As shown in the previous post, the processing of ProcessInfo diagnostic commands is easy because you send a request and read the different fields from the response. This is different if you want to receive events from the CLR via EventPipe. …

The previous post was describing the C# helpers to communicate with the diagnostic server in the CLR of a running .NET application. If, like me, you must write native code (i.e not in C#), you will need to implement the transport and protocol yourself. And, as you will see, it…

Introduction As I explained during a DotNext conference session, the .NET CLI tools such as dotnet-trace, dotnet-counter or dotnet-dump are communicating with the CLR thanks to Named Pipe on Windows and Domain Socket on Linux. Within the CLR, a diagnostic server thread is responsible for answering requests. A communication protocol allows…

Introduction With the new 2.10 release of the Datadog .NET Tracer and Continuous Profiler available, it is time to update some investigation workflows I already introduced. New features have been added to help you diagnose performance issues in your .NET applications: Linux support! Code Hotspots: allow you to automatically navigate from…

Here comes the end of the series about .NET profiling APIs. This final episode describes how to get fields of a value type instance and how to deal with exceptions. Getting fields of a value type instance The case of a value type is very similar to a reference type except that the address you receive points…

Introduction The beta of Datadog .NET Continuous Profiler is available! This is a great opportunity to show how to use the different tools provided by Datadog to troubleshoot .NET applications facing performance issues. Tess Ferrandez updated her famous BuggyBits application to .NET Core. Among the different available scenarios, let’s see how…

Introduction After getting basic and strings parameters, it is time to look at arrays and reference types. Accessing managed arrays You check against null array parameter the same way as for string: The ELEMENT_TYPE_SZARRAY applies to single dimension arrays including jagged arrays. ELEMENT_TYPE_ARRAY is used for matrice : Since arrays are reference…

Introduction From the list of arguments with their type, it becomes possible to figure out their value when a method gets called. The rest of this post describes how to access method call parameters and get the value of numbers and strings. Where are my parameters? When you pass COR_PRF_ENABLE_FUNCTION_ARGS to ICorProfilerInfo::SetEventMask, the runtime prepares…

Introduction After introducing the CLR profiling API by tracing managed methods calls, then dealing with assemblies and types, it is time to look at methods signatures. Remember that the starting point is the FunctionID received by the Enter callback each time a method is executed. The question answered by this post…