevents 中配
contention事件即可，详情参见文档：https://learn.microsoft.com/en-us/dotnet/fundamentals/diagnostics/runtime-contention-events2. 测试案例
锁护送 现象，参考代码如下：
internal class Program { public static object lockMe = new object(; static void Main(string[] args { long i = 10; Parallel.For(0, int.MaxValue, new ParallelOptions( { MaxDegreeOfParallelism = 4 }, (j => { lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; lock (lockMe i++; }; } }将程序跑起来后，使用
dotnet-trace ps找到 PID，再用dotnet-trace进行跟踪，这里持续跟踪 1分钟。[root@localhost ~]# dotnet-trace ps 3316 dotnet /usr/share/dotnet/dotnet dotnet ConsoleApp3.dll [root@localhost ~]# dotnet-trace collect -p 3316 --clrevents contention --duration 00:00:01:00 Provider Name Keywords Level Enabled By Microsoft-Windows-DotNETRuntime 0x0000000000004000 Informational(4 --clrevents Process : /usr/share/dotnet/dotnet Output File : /root/dotnet_20230509_105906.nettrace Trace Duration : 00:00:01:00 [00:00:01:00] Recording trace 29.7885 (MB Press <Enter> or <Ctrl+C> to exit...148 (MB Stopping the trace. This may take several minutes depending on the application being traced. Trace completed. [root@localhost ~]# ls anaconda-ks.cfg dotnet_20230509_105906.nettrace Music Templates Desktop Downloads Pictures Videos Documents initial-setup-ks.cfg Public3. nettrace 文件分析
至于分析
dotnet_20230509_105906.nettrace的工具就特别多了，dotnet-trace，perf，perfview，visualstudio，不过我个人建议还是使用prefview，因为它的洞察能力会更好，用 perfview 打开之后点击EventStats观察统计信息：200w 的 start 和 stop 事件。
Events 面板中的
Microsoft-Windows-DotNETRuntime/Contention/Start事件，可以看到记录中每一次争抢的开始时间。4232 号线程就得到了两次连续执行。
HasStack="True" ThreadID="3,316" ProcessorNumber="0" ContentionFlags="Managed" ClrInstanceID="0" 中的
HasStack="True"就是告诉当前是有调用栈信息的，在Time MSec列点击右键选择Open Any Stacks。Main 方法中的
Parallel.For诱发的，非常清楚。三：总结
EventPipe 之上，特点就是跨平台，除了对锁竞争外，还有其他的各种有趣的事件，有兴趣的朋友可以查阅查阅。